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Explore our services and get in touch Our Services 01. Custom Paleo Art Commission a unique piece of artwork depicting your favorite prehistoric creature or a scene from ancient life in the Midwest. Our artists specialize in scientifically accurate yet artistically compelling paleo art, perfect for collectors or educational displays. Get a personalized vision brought to life with detailed textures and vibrant portrayals of ancient worlds. This service is ideal for individuals seeking bespoke art for their collections or projects. Show more 02. Detailed Animal Study Go beyond the basics with our in-depth profiles on specific prehistoric animals from the Midwest region. Each package includes detailed biological information, habitat reconstruction, and a curated selection of related artwork. Understand the ancient ecosystems and the creatures that inhabited them with scientifically-grounded insights. Ideal for educators, enthusiasts, and researchers seeking comprehensive data. Show more 03. Paleo Art Print Own a piece of prehistoric wonder with high-quality prints of our featured paleo artwork. Available in various sizes, these prints are perfect for decorating home offices, educational spaces, or any enthusiast's collection. Each print captures the majesty and mystery of extinct life in vivid detail. Enhance your environment with stunning visuals from a bygone era. Show more

Discover different types of extinct saber-toothed cats, bears and canids found in the Midwest during the Pleistocene epoch, including animals like Smilodon and the dire wolf Carnivora Bears, Dogs, Cats and their Relatives Carnivora is a diverse order of mammals which includes all of today’s cats, dogs, bears, weasels, skunks, otters, raccoons, coatis, seals and sea lions, along with their closest relatives. The name carnivora refers to the meat eating diets common amongst the members of this group, but it should be noted that not all carnivorous animals are carnivorans and not all carnivorans are carnivorous. Although many carnivorans almost exclusively eat meat, some members of this group, like raccoons and grizzly bears, eat a mixed diet of meat and plant matter. Furthermore other carnivorans, like the olinguito and kinkajou, almost exclusively eat fruit. During the Pleistocene epoch the Midwest was home to several types of large carnivorans which have since disappeared. The most famous of these extinct carnivorans are without a doubt the large saber-toothed cats like Smilodon and Homotherium , but other animals like short-faced bears, American lions and giant jaguars were also found in this region at the time. Anatomy (BELOW) Features of the cranial and mandibular anatomy of a dire wolf. In many types of carnivorans a large set of teeth called the carnassial complex is positioned along the rear edges of the mouth in order to help with cutting through meat. Skeletal Anatomy Most terrestrial carnivorans are built to be cursorial animals who are very good runners. As a result, the bones of their limbs are usually fairly long which gives many carnivorans a long stride length. Aquatic and burrowing carnivorans tend to have shorter limbs and specialized hand and foot anatomies which help them to move through water or to claw through dirt. Many carnivorans are digitigrade, meaning that they walk on the bones of their tiptoes instead of walking with their heels against the ground. This type of locomotion is another hallmark of animals who are adapted for running. In contrast, some species, including bears, are plantigrade and place their entire foot on the ground while walking. The forelimbs of carnivorans are often more flexible than those of other types of mammals owing to the presence of a reduced or loosely attached clavicle which gives these animals a greater range of limb movement. Carnivorans also tend to have skeletal features which help them hunt down prey, although some vegetarian or insect-eating carnivorans do also exist. Their skulls are strongly built and tend to support very powerful jaw muscles. Their large canine teeth are used for grasping and restraining prey, while the specialized carnassial complexes along the sides of their mouths help to cut or shear through meat. (BELOW) A labeled diagram of the skeletal anatomy of a dire wolf, based on a skeletal mount of bones from the La Brea Tar Pits which is on display at the KU Natural History Museum. External Anatomy Over millions of years, carnivorans have evolved many soft tissue structures which help different groups of these mammals to function better in their preferred ecological niches. One particular feature found in most carnivorans is their forward-facing eyes which give them a greater degree of binocular vision and a far more accurate sense of depth perception. This trait is particularly helpful when it comes to hunting and navigating complex terrain or when climbing trees. Most of these animals also have rather large external ears with distinctive shapes which allow them to pick up on subtle sounds which fall outside of the human hearing range. Many carnivorans have long whiskers surrounding their snouts that serve as sensory organs that help detect nearby objects. The facial structures of carnivorans can vary greatly between different groups. Some species have long snouts and muzzles, while others, such as felids, have shorter and more rounded faces. The limbs of carnivorans are typically strong and muscular and are adapted for a wide range of behaviors including climbing, burrowing, and swimming. Most species have paws tipped with several digits and sharp claws. In some groups these claws are habitually held off the ground when retracted while in other carnivorans the nails tend to contact the ground at all times. Tail structure differs among different species but in groups with longer tails, these parts of their bodies work as tools for communication or for keeping balance while moving through trees or when running at high speeds. (BELOW) Features of the external anatomy of an American cheetah. Most carnivorans have whiskers, padded feet and flexible spines which absorb the physical stress created by bodies while running at high speeds. Bears (Ursidae) Short-faced bears By the end of the Pleistocene, North America was already home to the brown, black and polar bears we associate with the continent today, but a few other types of now extinct bears would have also made their home in this area at that time. These were the short-faced bears which are known from two main species found in Pleistocene deposits. The largest of these was the Giant short-faced bear Arctodus simu s, while a smaller species, Arctodus pristinus, lived in parts of Florida and the area which would one day become the southeastern US. Lesser short-faced bear Arctodus pristinus Temporal Range: 2.5 million years ago to approximately 500,000 years ago Geographic Range: Southern and eastern North America Species: A. simus, A pristinus Diet: Omnivorous, fish, meat, roots, invertebrates, carrion Arctodus pristinus was a smaller species of short-faced bear whose fossils are found in the southeastern US in deposits from the early Pleistocene. In the parts of its range which extended into Florida, it would have lived alongside yet another species of short-faced bear, Tremarctos floridanus , as well as saber-toothed cats like Xenosmilus and large canids. Although it was smaller than Arctodus simus, Arctodus pristinus would still have grown to larger sizes than many types of bears still found in North America today. Like all other short-faced tremarctine bears, Arctodus pristinus had a tall shoulder, long legs and a somewhat shortened snout. Arctodus pristinus is thought to have had an omnivorous diet, feeding on carrion, fruits, tubers, fish and possibly occasionally hunting for live prey. They may have used their large body sizes to frighten other carnivores away from their kill sites. This behavior involving opportunistically stealing food from other animals is sometimes seen in living grizzly bears in western North America so it is not unreasonable to think that short-faced bears may have engaged in similar behaviors. Giant short-faced bear Arctodus simus Temporal Range: 2 million years ago to approximately 12,800 years ago Geographic Range: Found across North America, Alaska to Mexico Species: A. simus, A pristinus Diet: Omnivorous, fish, meat, roots, invertebrates, carrion The giant short-faced bear, Arctodus simus , was the largest bear found in North America during the Pleistocene epoch. These animals would have been larger than today’s polar bears. They were well over five feet tall at the shoulder and would have easily stood over 10 feet tall standing on their hind legs. Arctodu s was part of a subfamily of bears called Tremarctinae, a group whose only living member is the spectacled bear found in parts of the Andes mountains in South America. The tremarctine subfamily first appears in the fossil record at the end of the Miocene epoch with remains of animals like Plionarctos found in parts of central North America. Many of the larger tremarctine bears like Arctodus simu s and the South American Arctotherium angustiden s appeared later on in the Pleistocene. Although it is often called the “short faced” bear, Arctodus ’s face was not as flattened as is seen in older paleoart. Although its snout was shorter than that of a living grizzly bear, Arctodus ’s nasal tissues would have extended the length of their noses further forward than the shape of the animal’s skull would initially suggest. (BELOW) The skull of a short-faced bear on display at the KU Natural History Museum. Although the muzzles of these animals were shorter than those of grizzlies or black bears, these extinct bears would still have had a distinct snout Cats (Felidae) Sabertooths and ancient felines Cats form a family of carnivorous mammals with short snouts who typically have retractable claws. All members of the cat family are hypercarnivorous, almost exclusively eating meat. The ancestors of cats crossed into North America from Eurasia sometime during the Miocene epoch and by the start of the Pleistocene, the Midwest was home to several types of large cats, many of which were endemic to the North American continent. The best known prehistoric cats from this time period are saber-toothed cats like Smilodon and Homotherium . Extinct relatives of the pantherine cats, like American lions and giant jaguars, could also be found in this region, living alongside relatives of today’s mountain lions who had independently developed long legs adapted for chasing down fast moving prey Scimitar-toothed cat Homotherium serum Temporal Range: 4 million years ago to approximately 12,000 years ago Geographic Range: Genus found in the Americas, Eurasia, Africa Species: H. serum, H. latidens, H, ischyrus, H. venezuelensis Diet: Carnivorous, large mammalian prey The scimitar-toothed cat, Homotherium, was one of the most widely distributed genera of saber- toothed cats. Its fossils have been found in Europe, Asia, Africa, North America and South America, a range comparable to the historic distribution of the genus Panthera. Like most of its relatives it had a short tail and longer limbs than many of today’s cats. Compared with animals like Smilodon, Homotherium had shorter saber teeth and a longer skull. Homotherium is special since it is not only known from fossils of its bones. A recently discovered mummy of a Homotherium latidens cub from Siberia tells us that this species had reddish-brown fur as cubs. This information may not carry over to the North American species of Homotherium, Homotherium serum , but it nevertheless gives us a surprisingly detailed insight into the appearances of at least some of these ancient cats. Homotherium ’s short sabers may not have been visible when these cats had their mouths closed in life. Like many of today’s cats, it’s likely that they kept their canine teeth sheathed inside of fleshy pockets lining the outside edges of their gum tissues of the lower jaw. American cheetah Miracinonyx inexpectatus, M. trumani Temporal Range: 2.5 million years ago to approximately 16,000 years ago Geographic Range: Genus is found across North America Species: M. inexpectatus, M. trumani Diet: Carnivorous, large mammalian prey Despite its name, the American cheetah, Miracinonyx , was not a close relative of today’s cheetahs. These long-legged cats were instead distant relatives of today’s mountain lions. Two species of Miracinonyx are currently recognized; Miracinonyx inexpectatus and Miracinonyx trumani. Miracinonyx trumani is the most cheetah-like of the two species, with a narrow body and longer legs than most cats. The purpose of these long legs is unclear, with some studies suggesting that they would have filled a similar ecological role to the living cheetah, using bursts of speed to chase down pronghorns or deer. Other studies point out that these animals did not have the same foot structure seen in living cheetahs, possibly indicating that these animals were not as well suited to running down prey as we may have once thought. Miracinonyx inexpectatus had a body shape much more similar to that of today’s mountain lions. These animals may have been the ancestors of Miracinonyx trumani. American lion Panthera atrox Temporal Range: 129,000 years ago to approximately 13,000 years ago Geographic Range: North America as far south as Guatemala Species: P. atrox Diet: Carnivorous, large mammalian prey One of the largest cats found in Pleistocene North America was not a saber-toothed cat at all, but rather a member of the same genus as today’s leopards, tigers and lions. This was the American Lion, Panthera atrox , possibly one of the largest cats ever to exist. These giants were around 25-30% larger than today’s lions, standing nearly four feet tall at the shoulder. American lions are thought to have descended from a population of Eurasian cave lions who crossed over into North America during the late Pleistocene. They may also be known from fossil material found in South America. Since Eurasian cave lions are known from cave art to have been maneless cats, it’s likely that even male American lions also lacked this feature. Given their large size, American lions would have been able to hunt many of the larger herbivorous mammals found in North America during the Pleistocene, bringing down bison, pronghorns, large deer, muskoxen and possibly even mammoths and mastodons. We know very little about their social structures but they may have lived and/or hunted together in prides like today’s lions. There is some evidence from cave paintings to suggest that their cave lion ancestors also lived in groups which may lend further credence to the idea that these American lions also spent time living together. (BELOW) Some bones belonging to American lions were recovered from the Natural Trap Cave site in Wyoming. These remains, comprising a skull, cervical vertebrae, pelvis, femur and ungual bones, are on display at the KU Museum Giant jaguar Panthera onca augusta Temporal Range: 1.8 million years ago to approximately 11,000 years ago Geographic Range: Found throughout North America Species: P. onca augusta Diet: Carnivorous, large mammalian prey The Giant Jaguar, Panthera onca augusta , was a large subspecies of jaguar once found as far north as Oregon. These animals are known from some fairly fragmentary remains but by scaling these fossils using the bones of living jaguars, it seems as though the largest members of this subspecies were up to 20% larger than their modern relatives, possibly as an adaptation for hunting larger prey in open habitats. Their legs are considerably longer than those of living jaguars, making them taller as well as more massive than their possible descendents. There are also trackways suggested to have been made by a giant jaguar in Tennessee at Blue Spring Cave. It is possible that the giant jaguar may be the direct ancestor of the living jaguar species found in parts of North and South America today. Today’s jaguars seem to have a preference for living in dense forests but they are also found in more open semi-arid environments. Some jaguars are even found today within the southernmost parts of the continental US. Smilodon fatalis Temporal Range: 700,000 years ago to approximately 11,000 years ago Geographic Range: Found across North America, possible South American material Species: S. fatalis, S. gracilis, S. populator Diet: Carnivorous, large mammalian prey Smilodon is the best known genus of saber-toothed cats. Smilodon fatalis was the dominant species in North America, descended from its smaller ancestor, the earlier Smilodon gracili s. Some Smilodon populations even managed to cross the Isthmus of Panama and reached South America, becoming their own separate species, Smilodon populato r. North American Smilodon found in the Midwest at the end of the Pleistocene epoch were slightly smaller than their relatives in South America but would still have been some of the largest cats found on the continent at that time. Their characteristic sabers seem to have been surprisingly fragile. Some fossils of Smilodon are occasionally found with broken saber teeth showing signs of wear indicating that they broke while the animal was still alive. Their exact purpose as part of Smilodon ’s hunting strategy remains a matter of debate with some suggesting that they may have been used in order to quickly sever blood flow in the necks of their prey. Although they are often colloquially referred to as “saber-toothed tigers”, Smilodon and other sabertooths were not particularly closely related to today’s lions and tigers. Sabertoothed cats are now classified within their own separate subfamily, Machairodontinae, which has no living members. Many of the later members of this group had very short tails. (BELOW) A Smilodon skeleton on display at the KU Natural History Museum. This skeleton is mounted in such a way that the mouth is open at nearly its maximum gape. These animals could have opened their mouths much wider than living pantherines in order to account for the length of their saber teeth. Dogs and Wolves (Canidae) Canids in the Midwest Canidae is the family of carnivoran mammals which includes today’s dogs, wolves, jackals, raccoon dogs and dholes. They are part of the caniform group of carnivorans meaning that they are more closely related to bears, weasels and otters than they are to cats or hyaenas. Most members of the canid family have long narrow snouts. They also have a set of large upper fourth premolars and a pair of specialized lower first molars used to cut through meat. During the Pleistocene epoch, the Midwest was home to some of the ancestors of today’s gray wolves and red wolves, as well as a variety of other extinct canids, most famously the dire wolf, Aenocyon dirus. Aenocyon armbrusteri Temporal Range: 850,000 years ago to approximately 13,000 years ago Geographic Range: Found across North America Species: A. armbrusteri Diet: Carnivorous, large mammalian prey Armbruster’s wolf was a species of canid found throughout North America during the Pleistocene epoch. Much like the dire wolf, these animals were originally placed within the genus Canis along with living dogs and wolves, but have since been placed within a separate genus; Aenocyon. Armbruster’s wolf shared many skeletal features in common with dire wolves and may in fact be the direct ancestor of Aenocyon dirus. Its fossils were first found in Maryland but remains belonging to Armbruster’s wolves have since been found throughout the US. It seems to have been most abundant during the early and middle Pleistocene epoch. Aenocyon dirus Temporal Range: 125,000 years ago to approximately 10,000 years ago Geographic Range: Found in parts of North and South America Subspecies: A. dirus dirus, A. dirus guildayi Diet: Carnivorous, large mammalian prey The dire wolf, Aenocyon dirus, was originally considered to be a close relative of the gray wolf, placed alongside it within the genus Canis . More recent analyses of their bones have suggested that dire wolves may have actually been part of a more distantly related lineage which diversified and spread throughout the Americas. This research led the dire wolf to be placed in a different genus, Aenocyon . In popular culture, dire wolves are usually represented as much larger versions of gray wolves. In reality, these animals were around the same height as the largest living gray wolves, although they were generally more heavily built than living wolves. Dire wolf remains are some of the most common mammal bones found at the La Brea Tar Pits in Los Angeles. Thousands of dire wolf bones have been found at this site, most likely drawn to the pits by the sounds of other animals who had already become trapped in the thick pools of tar. The sheer number of dire wolf remains found at these sites is considered evidence that these animals would have lived together in large packs, possibly using their numbers to bring down very large prey. Canis edwardii Temporal Range: 2.3 million years ago to approximately 300,000 years ago Geographic Range: Found throughout most of North America Species: C. edwardii Diet: Carnivorous, meat, invertebrates Edward’s wolf, Canis edwardii, is a canid with uncertain evolutionary relationships with other Pleistocene canids from North America. These animals are currently considered to be the ancestors of today’s coyotes. In terms of their size, Edward’s wolves were smaller than gray wolves but still quite a bit larger than living coyotes. Their snouts were long and thin and they seem to have been well adapted for hunting larger prey, unlike today’s coyotes which have a more generalist diet and feed primarily on smaller mammals and birds. Little is known about the social structures or possible pack sizes for Edward’s wolf. Media Gallery Suggested References: Carnivora Christiansen, P.; Harris, J. M. (2009). "Craniomandibular morphology and phylogenetic affinities of Panthera atrox: implications for the evolution and paleobiology of the lion lineage". Journal of Vertebrate Paleontology. 29 (3): 934–945. Christiansen, Per (2008). "Phylogeny of the great cats (Felidae: Pantherinae), and the influence of fossil taxa and missing characters". Cladistics. 24 (6): 977–992. Christiansen, Per; Harris, John M. (2005). "Body size of Smilodon (Mammalia: Felidae)". Journal of Morphology. 266 (3): 369–84. Eshelman, R. E.; Bell, C. J.; Graham, R. W.; Semken, H. A.; Withnell, C. B.; Scarpetta, S. G.; James, H. F.; Godfrey, S. J.; Mead, J. I.; Hodnett, J.-P.; Grady, F. V. (2025). "Middle Pleistocene Cumberland Bone Cave Local Fauna, Allegany County, Maryland: A Systematic Revision and Paleoecological Interpretation of the Irvingtonian, Middle Appalachians, USA". Smithsonian Contributions to Paleobiology. 108: 1–305. Fowler, Nicholas L.; Spady, Thomas J.; Wang, Guiming; Leopold, Bruce D.; Belant, Jerrold L. (2021). "Denning, metabolic suppression, and the realisation of ecological opportunities in Ursidae". Mammal Review. 51 (4): 465–481. Schubert, Blaine; Hulbert, Richard; MacFadden, Bruce; Searle, Michael; Searle, Seina (2010). "Giant Short-faced Bears (Arctodus simus) in Pleistocene Florida USA, a Substantial Range Extension". Journal of Paleontology. 84 (1): 79–87. Martin L. D.; Naples V. L; Babiarz J. P. (2011). "Revision of the new World Homotheriini". The Other Saber-tooths: Scimitar-tooth Cats of the Western Hemisphere. Baltimore: Johns Hopkins University Press. pp. 185–194. Meachen-Samuels, J.; Binder, W. (2010). "Sexual dimorphism and ontogenetic growth in the American lion and sabertoothed cat from Rancho La Brea". Journal of Zoology. 280 (3): 271–279. Meachen, Julie A.; O'Keefe, F. Robin; Sadleir, Rudyard W. (2014). "Evolution in the sabre-tooth cat, Smilodon fatalis, in response to Pleistocene climate change". Journal of Evolutionary Biology. 27 (4): 714–723. Perri, Angela R.; Mitchell, Kieren J.; Mouton, Alice; Álvarez-Carretero, Sandra; Hulme-Beaman, Ardern; Haile, James; Jamieson, Alexandra; Meachen, Julie; Lin, Audrey T.; Schubert, Blaine W.; Ameen, Carly; Antipina, Ekaterina E.; Bover, Pere; Brace, Selina; Carmagnini, Alberto (2021). "Dire wolves were the last of an ancient New World canid lineage". Nature. 591 (7848): 87–91. Rincón, Ascanio D.; Prevosti, Francisco J.; Parra, Gilberto E. (2011). "New Saber-Toothed Cat Records (Felidae: Machairodontinae) for the Pleistocene of Venezuela, and the Great American Biotic Interchange". Journal of Vertebrate Paleontology. 31 (2): 468–478. Schubert, Blaine; Kaufmann, James (2003). "A partial short-faced bear skeleton from an Ozark Cave with comments on the paleobiology of the species". Journal of Cave and Karst Studies. 65. Schubert, Blaine W.; Wallace, Steven C. (2009). "Late Pleistocene giant short-faced bears, mammoths, and large carcass scavenging in the Saltville Valley of Virginia, USA". Boreas. 38 (3): 482–492. Tedford, Richard H.; Wang, Xiaoming; Taylor, Beryl E. (2009). "Phylogenetic Systematics of the North American Fossil Caninae (Carnivora: Canidae)". Bulletin of the American Museum of Natural History. 325: 1–218. Van Valkenburgh, Blaire; Hayward, Matthew W.; Ripple, William J.; Meloro, Carlo; Roth, V. Louise (2016). "The impact of large terrestrial carnivores on Pleistocene ecosystems". Proceedings of the National Academy of Sciences. 113 (4): 862–867. Van Valkenburgh, B.; Sacco, T. (2002). "Sexual dimorphism, social behavior and intrasexual competition in large Pleistocene carnivorans". Journal of Vertebrate Paleontology. 22 (1): 164–169.

Learn more about the fossils of prehistoric animals by seeing them in 3D. These scans of Midwestern fossilized animal bones, including those of mammoths, dire wolves and sabertoothed cats, can be viewed from all angles to get a better idea of the forms of these fossils View fossils in 3D Scans and models of the remains of prehistoric life The models presented below are a series of scans taken of many different types of fossils which were generously provided by Bernard Means and the Virtual Curation Laboratory at Virginia Commonwealth University. To open these 3D scans, click on the model previews. You will then be able to click and drag in order to rotate and view the models from different angles. You can also find more models or further information about the VCL project by visiting the VCL website and Sketchfab page VCL Homepage VCL on Sketchfab American Mastodon (Mammut americanum) The American Mastodon was a large proboscidean found in North America from the end of the Miocene epoch to the end of the Pleistocene epoch. These animals tended to be shorter and stockier than mammoths and would have had cusped teeth used to break down woody vegetation. They also lack the domed forehead seen in the skulls of most mammoths. Learn more about Mastodons by visiting our entry about these animal in our Pleistocene Field Guide Mastodon Field Guide Entry Mastodon Right Molar 3 Description - (VCU_3D_2895): This mastodon molar was 3D scanned with a NextEngine Desktop 3D scanner at the Western Science Center’s Valley of the Mastodons workshop and conference in August 2017. The molar is from the Yukon and was brought from the Yukon Beringia Interpretative Center by Yukon Paleontonologist Grant Zazula. Specimen number YG 26.1. Courtesy of the Yukon Beringia Interpretative Center. Cohoes Mastodon Tusk Description - (VCU_3D_3634): This tusk of the Cohoes Mastodon was 3D scanned on May 31, 2018 with a Go!Scan 50 at the New York State Museum. Museum Specimen Number VP101. Courtesy of the New York State Museum. Cohoes Mastodon Skull Description - (VCU_3D_3632): This skull of the Cohoes Mastodon was 3D scanned on May 30 and May 31, 2018 with a Go!Scan 50 at the New York State Museum. Portions of the interior of the maxilla and mandible and the back of the skull could not be fully scanned because of the support structure for the skeletal mount. As the tusks were replicas, due to the fragile nature of the real tusks, these replica tusks were not 3D scanned. A planned return visit to the New York State Museum will attempt to capture additional 3D data from the skull. Museum Specimen Number VP101. Courtesy of the New York State Museum. Baby Mastodon Mandible Description - (VCU_3D_3209): This baby mastodon (Mammut americanum) mandible is from the Carter Bog site in Darke County, Ohio. It was 3D scanned with GoScan 50 at the Boonshoft Museum of Discovery. Courtesy of the Dayton Society of Natural History. Mammoths (M. columbi, M. primigenius) During the Pleistocene epoch North America would have been home to both Columbian mammoths and woolly mammoths. Woolly mammoths were found further north and Columbian mammoths were found as far south as southern Mexico. Separating the to can sometimes be complicated since populations of these species often interbred with one another Learn more about Mammoths by visiting our entries about these animals in our Pleistocene Field Guide Mammoth Field Guide Entries Mammoth Tusk Description - (VCU_3D_7852): The Randolph mammoth was discovered in May 1934 in Cattaraugus County, New York, near the town of Randolph. This tusk from a Colombian mammoth was 3-D scanned at the New York State Museum in May 2023 using a Go!Scan 50 3-D scanner. Courtesy of the New York State Museum. Randolph Mammoth Skull Description - (VCU_3D_3629): This mammoth skull is currently part of the Ice Ages exhibit at the New York State Museum. Because of this, the skull could only be 3D scanned with a Go!Scan 50 from the top and sides. A subsequent visit is anticipated to 3D scan the remainder of the fossil. Museum specimen number VP95. Courtesy of the New York State Museum. Mammoth molar Description - (VCU_3D_7842): This fossil was captured 11 May 2023 using a Go!Scan 50 at the New York State Museum. Courtesy of the New York State Museum which makes this model freely downloadable for non-commercial research, educational, and public outreach purposes. Dire Wolf (Aenocyon dirus) For most of the history of the study of their fossils, dire wolves were classified as members of the same genus as living wolves and dogs. More recent research seems to indicate that they were descended from their own line of canids who separately diversified in the Americas, leading to these animals being placed in a new genus, Aenocyon. Learn more about dire wolves by visiting our entry about these animals in our Pleistocene Field Guide Dire Wolf Field Guide Entry Dire Wolf Skull Description - (VCU_3D_3214): This dire wolf (Aenocyon dirus) wolf skull is from the La Brea tar pits but is in the collection of the Boonshoft Museum of Discovery. It was 3D scanned with a GoScan 50. The mandible is wired to the skull, which meant that portions of the skull could not be 3D scanned. Courtesy of the Dayton Society of Natural History. Smilodon fatalis Smilodon was a genus of saber-toothed cats once found in parts of North and South America. Among their closest relatives, Smilodon had some of the longest saber teeth, reaching over 10 inches long in some cases, including the root. These sabers seem to have been relatively fragile and fossils evidence shows that these delicate teeth sometimes broke while hunting. Learn more about Smilodon by visiting our entry about these animals in our Pleistocene Field Guide Smilodon Field Guide Entry Smilodon Skull Description - (VCU_3D_3615): This saber-toothed cat fossil is from the La Brea Tar Pits. It was originally cataloged as Smilodon californicus, a type usually subsumed today into Smilodon fatalis. The fossil was 3D scanned with a Go!Scan 50 at the Boonshoft Museum of Discovery on May 24, 2018. The mandible is wired to the cranium so not all aspects of the fossil could be properly 3D scanned. The fossil is real except for the canines, which are casts. Museum specimen G-28039. Courtesy of the Dayton Society of Natural History. Platygonus compressus Platygonus was an extinct type of peccary that was found in the Americas from the Miocene to the late Pleistocene epoch. These animals are sometimes called "flat-headed peccaries", a name which refers to the relatively uniform slopes of their nasal bones and the bones of their foreheads. Learn more about Platygonus by visiting our entry about these animals in our Pleistocene Field Guide Platygonus Field Guide Entry Platygonus Skull Description - (VCU_3D_3628): This skull of the extinct peccary (Platygonus compressus) was 3D scanned with a Go!Scan 50 at the New York State Museum on May 30, 2018. This skull is currently part of the Ice Ages exhibition. Museum specimen number VP46. Courtesy of the New York State Museum. Bison latifrons Bison latifrons , also known as the giant bison, was the largest bovid found in Pleistocene North America. Its horns could span over 7 feet across from tip to tip and they stood taller than an adult human at the shoulder. Weight estimates for these animals suggest that they could have grown to be as big as today's rhinos. Learn more about Bison latifrons by visiting our entry about these animals in our Pleistocene Field Guide Giant Bison Field Guide Entry Bison latifrons Skull Description - (VCU_3D_3937): This skull was found during construction of the Diamond Valley Lake near Hemet, California. It is currently on exhibit at the Western Science Center in Hemet. The skull was removed from its exhibit on September 10, 2018 for 3D scanning with a Go!Scan 50 and is associated with a horn. Courtesy of the Western Science Center. Bison latifrons Horn Description - (VCU_3D_3936): This horn was found during construction of the Diamond Valley Lake near Hemet, California. It is currently on exhibit at the Western Science Center in Hemet. The horn was removed from its exhibit on September 10, 2018 for 3D scanning with a Go!Scan 50 and is associated with a skull. Courtesy of the Western Science Center. Bootherium bombifrons The woodland muskox, Bootherium bombifrons, was a type of muskox that once lived in parts of the Midwest and the Great Plains. Although they look very similar to bison or cows, the closest relatives of muskoxen are actually sheep and goats. The horns over their foreheads were joined together along the middle of the skull instead of being separated by an open gap. Learn more about Bootherium by visiting our entry about these animals in our Pleistocene Field Guide Bootherium Field Guide Entry Bootherium Skull Description - (VCU_3D_4139): This skull of a Bootherium bombifrons is the holotype and was collected by William Clark and George Rogers Clark from Big Bone Lick, Kentucky for Thomas Jefferson. It was 3-D scanned with a Go!Scan 50 at the Academy of Natural Sciences in Philadelpha on December 10, 2018 with funding from a Virginia Commonwealth University (VCU) Seed Grant entitled “3-D Digital Ice Age Mastodon and Mammoth Skeletal Remains.” Specimen number 12994. Courtesy of the Academy of Natural Sciences. Castoroides ohioensis Castoroides, also known as the giant beaver, was possibly the largest rodent ever to live in North America. It could probably have grown to be as heavy as a black bear and each of its incisors was over five inches long. These animals do not seem to have been adapted for cutting down trees and instead would have browsed on aquatic vegetation in ponds and lakes. Learn more about Castoroides by visiting our entry about these animals in our Pleistocene Field Guide Castoroides Field Guide Entry Castoroides Skull Description - (VCU_3D_3639): This giant beaver skull was 3D scanned with a Go!Scan 50 at the New York State Museum on May 31, 2018. It was found in Wayne County, New York. Museum Specimen Number VP 47. Courtesy of the New York State Museum. Megalonyx jeffersonii Megalonyx was a type of ground sloth once found across most of North America all the way up until the very end of the Pleistocene epoch. Unlike many other types of ground sloths, who often walked on the sides of their feet, Megalonyx would have walked with the soles of its feet planted on the ground. It had a short snout and distinctive tusk-like insisors Learn more about Megalonyx by visiting our entry about this sloth in our Pleistocene Field Guide Megalonyx Field Guide Entry Megalonyx Skull Reconstruction Description - (VCU_3D_3996): Reconstructed skull of a Megalonyx by Ray Voden of the Virginia Museum of Natural History based on a fossil found at the Carter Bog site in Ohio and held at the Boonshoft Museum of Discovery. The red portions are reconstructed while the non-red portions are a cast of the original fossil. It was 3-D scanned with a GoScan! 50 on October 19, 2018. Courtesy of the Dayton Society of Natural History and the Virginia Museum of Natural History. Megalonyx Claw With Nail Description - (VCU_3D_5214): This giant ground sloth (Megalonyx jeffersonii) with intact finger nail was recovered from Big Bone Cave, Tennessee. It was 3-D scanned with a NextEngine Desktop 3-D scanner on March 11, 2020 at the Academy of Natural Sciences in Philadelphia. Repository specimen number ANSP 12487. Courtesy of the Academy of Natural Sciences. The Virginia Commonwealth University Humanities Research Center supported the research trip that made this scanning effort possible. Megalonyx Mandible Descritption - (VCU_3D_3943): This giant ground sloth mandible is currently on exhibit at the Western Science Center. It was removed from the exhibt for 3D scanning on September 10, 2018 and was 3D scanned with a Go!Scan 50. Courtesy of the Western Science Center. Paramylodon harlani Paramylodon harlani, also known as Harlan's ground sloth, was a large terrestrial sloth native to North America. It had a fairly long snout and is well represented by dozens of skeletons found at the Rancho La Brea Tar Pits in Los Angeles. Footprints of a Paramylodon were also found in associated with human tracks at White Sands National Monument. Learn more about Paramylodon by visiting our entry about this sloth in our Pleistocene Field Guide Paramylodon Field Guide Entry Paramylodon Osteoderm Description - (VCU_3D_8386): This fossil was 3-D scanned with a NextEngine Desktop scanner on 10 December 2024. Courtesy of Kevin Jones who has agreed to make this 3-D scan freely downloadable for non-commercial educational, outreach, and research purposes. A small plate of bony armor which would have been embedded in the skin of the sloth in life. Paramylodon Claw Description - (VCU_3D_3090): This fossil was 3D scanned at the Western Science Center on December 14, 2017 using a NextEngine Desktop 3D scanner. Courtesy of the Western Science Center. Find out more about ice age animals in the Midwest by exploring our Pleistocene field guide Learn More

Explore the different types of small sharks who lived during the Cretaceous period in the Western Interior Sea, including ground sharks, angel sharks and dogfishes Sharks (continued) Sharks Not all sharks are listed on this page. See the list below for the order in which shark entries are listed Previous Page This page Order Orectolobiformes Chiloscyllium Cretorectolobus Orectoloboides Plicatoscyllium Order Lamniformes Archaeolamna “Carcharias” Cardabiodon Cretolamna/Cretalamna Cretodus Cretoxyrhina Dallasiella Johnlongia Leptostyrax Odontaspis Paranomotodon Protolamna Pseudocorax Pseudomegachasma Ptychodus Scapanorhynchus Squalicorax Previous Page Order Carcharininiformes Archaeotriakis Galeorhinus Palaeogaleus Squatigaleus Order Synechodontiformes Paraorthacodus Synechodus Order Squatiniformes Squatina Order Heterodontiformes Heterodontus Order Squaliformes Squalus Order Hexanchiformes Hexanchus Unclear Affinities Aquilolamna Ground sharks (Carchariniformes ) Cat Sharks, Hound Sharks Carcharhiniform sharks are an order of sharks commonly known as the ground sharks. This group represents the most diverse order of living sharks and includes tiger sharks, bull sharks and hammerheads. Like many types of true sharks, these animals have five gill slits, an anal fin, two dorsal fins lacking spines and a nictitating membrane that protects their eyes while biting into their prey. The members of this group have highly variable tooth shapes depending on their ecological niche, ranging from long thin teeth for catching small fish to the blade-like teeth of the tiger shark. Fossils of carchariniform shark teeth are less common in rock layers from the Western Interior Sea than the remains of their lamniform cousins. Many of the roles occupied by today’s requiem sharks and larger ground sharks were filled by these extinct mackerel shark genera, and most remains of Cretaceous ground sharks seem to be those of smaller animals. Nevertheless, a few genera known from fairly complete skeletal remains dating back to the Cretaceous still have living members found in the world’s oceans today. Archaeotriakis Temporal Range: 75 million years ago Geographic Range: Wyoming, Canada, Montana Species: A. rochelleae, A. ornatus Diet: Carnivorous, fish, small invertebrates Archaeotriakis was a small prehistoric carcharhiniform shark which is considered a member of the false catshark family Pseudotriakidae. Its teeth were tiny but strongly built, with large central cusps with two smaller cusps on each side. The largest of these side cusplets are still about half the size of the main cusp of the tooth. These teeth also had distinct ridges running vertically along the lower margins of their cusps. The main cusps of these teeth are shorter than those found in many other types of sharks. Some features of its teeth look a lot like those of early ancestral ground sharks, while others, such as the unusually large side cusps and curved cutting edges, are rarely seen in related species. This may be a sign that Archaeotriakis would have occupied a unique role in the marine ecosystem and possibly fed on different types of prey than other carcharhiniform sharks. Its fossils are found in areas which would have been near the coastline in shallow waters and possibly in estuarine or nearshore river environments. Galeorhinus Temporal Range: 97 million years ago - present Geographic Range: Worldwide distribution Species: G. cuvieri, G. duchaussoisi, G. girardoti, G. glickmani, G. louisi, G. muelleri, G. tenius, G. galeus Diet: Carnivorous, fish, cephalopods Galeorhinus is an extant genus of hound shark whose fossil remains are also known from the Cretaceous period. They are also known as school sharks. These animals have very long, narrow snouts. Their mouths are broad and curved, and the teeth in both jaws are very similar in size and shape. These teeth are small, triangular and flat when viewed from the side. The distal edge of each tooth is covered in a row of prominent serrations. These teeth seem to be suited both for catching and cutting through soft-bodied prey. The bodies of these sharks are long and narrow and the first dorsal fin is located just behind the pectoral fins, while the second dorsal fin is nearly equal in size to the anal fin and positioned directly above it. These sharks are known from many different species found from the middle Cretaceous period onwards but only one species is found today, Galeorhinus galeus . Palaeogaleus Temporal Range: Late Cretaceous, parts of the Paleogene Geographic Range: Parts of North America, Europe, Africa Species: P. navarroensis, P. larachei Diet: Carnivorous, fish, cephalopods Palaeogaleus was an extinct hound shark. Its teeth were generally small and narrow, roughly similar to those of animals like Galeorhinus , with a sharp central cusp and smaller cusps on either side. Compared with the larger, broader cutting teeth found in many larger carcharhiniform sharks, the teeth of Palaeogaleus appear to have been better suited for catching and holding smaller prey. These animals are some of the first members of the houndshark family Triakidae to appear during the late Cretaceous period. The genus has no living members. Squatigaleus Temporal Range: 75 million years ago - 66 million years ago Geographic Range: Central North America, parts of Europe and Africa Species: S. sulphurensis Diet: Carnivorous, fish, sharks, marine reptiles Squatigaleus was a rare extinct carcharhiniform shark that is known mainly from fossil teeth found in Late Cretaceous rocks. The best-known species is Squatigaleus sulphurensis which has been identified from fossil deposits in Texas and is classified within the hound shark family, Triakidae. Its teeth are quite different from those of other types of hound sharks. These teeth have much more prominent main cusps which are very wide and slightly curved when viewed from the side. Based on the size of their teeth and the appearances of their living relatives, Squatigaleus was probably a smaller shark with a long, thin body. Synechodontiformes Synechodontiformes is an order of cartilaginous fishes which has its origins in the Permian period and which managed to survive past the end-Cretaceous mass extinction event all the way up until the middle of the Paleogene period. Their exact classification within the cartilaginous fish family tree remains a subject of debate. They are sometimes considered to be true members of the shark division Selachii as an early line branching off from the Galean sharks. Other studies consider them to fall outside of the true shark group and instead recover them as a separate group which spilt off from the common ancestors of sharks and rays. Synechodus Temporal Range: Triassic to the early Paleogene, possible Permian record Geographic Range: North America, parts of Europe and eastern Russia Species: S. dubrisiensis, S. antiquus? Diet: Carnivorous, fish, cephalopods Synechodus is a very old genus of sharks, with the first members of this genus dating back to the early Triassic and possibly parts of the Permian period. In addition to fossils of its teeth, some Synechodus fossils preserve the shape of the animal’s entire body. Synechodus teeth had a thin central cusp flanked by three to five smaller cusps on each side. These teeth were better suited for grasping and holding prey than for cutting large pieces of flesh. The roots of the teeth were very wide but very thin with a gentle curve positioned beneath the area supporting the main cusp of each tooth. Fossil skeletons show that Synechodus had a broad head, a rounded snout, and large pectoral fins attached to a relatively compact body. It had a single dorsal fin positioned further along the animal’s back which did not feature the defensive fin spines seen in some ancient shark groups. Paraorthacodus Temporal Range: 200 million years ago - 37 million years ago Geographic Range: Worldwide distribution Species: P. andersoni, P. antarcticus, P. clarkii, P. conicus, P. eocaenus, P. jurensis, P. nerviensis, P. patagonicus, P. recurvus, P. sulcatus, P. validus, P. helveticus Diet: Carnivorous, fish, cephalopods Paraorthacodus was a genus of shark very similar to the related genus Synechodus. Some fossils are known from this genus which preserve the entire shape of the animal's body which show us that, like many of its relatives, these animals would have had blunt, rounded snouts, short fins and a dorsal fin located further along the animal’s back. Their teeth were similar to those of Synechodus but can be distinguished by the order of the sizes of their lateral cusplets, which decrease in size more slowly than those of their relatives as they move further away from the main tooth cusp. Angelsharks (Squatiniformes ) Angelsharks are a very unique group of sharks who are adapted to spend their lives as ambush hunters, partially burying themselves on the seafloor. Their bodies are roughly similar to those of electric rays or guitarfishes, although the arrangement of their teeth and positions of the gill slits indicate that they are, in fact, members of the true shark group. Their pectoral fins are quite large and they join up with the body just below the base of the head. The rest of their bodies are extremely flat and dorso-ventrally compressed. Squatina Temporal Range: 118 million years ago - Present Geographic Range: Worldwide distribution Species: S. cranei, S. prima, S. crassa, S. minor, S. baumbergensis Diet: Carnivorous, fish, benthic invertebrates The genus Squatina is a type of angel shark. This group of sharks is rather strange since its members resemble rays more than they look like typical sharks. Instead of having the streamlined body shape seen in most sharks, angel sharks have broad, flattened bodies and large, wing-like pectoral and pelvic fins. This body design allows them to rest comfortably on the seafloor and remain well camouflaged in sandy or muddy habitats. Even though they look similar to rays they still have many important features found in other sharks, including a muscular tail, two dorsal fins, and gill slits positioned along the sides of their heads. There are several species of Squatina angelsharks found in today’s oceans but their fossil record dates all the way back to the early Cretaceous. Although they are rare in the central US, their fossils are occasionally found in deposits formed by the Western Interior Sea. Angel sharks are ambush predators. Rather than swimming actively in search of prey angel sharks spend much of their time lying motionless on the seabed. They often cover themselves in a thin layer of sediment to add to their disguises. With only their eyes and spiracles visible they can remain hidden until a fish or other prey item comes within range. Bullhead sharks (Heterodontiformes ) Bullhead sharks are a group of cartilaginous fishes whose first fossil remains date back to the Jurassic period. These tend to be rather small sharks who specialize in feeding on benthic invertebrates near the seafloor. They have eyes which are positioned above their bodies and dorsal fins which are equipped with sharp protective spines. Heterodontus Temporal Range: ~155 million years ago - Present Geographic Range: Worldwide distribution Species: H. rugosus Diet: Carnivorous, fish, marine invertebrates The genus Heterodontus is a group of sharks commonly known as bullhead sharks. These animals are used for their very unique teeth and mouthparts which are quite different from those of large macropredatory sharks. The teeth at the front of their jaws are sharp and pointed so that the shark can hold on to its prey while the teeth at the back of the mouth are more broad and flattened for crushing hard-shelled animals such as sea urchins, crabs, and mollusks. This combination of different tooth types is uncommon among sharks and is the reason for the name Heterodontus, which means “different teeth.” These animals are also easily identifiable thanks to the shape of their heads. They have a short, blunt snout and prominent ridges above their eyes that look like small horns. They also have two dorsal fins, each supported by a strong spine. These dorsal fin spines are a feature that is rare among modern sharks but is found in many types of extinct sharks and shark relatives. They likely provide protection from predators. Dogfish (Squaliformes ) Dogfishes as a group of relatively small sharks which show up at the start of the Cretaceous period. They are easily distinguished from other types of sharks by their lack of an anal fin in between their pelvic fins and caudal fluke. Living dogfish sharks are known to travel extremely long distances, in some cases for thousands of miles, as part of migrations or in search of food. They usually feed on soft-bodied prey animals Squalus Temporal Range: 89 million years ago - Present Geographic Range: Worldwide distribution Species: S. ballingsloevensis Diet: Carnivorous, fish, cephalopods Squalus is a genus of dogfish sharks. These are a smaller variety of sharks which have long, thin bodies. Members of this genus also have a sharp spine located in front of each of their two dorsal fins. These spines give them some extra protection from predators and are one of the defining traits of the genus. These animals also do not have an anal fin. Squalus sharks also have a slender body, a pointed snout, and relatively uniform teeth in both the upper and lower jaws. Unlike sharks with highly specialized teeth for cutting or crushing, dogfish sharks have sharp, blade-like teeth that are well suited for capturing and eating small fishes and invertebrates. Sixgill sharks (Hexanchiformes ) Sixgill sharks, which are still found in the world's oceans today, first appear in the fossil record during the early Cretaceous period. Their tooth fossils are fairly rare in Cretaceous deposits from the Western Interior Sea but they may have spent their lives hunting at the bottom of deeper areas in the sea, much like their living descendants. Hexanchus Temporal Range: 110 million years ago - Present Geographic Range: Worldwide distribution Species: H. agassizi, H. andersoni, H. casieri, H. gracilis, H. microdon Diet: Carnivorous, fish, sharks, marine reptiles The genus Hexanchus is a group often known as the sixgill sharks. As their name suggests, Hexanchus had six gill slits on each side of its body. Most modern sharks have only five gill slits, making this extra pair a key feature that separates sixgill sharks from nearly all other shark groups. Hexanchus species have only one dorsal fin instead of the two found in most other extant sharks. This genus is particularly old among extant true sharks and their strange anatomical features hint at their separation from most other branches on the shark family tree. Their tooth shape and arrangement is also rather odd. The lower jaw contains large, comb-shaped teeth with multiple sharp cusps, while the upper jaw is lined with smaller, narrower teeth. This arrangement makes it easier for sixgill sharks to grip and tear apart a variety of prey. Unlike most shark species that are commonly found in shallow coastal waters, Hexanchus sharks are primarily deep-water animals. Their fossil teeth occasionally show up in Cretaceous rocks linked to the presence of the Interior Sea. Unclear affinities Aquilolamna Temporal Range: 93 million years ago Geographic Range: Central Mexico Species: A. milarcae Diet: Filter feeder, plankton, copepods, algae Aquilolamna is a very strange type of shark whose body shape was only recently revealed. Fossils showing the anatomy of the animal’s entire body have been recovered from the Agua Nueva Formation in Mexico, which sat just below the southern edge of the Western Interior Sea during the Late Cretaceous. These animals had a body design unlike that of any shark living today. Although it had the streamlined body and tail typical of sharks, its most striking feature was its enormous wing-like pectoral fins. These fins were so large that the animal's wingspan exceeded its body length which gave it an appearance more similar to that of a manta ray than a traditional shark. This combination of shark and ray-like characteristics makes Aquilolamna unique among known elasmobranchs. These animals also seem to have a diet similar to that of today’s manta rays, with its small teeth and relatively wide mouth possibly suggesting that it was a filter feeder that fed on plankton in open water. See the rest of our entries about Cretaceous sharks by returning to the previous page Previous Page Media Gallery Suggested References: Sharks Case,G. R.;H. Cappetta. (1997). “A new Selachian Fauna from the Late Maastrichtian of Texas” (Upper Cretaceous/Navarroan; Kemp Formation) . Münchner Geowiss. Abh. (A)(34):131–189 Cook, T.D.; Newbrey, M.G.; Murray, A.M.; Wilson, M.V.H.; Shimada, K.; Takeuchi, G.T.; Stewart, J.D. (2011). "A partial skeleton of the Late Cretaceous lamniform shark, Archaeolamna kopingensis, from the Pierre Shale of western Kansas, U.S.A.". Journal of Vertebrate Paleontology. 31 (1): 8–21 Everhart, M. J. (2004). “Late Cretaceous interaction between predators and prey. Evidence of feeding by two species of shark on a mosasaur”. PalArch, vertebrate palaeontology series 1(1):1-7. Everhart, M.J. (2017). “Oceans of Kansas - A Natural History of the Western Interior Sea”, Second Edition. Indiana University Press, 460 pp. Everhart, M. J. (2005). “Bite marks on an elasmosaur (Sauropterygia; Plesiosauria) paddle from the Niobrara Chalk (Upper Cretaceous) as probable evidence of feeding by the lamniform shark, Cretoxyrhina mantelli”. PalArch, Vertebrate paleontology 2(2): 14-24. Everhart, M. J. and K. Ewell. (2006). “Shark-bitten dinosaur (Hadrosauridae) vertebrae from the Niobrara Chalk (Upper Coniacian) of western Kansas”. Kansas Academy of Science, Transactions, 109 (1-2):27-35. Jambura, P.L.; Stumpf, S.; Kriwet, J. (2021). "Skeletal remains of the oldest known pseudocoracid shark Pseudocorax kindlimanni sp. nov. (Chondrichthyes, Lamniformes) from the Late Cretaceous of Lebanon". Cretaceous Research. 125 Lucas, S. G.; Sullivan, R. M. (2006). “Late Cretaceous Vertebrates from the Western Interior: Bulletin 35.” New Mexico Museum of Natural History and Science. Maisey, J. G., (1996). Discovering Fossil Fishes. Henry Holt and Company, New York. McAllister, J. A. (1985). “Reevaluation of the formation of spiral coprolites” - University Kansas Paleontology Contributions, Paper 114, 12 p. McIntosh, A. P.; Shimada, K.; Everhart, M. J. (2016). "Late Cretaceous marine vertebrate fauna from the Fairport Chalk Member of the Carlile Shale in southern Ellis County, Kansas, U.S.A." Transactions of the Kansas Academy of Science. Schwimmer, D. R., J.D. Stewart, and G. D. Williams. (1997). “Scavenging by sharks of the genus Squalicorax in the late Cretaceous of North America”. PALAIOS, 12:71-83. Shimada, K. (2007). "Skeletal and dental anatomy of lamniform shark, Cretalamna appendiculata from Upper Cretaceous Niobrara Chalk of Kansas". Journal of Vertebrate Paleontology, 27(3):584–602. Shimada, K. (2008). “Ontogenetic parameters and life history strategies of the Late Cretaceous lamniform shark, Cretoxyrhina mantelli, based on vertebral growth increments”. Journal of Vertebrate Paleontology 28(1):21-33. Shimada, K. and Cicimurri, D.J. (2005). “Skeletal anatomy of the Late Cretaceous shark, Squalicorax (Neoselachii: Anacoracidae).” Paläontologische Zeitschrift 79(2): 241-261. Shimada, K and M. J. Everhart. (2003). “Ptychodus mammillaris (Elasmobranchii) and Enchodus cf. E. schumardi (Teleostei) from the Fort Hays Limestone Member of the Niobrara Chalk (Upper Cretaceous) in Ellis County, Kansas”. Kansas Academy of Science, Transactions 106(3-4):171-176. Shimada, K. and M. J. Everhart. (2004). “Shark-bitten Xiphactinus audax (Teleostei: Ichthyodectiformes) from the Niobrara Chalk (Upper Cretaceous) of Kansas”. The Mosasaur 7, p. 35-39. Shimada, K. and D. J. Martin. (1993). “Upper Cretaceous selachians from the basal Greenhorn Limestone in Russell Co., Kansas”. Kansas Academy of Science Abstracts, 12(78). Shimada, K. (1993). Upper Cretaceous selachians from the Fort Hays Limestone Member of the Niobrara Formation in Ellis County, Kansas. Kansas Academy of Science Abstracts, 12(78). Shimada, Kenshu; Ewell, Keith; Everhart, Michael J. (2004). "The First Record of the Lamniform Shark Genus, Johnlongia, from the Niobrara Chalk (Upper Cretaceous), Western Kansas". Transactions of the Kansas Academy of Science. 107 (3/4): 131–135. Shimada, Kenshu; Popov, Evgeny V.; Siversson, Mikael; Welton, Bruce J.; Long, Douglas J. (2015). "A new clade of putative plankton-feeding sharks from the Upper Cretaceous of Russia and the United States". Journal of Vertebrate Paleontology. 35 (5) Shimada, Kenshu; Everhart, M.J. (2019). "A new large Late Cretaceous lamniform shark from North America, with comments on the taxonomy, paleoecology, and evolution of the genus Cretodus". Journal of Vertebrate Paleontology. 39 (4) Siverson, M. and J. Lindgren. (2005). “Late Cretaceous sharks Cretoxyrhina and Cardabiodon from Montana, USA”. Acta Palaeontol. Pol. 50(2) 301-314. Underwood, C.J.; Cumbaa, S.L. (2010). "Chondrichthyans from a Cenomanian (Late Cretaceous) bonebed, Saskatchewan, Canada". Palaeontology. 53 (4): 903–944. Welton, B. J., and R. F. Farish (1993). "The Collector's Guide to Fossil Sharks and Rays from the Cretaceous of Texas." Before Time, Lewisville, Texas, 204 pp. Williamson, T. E., J. I. Kirkland and S. G. Lucas. (1993). “Selachians from the Greenhorn cyclothem ("Middle" Cretaceous: Cenomanian-Turonian), Black Mesa, Arizona, and the paleogeographic distribution of Late Cretaceous selachians”. J. Paleon. 67(3):447-474.

Explore the different types of prehistoric coelacanths who lived in the Western Interior Sea during the Cretaceous period. Coelacanths Lobe-Finned Fishes of the Western Interior Sea Compared with earlier geological periods, coelacanth diversity had declined quite a lot by the Late Cretaceous. However, despite this they continued to occupy a role within marine ecosystems alongside other vertebrates inhabiting the Western Interior Sea. Fossil evidence indicates that one of the largest known coelacanths of all time, Megalocoelacanthus, was found in the Interior Sea at this time. These animals would have been fearsome, albeit fairly slow moving, predatory animals who preyed upon smaller fishes and even mid-sized marine reptiles. Anatomy Skeletal Anatomy Coelacanths have a series of strong bones at the bases of their fins which support the muscles of their fin lobes. Some of these bony structures contain the bones which are homologous with the bones in the arms and legs of tetrapods. Most coelacanths also keep a large spinal notochord throughout adulthood. Unlike the fully developed vertebral columns of most modern bony fishes, the coelacanth's notochord remains as a fluid-filled, supportive rod running along the body in place of a bony spine. At the front of their skulls they have a special rostral organ which allows these fishes to pick up electrical signals left by their prey. The outer parts of the bodies of coelacanths are covered in a coat of mineralized scales. Much of their skeleton consists of cartilage rather than dense bone, reducing weight while maintaining structural support. Their tails are tri-lobed and have a small central extension along the middle of the caudal fin set known as the epicaudal lobe. (BELOW) A labeled diagram of the skeleton of a coelacanth. Note the presence of a very large notochord running along the length of the animal in the place of a spine. This notochord is an unusual feature among members of the bony fish group Evolutionary History Lobe-finned fishes are a group of vertebrate animals with bony ossified skeletons and whose earliest members had/have fleshy, bone-supported paired fins. These fins each have a muscular lobe at their bases instead of having fins composed only of sets of long thin rays as in ray finned actinopterigian fishes. The main three groups of lobe-finned fishes are the coelacanths, the lungfishes, and the tetrapods, including most terrestrial vertebrates. Coelacanths are the best known type of lobe-finned fishes. Although they are only found in deep waters today, their predecessors lived in shallow water and riparian environments for millions of years. This lineage first showed up during the early Devonian but they suffered a massive drop in species diversity at the end of the Cretaceous period. Lungfishes are another type of lobe-finned fish. These animals are able to breathe air for short periods of time. Despite this air breathing ability these lungfishes are not ancestral to the other group of air-breathing lobe-finned fishes, the tetrapods. Tetrapods, including all reptiles, amphibians, birds and mammals, are all descended from aquatic lobe-finned fish ancestors. As such this group is by far the most abundant lineage of lobe-finned fish. (BELOW) The main living groups of lobe-finned fishes include coelacanths, lungfishes and tetrapods. This technically means that all terrestrial vertebrates are part of the lobe-finned fish clade. Megalocoelacanthus Temporal Range: 87 million years ago - 66 million years ago Geographic Range: Kansas Species: M. dobei Diet: Carnivorous, fish, cephalopods, marine reptiles Megalocoelacanthus was a very large genus of coelacanths that lived in the Late Cretaceous seas of North America. It has been estimated to have grown to be up to 15 feet long, which would make it one of the largest coelacanths known from the fossil record. Fossils recovered from the Niobrara Formation of Kansas show that these animals had a narrow parietonasal shield bordered by unusually large openings on the sides of its head that housed parts of the supraorbital sensory canal system. A similar skull arrangement is seen only in a few closely related genera, including the genus Libys from the Jurassic period. Megalocoelacanthus also seems to have been largely edentulous, meaning that it probably had very few teeth. Some mawsoniid coelacanths also have this toothless feature but these two animals seem to be fairly distantly related to one another and Megalocoelacanthus is currently positioned as a closer relative of the living coelacanth genus Latimeria. Suggested References: Coelacanths Brito, Paulo M.; Meunier, François J.; Clément, Gael; Geffard-Kuriyama links, Didier (2010). "The histological structure of the calcified lung of the fossil coelacanth Axelrodichthys araripensis (Actinistia: Mawsoniidae)". Palaeontology. 53 (6): 1281–90. Dutel, H., Maisey, J., Schwimmer, D., Janvier, P. and Clément, G. (2011). “Giant coelacanth Megalocoelacanthus dobiei from the Upper Cretaceous of North America and its bearings on the phylogeny of Mesozoic coelacanths”. Journal of Vertebrate Paleontology 31 Everhart, M.J. (2017). “Oceans of Kansas - A Natural History of the Western Interior Sea,” Second Edition. Indiana University Press, 460 pp. Fricke, H.; Plante, R. (1988). "Habitat requirements of the living coelacanth Latimeria chalumnae at grande comore, Indian Ocean". Naturwissenschaften. 75 (3): 149–51. Schwimmer, D. R., Stewart, J.D. and Williams, G.D. (1994). “Giant fossil coelacanths of the Late Cretaceous in the eastern United States”. Geology. 22:503-506.

Explore the types of octopus relatives, belemnites and nautiloids who lived in the Western Interior Sea during the Cretaceous period Coleoids and Nautiloids Octopods and Nautiloids of the Western Interior Sea In addition to the more common fossils of ammonoid shells, deposits laid down by the Cretaceous Western Interior Sea hold the fossils of two more groups of cephalopods. One of these groups is the nautiloids whose members have rounded and tightly coiled external shells divided into chambers. Their simple shell sutures separate them at a glance from the elaborate shell divisions of ammonites. Coleoids, on the other hand, are the lineage containing modern squid, octopuses, and cuttlefish. These animals do not have an external shell and as a result the fossil record for these animals is made up mostly of smaller hard elements from the internal parts of their bodies and occasionally the remains of hook-like structures from their arms and tentacles. Most members of this second group are thought to have been active hunters much like their living relatives. Coleoid Anatomy Internal and External Tissues Coleoids have soft bodies which are organized around a muscular mantle which surrounds the internal organs. By drawing water into the mantle cavity and forcing it through the flexible funnel of the hyponome, many coleoids can push themselves through the water using a process which somewhat resembles jet propulsion. They have complex eyes and their mouths are surrounded by a sharp beak. Inside of their mouths they have a radula which is used to break up their food. Coleoids have a series of muscular arms covered in suckers and/or hooks. Squids and cuttlefish generally have eight arms plus two elongated feeding tentacles, whereas octopods have eight arms and no separate tentacles. Unlike nautiloids, coleoids do not have a large external shell. Some still have an internal shell, such as the squid’s gladius or the cuttlefish’s chambered cuttlebone, while some octopods have a set of small hard structures beneath their mantles which are called stylets. Belemnites, another type of coleoid, have bullet shaped rostra at the very tips of their bodies in front of their fins. Many of the larger extinct muensterellid coleoids who are fairly well represented in the fossil record from this time period had internal gladii and external anatomies which at first look a lot like those of squids, although they are now currently considered to be a group of stem-octopods. (BELOW) A labeled diagram of the external anatomy of the muensterellid coleoid Muensterella showing the features seen in many types of Cretaceous stem-octopods (BELOW) The hard tissue elements of the body of a squid, including a large elongated gladius and a small beak (BELOW) The hard tissue elements found in today's octopi. Not all octopi have stylets but these represent the last remaining portions of the shells which were found in basal cephalopods. In Cretaceous stem-octopods, the mantle usually houses a large gladius which appears roughly similar to that of a squid. (BELOW) The hard tissue elements found in extinct belemnite cephalopods. In addition to the fossils of the solid rostrum, some of these animals are known from fossils which preserve the remains of hook-like structures on their arms. Coleoids and Nautiloids (Browse by subclass) Subclass Coleoidea Belemnites Enchoteuthis Muensterella Niobrarateuthis Subclass Nautiloidea Stenzeloceras Eutrephoceras Cymatoceras Belemnites Temporal Range: 234 million years ago - 66 million years ago Geographic Range: Worldwide distribution Genera in the Western Interior Sea: Actinocamax, Belemnitella Diet: Active pelagic predator, small fish and invertebrates Belemnites are a group of cephalopods who first show up during the Triassic period and were some of the most abdundant pelagic mollusks of the Mesozoic era. They are best known from fossils of their rostra, which are bullet-shaped hard tissue elements positioned in front of the animal's side fins in life. Belemnites would have appeared very similar to squid from the outside, although the long rostral proifiles of some belemnites groups would have given them a distinctive elongated and pointed appearance which is not seen in any type of extant cephalopod. These animals most likely dissapeared during the end-Cretaceous extinction, (BELOW) A pair of belemnite rostrum fossils on display the the KU Natural History Museum. The rostra of different types of belemnites can vary a lot between different families, both in terms of their cross-sections and the presence/absence of grooves or furrows along the margins of the structure. Enchoteuthis Temporal Range: Early and Late Cretaceous, Albian - Campanian stages Geographic Range: Central North America, Australia Species: E. melanae, E. tonii, E. cobbani Diet: Active pelagic predator, small fish and invertebrates Enchoteuthis was a large stem-octopod which lived out in the open waters of the Western Interior Sea. These animals are mostly known from gladius fossils of an elongated spear-like internal structure that supported its mantle. Because fossils usually preserve only this structure, scientists know little about its softer anatomy, including its arms and possible tentacles. It used to be restored to appear similar to a living giant squid but more recent findings have shown that it probably was more similar to the smaller Muensterella . It had a torpedo-shaped body, short fins, eight arms and no long tentacles. It likely fed upon small to medium-sized fishes, cephalopods and possibly even small marine reptiles. Most fossils formerly assigned to the more famous genus Tusotheuthis are now classified under the Enchoteuthis genus. (BELOW) A large fossil gladius (center frame) from the Cretaceous period of Kansas on display at the KU Natural History Museum. This particular fossil is well over 3 feet long and most likely comes from an Enchoteuthis Muensterella Temporal Range: 155 million years ago - 90 million years ago Geographic Range: Texas, parts of Europe, Antarctica Species: M. scutellaris, M. spinosa Diet: Active pelagic predator, small fish and invertebrates Muensterella was an extinct coleoid which would have looked a lot like a cuttlefish or bobtail squid, despite more fossil evidence pointing towards it being closer to octopuses and vampire squids. Aside from the more common fossils of their gladii, some fossils of these animals found in fine-grained limestone preserve traces of soft tissue, including the remains of tentacles and even internal organs. The genus is unusually well documented compared with many other prehistoric coleoids which typically begin to decompose shortly after death and leave behind very few hard remains. Niobrarateuthis Temporal Range: 89 million years ago Geographic Range: Kansas Species: N. bonneri Diet: Active pelagic predator, small fish and invertebrates Niobrarateuthis was a muensterellid stem-octopod which had a gladius with a wide, spoonlike end called the patella. This characteristic links the animal to early relatives of modern octopuses. However, its complete appearance remains uncertain because delicate structures such as the arms, eyes, beak, and muscles were rarely fossilized. Exact size estimates for these animals are difficult to make but it may have grown to be around 3 feet long. Nautiloid Anatomy Internal and External Tissues Nautiloids are cephalopods whose bodies are mostly covered in shells which may be coiled, curved, or straight. Living nautiluses in the family nautilidae have tightly coiled shells and have bodies which occupy the largest outer living chamber. Their heads and many small tentacles come out of the aperture of the shell while a strong and leathery hood covers the upper portion of the head and seals the shell entrance when the animal retreats inside. Unlike squid and octopus arms, these appendages do not have any suckers. They do not have the complex eyes seen in coleoid cephalopods and instead have more simple pinhole eyes. (BELOW) A labeled diagram of the external anatomy of a nautiloid. Older nautiloid groups often had straight shells but by the Cretaceous period, the surviving family Nautilidae tended to only have tightly coiled shells. Family Nautilidae Temporal Range: Triassic period - Present Diet: Scavengers, remains of fish, crustaceans, other invertebrates Genera in the Western Interior Sea: Stenzeloceras, Eutrephoceras, Cymatoceras Nautilidae is the only surviving family of nautiloids and comprises most of the nautiloid genera known from the Late Cretaceous. The shells of these animals form a flat coil and, like the shells of ammonoids, contain chambers separated by walls called septa. The nautilid itself lives in the outermost chamber, whereas the inner chambers hold gas and liquid and are connected to a tube-like siphuncle which adjusts the fluid balance of the shell to help the animal control its buoyancy. Nautiloids were already much less common in the Cretaceous period than they had been in earlier time periods. They may have managed to survive the end-Cretaceous extinction event by taking shelter in deep waters. Lifestyle: Near-benthic, tend to swim near ocean floor (BELOW) The genus Stenzeloceras from the Late Cretaceous, Campanian stage. Found in Alabama. Species in the Western Interior Sea: S. sinuosum (BELOW) The genus Cymatoceras from the Late Jurassic to the Oligocene epoch. Species found in the Western Interior Sea: C. texana. Found in Texas (BELOW) The genus Eutrephoceras from the Early Cretaceous to the Pliocene epoch. Species found in the Western Interior Sea: E. dekayi. Found in Montana, South Dakota, Mississippi, Alabama, Texas, Tennessee Suggested References: Coleoids, Nautiloids Brinster, K. F. (1970).” Molluscan Paleontology of the Pierre Shale (Upper Cretaceous), Bowman County, North Dakota (MS).” University of North Dakota. Everhart, M.J. (2017). “Oceans of Kansas - A Natural History of the Western Interior Sea,” Second Edition. Indiana University Press, 460 pp. Green, R.G. (1977). “Niobrarateuthis walkeri, a new species of teuthid from the Upper Cretaceous Niobrara Formation of Kansas”. Journal of Paleontology 51(5):992-995. Jeletzky, J.A. (1961). “Actinocamax from the Upper Cretaceous Benton and Niobrara Formations of Kansas.” Journal of Paleontology 35(3):505-53 Kauffman, E.G., Sageman, B.B., Kirkland, J.I., Elder, W.P., Harries, P.J. and Villamil, T. (1993). “Molluscan biostratigraphy of the Cretaceous Western Interior Basin, North America”. pp. 397-434 in Caldwell, W.G.E and Kauffman, E.G. (eds.), Evolution of the Western Interior Basin. Kauffman, E.G. (2004). “Mosasaur predation on Upper Cretaceous nautiloids and ammonites from the United States Pacific Coast.” Palaios 19(1):96-100. Larson, N. L; Jorgensen, S.D ; Farrar, R. A. & Larson, P. L. (1997). “Ammonites and the Other Cephalopods of the Pierre Seaway”. Geoscience Press, Inc. p. 44 Selden, P. A., ed. 2009. Treatise on Invertebrate Paleontology. Part L, Mollusca 4, Revised, vol. 2. The University of Kansas Paleontological Institute. Lawrence, Kansas

Explore the different types of rays, skates, chimaeras and guitarfishes who lived during the Cretaceous period in the Western Interior Sea Chimaeras and Batomorphs Rays, Ratfishes and Hybodonts of the Cretaceous Seas The seas of the Cretaceous period were home to many types of cartilaginous fishes besides sharks. These included rays, skates, guitarfishes and chimaeras, all of which had skeletons made up mostly of cartilage rather than bone. Because cartilage rarely fossilizes these animals are typically represented in the fossil record by their teeth, tooth plates, fin spines, and tiny dermal denticles. Just as in today’s oceans many flat-bodied cartilaginous fishes lived in a range of habitats from shallow coastal waters to deeper parts of the seaway. The broad, flattened bodies of Cretaceous rays, skates and guitarfishes were well suited for life on the sea floor where they preyed on shellfish, crustaceans, and other benthic organisms. Chimaeras, often referred to as ghost sharks or ratfishes, formed another distinctive group within this marine ecosystem. These animals are part of a very ancient lineage which has survived to the present day. They have mouths filled with powerful crushing tooth plates and also specialize in feeding on hard-shelled animals. Some extinct groups of cartilaginous fishes could also be found in the waters of the Western Interior Sea who have no direct living descendents. The rajiform order of fishes included the extinct sclerorhynchoidei, a line of fishes who closely resembled today’s sawfishes with their long spiny rostrums despite not being particularly related to living sawfishes or sawsharks. The seas of the Cretaceous period were also home to hybodonts. Although they outwardly would have closely resembled sharks, hybodonts are usually considered to be part of their own separate order which disappeared at the end of the Cretaceous. Anatomy (BELOW) A labeled diagram of the skeleton of an eagle ray, Myliobatis, showing the positions of the various cartilages which support the bodies of these animals in life. Some of the shapes of the ceratotrichia have been simplified for this diagram Skeletal Anatomy Rays and other non-shark cartilaginous fishes have skeletal systems composed primarily of cartilage rather than bone. In rays and guitarfishes, the skeleton supports a flattened body plan, with greatly expanded pectoral fins which are connected to the sides of the head. The skull and jaw apparatuses are supported by specialized arch-shaped cartilaginous structures that also connect to the gills and sensory organs. Stingrays and skates generate most of their forward movement by flapping their pectoral fins whereas animals like guitarfishes and presumably extinct sclerorhynchoid fishes still had small tail flukes which they could use to push themselves forward. Many of these animals have flattened teeth that are very good for crunching down on hard-shelled prey. Some groups even independently developed saw-like rostral organs covered in long tooth-like denticles used to slash at soft-bodied prey animals. Chimaeras have an even more specialized condition. Instead of having separated individual teeth these animals have large, durable tooth plates that grow continuously throughout their lifespans. They also differ from rays and sharks since they have a single external gill opening on each side of the head and an upper jaw that is permanently fused to the rest of the skull. Because cartilage rarely fossilizes, the fossil record of these fishes is mostly composed of durable elements such as teeth, tooth plates, fin spines, vertebral centra, and dermal denticles, although some exceptional fossils do exist which preserve the entire bodies of extinct cartilaginous fishes. Rays, Hybodonts and Batomorphs Stingrays (Order Myliobatiformes) Dasyatis Myliobatis Rhombodus Skates (Order Rajiformes) Ischyrhiza Onchopristis Ptychotrygon Texatrygon Walteraja Chimaeras (Order Chimaeriformes) Edaphodon Ischyodus Hybodonts (Order Hybodontiformes) Lonchidion Meristodonoides Electric rays (Order Torpediniformes) Proplatyrhina Guitarfishes (Rhinopristiformes) Pseudohypolophus Rhinobatos Stingrays (Myliobatiformes) Temporal Range: ~130 million years ago - Present Diet: Some genera are durophagous, others are filter feeders Genera in the Western Interior Sea: Rhombodus, Dasyatis, Brachyrhizodus, Myliobatis The order Myliobatiformes includes stingrays, manta rays, devil rays and eagle rays. These fishes have flattened bodies with large pectoral fins which make up a large portion of the tissues of the sides of their bodies. Many members of this group also have smaller pelvic fins further to the rear of their bodies. These large fins are the main source of forward propulsion for these animals. Many species live on or near the seafloor where they use highly sensitive electroreceptors, known as the ampullae of Lorenzini, to locate prey hidden beneath sand or mud. Others are pelagic animals who live in open water and act as filter feeders who strain through the water in order to capture microscopic plankton. Most myliobatiform fishes have long, narrow tails which sometimes end in venomous barbs used for protection against predators. (ABOVE) The genus Rhombodus from the Late Cretaceous and early Paleogene. Found in North Dakota, South Dakota, New Jersey. Species: R. laevis, R. microdon (BELOW) The genus Dasyatis, a genus of stingrays found from the Cenomanian stage to the present day. Species in the Interior Sea: D. northdakotaensis . Found in North Dakota (BELOW) The genus of cownose ray Brachyrhizodus from the Late Cretaceous. Species in the Western Interior Sea: B. wichitaensis, B. ellipsis. Found in New Jersey, Alabama, Mississippi, Texas, Kansas, South Dakota (BELOW) The genus Myliobatis from the Maastrichtian stage of the Late Cretaceous to the present day. Species in the Western Interior Sea: M. foxhillsensis. Found in North Dakota (BELOW) A pair of Myliobatis eagle ray teeth. These animals became particularly common in the marine fossil record starting in the Paleogene period but their first fossils are found at the very end of the Cretaceous period. Skates (Rajiformes) Temporal Range: ~190 million years ago - Present Diet: Some genera are durophagous, others are soft prey specialists Genera in the Western Interior Sea: Walteraja, Onchopristis, Ptychotrygon, Ischyrhiza, Texatrygon The order Rajiformes includes skates and their extinct relatives the sclerorhynchoids, also known as the sawskates. These animals have different tail anatomies than the long thin tails seen in myliobatiform fishes. Skates instead have sturdy tails that lack venomous stinging barbs. Their tails are sometimes covered in a row of short spines. This feature is taken a step further in the case of the sclerorhynchoids. These extinct fishes who were very common during the middle and Late Cretaceous developed long, flattened snouts lined with rows of tooth-like denticles along their edges, producing a distinctive saw-like appearance. Species such as Onchopristis and Ischyrhiza most likely used their elongated rostra to slash at prey or to search through layers of sediment for hidden animals. Many of these animals also seem to have had several sets of spiny denticles along their backs and on the edges of their pectoral fins. Skates and their closest relatives reproduce by laying soft egg cases known as “mermaid’s purses.” (BELOW) The genus Walteraja from the Late Cretaceous, Maastrichtian stage. Found in North Dakota. Species: W. exigua (BELOW) The genus Onchopristis from the early and Late Cretaceous, Barremian stage - Cenomanian stage. Species found in the Western Interior Sea: O. dunklei. Found in Texas. (BELOW) The genus Ptychotrygon from the early and Late Cretaceous, Albian stage - Maastrichtian stage. Found in Texas, Alabama, North Dakota. Species found in the Western Interior Sea: P. greybullensis, P. winni (BELOW) A Ptychotrygon oral tooth. This particular genus seems to have undergone a process called "depristification" where their rostra do not seem to have had large outward-facing spiny denticles (BELOW) The genus Ischyrhiza from the late Cretaceous, Cenomanian - Maastrichtian stages. Species found in the Western Interior Sea: I. avonicola. Found in Texas, North Dakota, Wyoming, Montana (BELOW) The genus Texatrygon from the Late Cretaceous. Found in Georgia, Alabama, Mississippi, Texas, Utah Species: T. brycensis Chimaeras (Chimaeriformes) Temporal Range: ~350 million years ago - Present Diet: Durophagous, hard-shelled prey Genera in the Western Interior Sea: Ischyodus, Edaphodon The order Chimaeriformes is a group within the larger subclass of cartilaginous fishes called the holocephali. This is a very old group of fishes and the fossil record of their relatives goes back as far as the Devonian period. These fishes have a single external gill opening on each side of their heads which is covered by a fleshy operculum. Most other types of cartilaginous fishes have multiple gill slits behind or below their heads. The upper jaws of chimaeras are usually fused to the rest of their skulls which gives these animals a more solid anchor for their crushing tooth plates. Living chimaeras tend to live deep in the ocean and as a result often have large eyes which allow them to see even in low light conditions. This feature may have been present in extinct North American Cretaceous chimaeras as well since the deepest parts of the Western Interior Sea would have been far enough below the surface that only a limited amount of light would have reached the seafloor. (BELOW) The genus Ischyodus from the Jurassic period to the middle Miocene epoch. Species found in the Western Interior Sea: I. rayhassi. Found in North Dakota. (BELOW) The genus Edaphodon from the Early Cretaceous to the Pliocene epoch. Species found in the Western Interior Sea: E. hesperis. Found in British Columbia Hybodonts (Hybodontiformes) Temporal Range: 360 - 66 million years ago Diet: Carnivorous, soft prey specialists Genera in the Western Interior Sea: Meristodonoides, Lonchidion The order Hybodontiformes is an extinct group of shark-like cartilaginous fishes who persisted through to the end of the Mesozoic but ultimately became extinct at the end of the Cretaceous. Although they are often referred to as sharks, hybodonts do not fall within the division selachii and are therefore not true members of the shark group. These animals had very tall spines on each of their dorsal fins. These spines are often covered in ridges or groove-like markings. These spines probably helped ward off potential attacks from other marine predators. Male hybodonts had two small cephalic spines on their head, a feature thought to have played a role in reproduction although their exact purpose remains unclear. Fossils of different types of hybodonts have been recovered from saltwater, freshwater and brackish environments. (BELOW) The genus Meristodonoides from the Early and Late Cretaceous, Aptian - Maastrichtian stages. Found in New Jersey, Texas, Montana, Wyoming, Minnesota, Mississippi. Species: M. butleri, M. montanensis, M. novojerseyensis, M. rajkovichi, M. multiplicatus (BELOW) The genus Lonchidion from the Triassic to the Late Cretaceous period. Electric Rays (Torpediniformes) Temporal Range: 90 million years ago - Present Diet: Carnivorous, fishes, benthic invertebrates Genera in the Western Interior Sea: Proplatyrhina The order Torpediniformes is the order which contains the living electric rays. These animals are unique for having large electric organs situated on either side of the head which can generate electrical discharges used to stun prey and deter predators. The front parts of the bodies of electric rays are usually oval shaped and formed from a wide pair of pectoral fins. Their bodies are typically thicker and more muscular than those of many other rays and their tails sometimes end in a fluke. These animals often also have a pair of distinct dorsal fins with rounded tips located along the upper surfaces of their tails. Instead of depending on their eyesight, electric rays usually rely on picking up the electrical signals of prey species which they are able to detect even through layers of oceanic substrate on the seafloor. They tend to feed on small benthic vertebrates. (BELOW) The genus Proplatyrhina from the Late Cretaceous period Guitarfishes (Rhinopristiformes) Temporal Range: 150 million years ago - Present Diet: Carnivorous, fishes, invertebrates Genera in the Western Interior Sea: Rhinobatos, Pseudohypolophus The order Rhinopristiformes is the group which contains guitarfishes, sawfishes, and their relatives. The members of this order have long bodies with flattened heads and forebodies, while the rear portion of the body is similar to the rear halves of sharks, ending in a well-developed tail. Most rhinopristiform fishes are benthic predators that use their mouths which are positioned on the ventral surfaces of their bodies to feed on invertebrates and small fishes hiding in the seafloor sediment. Like many types of rays they have electroreceptors that help them to detect prey concealed beneath layers of sand or mud. (BELOW) The genus Rhinobatos from the late Jurassic period - Present. Species found in the Western Interior Sea: R .incertus. Found in Colorado, Kansas, Texas, Montana (BELOW) The genus Pseudohypolophus from the Late Cretaceous. Unclear affinities, some studies recover it as a member of Myliobatiformes. Found in Texas, Utah, Montana, Kansas (BELOW) The genus Myledaphus from the Late Cretaceous, Turonian-Maastrichtian stages. Species found in the Western Interior Sea: M. bipartitus, M. pustulosus. Found across southern and central North America, from Alberta to Alabama Suggested References: Chimaeras, Batomorphs Case, G.R. (1965). “An occurrence of the sawfish, Onchopristis dunklei, in the Upper Cretaceous of Minnesota”. Journal, Minnesota Academy of Science, 32(3):183. Cicimurri, D., (2000). “Cretaceous elasmobranchs of the Greenhorn Formation (Middle Cenomanian-Middle Turonian), western South Dakota”. 6th Fossil Conference Proceedings volume. :27-43. Duffin, C. J., (2001). “A chimaerid (Holocephali, Chimaeriformes) vomerine toothplate from the Upper Cretaceous of Belgium”. Palaeontology, 44(6)1179-1188. Everhart, M.J. (2017). “Oceans of Kansas - A Natural History of the Western Interior Sea, Second Edition”. Indiana University Press, 460 pp. Everhart, M. J. (2005). “New stratigraphic records (Albian-Coniacian) of the guitarfish, Rhinobatos incertus (Chondrichthyes; Rajiformes), from the Cretaceous of central and western Kansas”. Journal of Vertebrate Paleontology, 25(Supplement to 3): 55A. Lucas, Spencer G.; Sullivan, Robert M. (2006). “Late Cretaceous Vertebrates from the Western Interior: Bulletin 35”. New Mexico Museum of Natural History and Science. McNulty, C. L. Jr. and B. H. Slaughter. (1964). “Rostral teeth of Ischyrhiza mira Leidy from northeast Texas.” Texas Jour. Sci. 16:107-112. McNulty, C. L. Jr. and B. H. Slaughter. (1972). “The Cretaceous selachian genus, Ptychotrygon Jaekel 1894”. Eclog. Geol. Helvetiae 65(3):647-656. Shimada, K. (1993). “Upper Cretaceous elasmobranchs from the Blue Hill Shale Member of the Carlile Shale, Western Kansas”. Kansas Academy of Science Abstracts, 12(78). Villalobos-Segura, Eduardo; Underwood, Charlie J.; Ward, David J.; Claeson, Kerin M. (2019). "The first three-dimensional fossils of Cretaceous sclerorhynchid sawfish: Asflapristis cristadentis gen. et sp. nov., and implications for the phylogenetic relations of the Sclerorhynchoidei (Chondrichthyes)". Journal of Systematic Palaeontology. 17 (21): 1847–1870. Welton, B. J., and R. F. Farish (1993). "The Collector's Guide to Fossil Sharks and Rays from the Cretaceous of Texas." Before Time, Lewisville, Texas, 204 pp.

Explore different types of bryozoans, corals, sponges, tusk shells and brachiopods who lived during the Cretaceous period in the Western Interior Sea! Misc. Invertebrates Corals, Bryozoans, Brachiopods, Scaphopods and Sponges In addition to the more common remains of bivalves, cephalopods, gastropods and sea urchins, rare fossils of sponges, stony corals, bryozoans and brachiopods are sometimes recovered from deposits formed by the Western Interior Sea. These animals seem to have fared poorly in the lime-rich mud which coated the floor of the seaway. Notably this ancient body of water preserves no remains of large stony coral-based reef systems like the ones we are used to seeing in today’s tropical seas. Most of the reefs built in this ecosystem were formed by bivalves like rudists or oysters and the corals that we do find in these areas are usually considered solitary corals. Nevertheless many of these types of invertebrates found as fossils formed by the Western Interior Sea are part of genera which still contain extant species. Many of them seem to have changed very little in the intervening years, which indicates that by the Late Cretaceous many of these animals had already moved into niches similar to those occupied by their modern relatives. Brachiopods Temporal Range: ~530 million years ago - Present Diet: Filter feeders: plankton, organic waste Genera in the Western Interior Sea: Terebratulida, Lingula Brachiopods are hard-shelled animals who appear outwardly similar to bivalves, despite being very distantly related to one another. These animals have a soft inner body sealed within two hard valves which are hinged at their base and often supported by a type of fleshy tube called a pedicle. Brachiopods are generally split into two groups based on the form of their hinges into articulate brachiopods and inarticulate brachiopods. Articulate brachiopods like Terebratulida have small tooth-like structures near their hinges and usually have a small opening in their lower valve from which the pedicle can extend. Inarticulate brachiopods like Lingula on the other hand have no tooth structures on their hinges. Their pedicles usually come out from the apex point of their shells. (ABOVE) Brachiopod genera from the Western Interior Sea: (A) Lingula , (B) Terebratulida Bryozoans Temporal Range: ~518 million years ago - Present Diet: Filter feeders: plankton, organic waste Genera in the Western Interior Sea: Membranipora, Pyripora Bryozoans are a group of typically colonial animals whose forms are composed of many small individual organisms called zooids. These zooids are specialized to perform specific functions used to keep the rest of the colony alive. This can include helping to expel waste or catching food. Fossil bryozoans found in rocks from the Western Interior Sea come in a few different shapes, with some resembling fans or pieces of netting while others look like small chains. Many of these Cretaceous bryozoa would attach themselves to rocks or to the soft substrate of the seafloor. (ABOVE) Genera of bryozoans known from the Western Interior Sea, (A) Membranipora , (B) Pyripora Temporal Range: ~340 million years ago - Present Tusk Shells (Scaphopoda) Diet: Detritivore: organic waste, benthic microinvertebrates Genera in the Western Interior Sea: Cadulus, Dentalium Scaphopods are a class of mollusks whose fossil record dates back to the early Carboniferous period. They are an exclusively marine group and their fossils do not appear in depositional environments formed by areas covered in freshwater. These animals spend their lives searching for small pieces of food by sifting through the sediment on the seafloor with their thin hairlike tentacles. Their closest relatives on the mollusk family tree seem to be the cephalopods. Sponges (Porifera) Temporal Range: 544 million years ago - Present Diet: Filter feeders: plankton, organic waste, some genera eat larger prey Genera in the Western Interior Sea: Actinostromaria, Cliona Sponges are some of the oldest groups of animals with their origins possibly going back to even before the start of the Cambrian period. They use a special set of choanocyte cells to circulate water through their bodies and use this process in order to strain most of their food out of the water. Some sponges who live in nutrient poor environments can become carnivorous but most are filter feeders. They tend to be mostly stationary animals although some types of mature sponges are able to move over the seafloor at very slow speeds. Their fossils are fairly rare in deposits from the Western Interior Sea. Most of the sponges found in these Cretaceous rocks are the fossils of burrowing or boring sponges like those in the genus Cliona. (ABOVE) Genera of sponges known from the Western Interior Sea, (A) Actinostromaria, (B) Cliona Stony Corals (Scleractinia) Temporal Range: 240 million years ago - Present Diet: Filter feeders: plankton, organic waste Genera in the Western Interior Sea: Thamnasteria, Astrangia Stony scleractinian corals are some of the primary reef building organisms found in today’s oceans. They are usually colonial animals who form from an original polyp which begins to form the rest of the mass of a larger piece of coral by replicating itself asexually. This process is called budding. As the coral grows the polyps begin to secrete compounds which form into a hard skeletal structure composed of the mineral calcium carbonate. These mineralized skeletons tend to fossilize easily and so the fossil record for stony corals, which began to appear in the middle Triassic, is fairly complete. However, during the Cretaceous period stony corals were replaced as reef builders in some parts of the world by rudist bivalves. Fossils of these stony corals are fairly rare in the Western Interior Sea and are mostly known from deposits left behind by nearshore environments like those of the Woodbine formation in Texas. (ABOVE) Genera of stony corals known from the Western Interior Sea, (A) Thamnasteria (B) Astrangia Suggested References: Misc. Invertebrates Bayer, F. M., et al. (1956). “Systematic Descriptions, in Moore, R. C., eds., Treatise on Invertebrate Paleontology, Part F, Coelenterata, Volume 1.” The University of Kansas and Geological Society of America. F16-F20 pp. Emig, Christian C. (May 2003). "Proof that Lingula (Brachiopoda) is not a living-fossil, and emended diagnoses of the Family Lingulidae". Carnets de Géologie / Notebooks on Geology. CG2003 (L01): 1–8. Hooper, J. (2018). "Structure of Sponges". Queensland Museum. "WoRMS - World Register of Marine Species - Cliona Grant, 1826" Moore, R.C. (1965). Brachiopoda. Treatise on Invertebrate Paleontology. Vol. Part H., Volume 1. Boulder, Colorado/Lawrence, Kansas: Geological Society of America/University of Kansas Press. pp. H263. WoRMS - World Register of Marine Species - Scleractinia".

Explore the different kinds of ray-finned fishes found in the Western Interior Sea, including animals like Xiphactinus, Enchodus and Pachyrhizodus Ray-finned fishes (continued) Ray-Finned Fishes Order Ichthyodectiformes Gillicus Ichthyodectes Prosaurodon Saurocephalus Saurodon Xiphactinus Order Pycnodontiformes Anomoeodus Coelodus Gyrodus Micropycnodon Palaeobalistum Order Semionotiformes Hadrodus Order Crossognathiformes Apsopelix Elopopsis Pachyrhizodus Order Elopiformes Laminospondylus Family Pachycormidae Bonnerichthys Protosphyraena Order Aulopiformes Apateodus Cimolichthys Enchodus Leptecodon Stratodus Order Beryciformes Caproberyx Kansius Order Tselfatiiformes Bananogmius Enischnorhynchus Ferrifrons Luxilites Martinichthys Niobrara Pentanogmius Pseudanogmius Syntegmodus Thryptodus Zanclites Order Polymixiiformes Omosoma Order Albuliformes Paralbula Pollerspoeckia Family Apogonidae Apogonidarum Order Amiiformes Cyclurus Paraliodesmus? Order Anguiliformes Anguilavus Urenchelys Family Ariidae Vorhisia Order Aspidorhynchiformes Belonostomus Family Lepisosteidae Atractosteus Lepisosteus Previous Page Tselfatiiform Fishes Plethodids of the Western Interior Sea Temporal Range: 113 million years ago - 66 million years ago Geographic Range: North America, Africa, Europe Genera in the Western Interior Sea: Pentanogmius, Bananogmius, Thryptodus, Ferrifrons, Zanclites, Niobrara, Martinichthys, Syntegmodus, Luxilites, Pseudanogmius Diet: Carnivorous, small fish, invertebrates Tselfatiiform fishes were an extinct group of marine bony fishes from the Cretaceous period. They are known for their roughly diamond-shaped bodies that were flattened from side to side. These fishes had reinforced head bones and many species had long, tall dorsal fins and small pelvic fins. The Tselfatiiform fishes of the Western Interior Sea were all part of the family Plethodidae. Most of these animals were fairly small fishes, only a few feet long at most, although a few genera are known to have grown to be more than 5 feet long in some parts of the world. The best known plethodids are animals like Bananogmius and Pentanogmius who would have appeared somewhat similar to today’s angelfishes. Some plethodids had their own unique structures found on their skulls. Martinichthys had a long-spine-like projection issuing from the front of its upper jaw while Thryptodus had a reinforced nasal area which has given it the nickname “battering ram fish”. These animals seem to have been either plankton-eating filter feeders or animals who ate smaller fish. (BELOW) Plethodid genera included some genera with long rostral bones and others with very tall dorsal fins. Some genera like Pentanogmius had significant differences between their different species such as P. evolutus and P. fristchi (BELOW) The plethodid genus Enischnorhynchus has an upermost size estimate which might make it quite a bit larger than many of the other types of plethodids found in the Western Interior Sea. (BELOW) A plethodid tooth plate from the Cenomanian of Texas. Fossil collected and original photo taken by Jared Cooke/ jcookepaleo Squirrelfish Relatives Beryciformes Temporal Range: 100 million years ago - Present day Geographic Range: Worldwide distribution Genera in the Western Interior Sea: Kansius, Caproberyx Diet: Carnivorous, small fish, invertebrates Beryciform fishes are an order of ray-finned fishes which contains today’s squirrelfishes, soldierfishes and their closest relatives. They have large eyes, deep bodies, and long spines supporting their dorsal fins. In the Western Interior Sea, beryciform fishes were mainly represented by members of the family Holocentridae, the same family that includes modern squirrelfishes. One of the best-known genera from this region is Kansius , particularly the species Kansius sternbergi , which has been found in Late Cretaceous chalk formations in Kansas. Fossils show that Kansius was a rather small fish, only a few inches long. Most living and extinct beryciforms also had large mouths and rough scales that helped protect them from predators. Their body shape made them quick and agile swimmers in marine environments. The large eyes may have helped them see better in deeper or dimly lit waters. Beardfishes Polymixiiformes Temporal Range: 93 million years ago - Present day Geographic Range: Worldwide distribution Genera in the Western Interior Sea: Omosoma Diet: Carnivorous, small fish, invertebrates Polymixiiformes (Beardfishes) are a type of fish who are named for the long sensory barbels, or whisker-like structures, located beneath their lower jaws. These barbels were used to help detect food in the water or along the seafloor. Beardfishes also have very large eyes used to see in low light conditions. The best represented genus of beardfishes in the Western Interior Sea is Omosoma . It measured only a few inches long and its fossils are sometimes found inside the shells of large inoceramid clams. They seem to have preferred to live near the seafloor, feeding on small benthic animals. Bonefishes Albuliformes Temporal Range: 147 million years ago - Present day Geographic Range: North America Genera in the Western Interior Sea: Paralbula, Pollerspoeckia Diet: Carnivorous, small fish, crustaceans Albuliformes is an order of ray-finned fishes which contains today’s bonefishes. Cretaceous albuliform fishes look fairly similar to their modern relatives and they are mostly found in deposits formed by shallow water environments in Texas and Montana. They would have had long, streamlined bodies and forked tails with rounded tips. Today’s bonefish are carnivorous animals who hunt for small fishes and invertebrates in near-shore shallow water environments close to the surface. It’s likely that their prehistoric relatives would have occupied similar ecological niches. Some extinct albuliform fish like Paralbula are known from rocks formed in freshwater and brackish habitats. Cardinalfish Apogonidae Temporal Range: ~73 million years ago - Present day Geographic Range: Worldwide distribution Genera in the Western Interior Sea: Apogonidarum Diet: Carnivorous, small fish, invertebrates Cardinalfishes are a group of small ray-finned fishes that belong to the family Apogonidae who have large eyes, relatively large mouths, two separate dorsal fins, and surprisingly strong jaws adapted for feeding on small fish and crustaceans. Modern cardinalfishes are commonly found in reef environments, and fossil species like Apogonidarum show many of the same characteristics as their living kin. Bowfins Amiiformes Temporal Range: ~240 million years ago - Present Geographic Range: North America Genera in the Western Interior Sea: Cyclurus, Paraliodesmus? Diet: Carnivorous, small fish, invertebrates Bowfins belong to the order Amiiformes, a very old group of ray-finned fishes that has been around since the Mesozoic era and are still found today living in freshwater habitats. They have slender bodies and a dorsal fin that extends along much of their back. This long fin helps them swim smoothly and make quick movements while searching for food. Bowfins also have strong jaws lined with sharp teeth which allow them to catch and eat a variety of prey animals. In the Western Interior Seaway, bowfin fossils include the remains of animals like Cyclurus , especially the species Cyclurus fragosus . Fossils of Cyclurus show the classic bowfin features but their presence in chalk deposits from the ancient seaway is good evidence that some ancient bowfins were able to live outside the freshwater habitats which are home to all living species of bowfins. Another genus, Paraliodesmus, may also be a type of bowfin and is known from fossils found in parts of Kansas. Eels Anguilliformes Temporal Range: ~95 million years ago - Present day Geographic Range: Worldwide distribution Genera in the Western Interior Sea: Urenchelys , Anguilavus Diet: Carnivorous, small fish Some early eels were present in the Western Interior Seaway, namely two genera, Urenchelys and Anguillavus . Both of these ancient fishes show the classic elongated body shape we are used to seeing in today’s eels. Some of these genera are known from fairly complete body fossils, some of which seem to show that animals like Urenchelys still had fairly large and deeply forked caudal fins, a feature which is not seen in today’s eels. Saltwater Catfishes Ariidae Temporal Range: ~75 million years ago - Present day Geographic Range: Worldwide distribution Genera in the Western Interior Sea: Vorhisia Diet: Carnivorous, small fish, invertebrates Ariid catfishes, commonly known as sea catfishes, are members of the family Ariidae, a group of catfishes named for their tendency to live in marine environments. They are one of the oldest groups of catfishes and they are easy to recognize with their tall pointed dorsal fins and flattened body shapes. In the Western Interior Seaway, ariid catfishes are known from fossils of a genus called Vorhisia . Most evidence for the presence of Vorhisia in this region comes from fossil otoliths, or ear bones, which are found preserved in marine sediments in parts of the Great Plains. False Needlefishes Aspidorhynchidae Temporal Range: 170 million years ago - 66 million years ago Geographic Range: Worldwide distribution Genera in the Western Interior Sea: Belonostomus Diet: Carnivorous, small fish Aspidorhynchiform fishes were an extinct group of ray-finned fishes that lived during the Mesozoic Era whose members are often compared to the living needlefishes, although the two groups do not seem to be particularly closely related to one another. In the Western Interior Seaway, the most common and well-known member of the Aspidorhynchiformes was Belonostomus , a fish with a long, narrow snout and a slender spear-like body. They had very large eye openings, deeply forked tails and a very flexible spinal cord. They seem to have been small predatory fishes adapted for hunting in the sunlit waters near the surface. Gars Lepisosteidae Temporal Range: ~150 million years ago - Present day Geographic Range: North America Genera in the Western Interior Sea: Atractosteus, Lepisosteus Diet: Carnivorous, smaller fish Gars are an ancient group of fishes whose fossil record from the Late Cretaceous is very extensive. This record includes genera like Lepisosteus , a genus which is still around today and includes longnose and shortnose gars. Fossils of gars who seem to share some characteristics in common with the larger Alligator gars (Atractosteu s) are also known from this area but they are not as common as the remains of Lepisosteus . The most common gar fossils are the remains of their distinctive diamond-shaped scales, which form a thick layer of defensive armor around the animal in life. See the rest of our entries about Cretaceous ray-finned fishes by returning to the previous page Previous Page Media Gallery Suggested References: Ray-Finned Fishes Alvarado-Ortega, Jesús; Porras- Múzquiz, Héctor ( 2009). "On the occurrence of Gillicus arcuatus (Cope, 1875) (Pisces, Ichthyodectiformes) in Mexico". Boletín de la Sociedad Geológica Mexicana. 61 (2): 215–224. Bardack, D. (1965). "Anatomy and evolution of chirocentrid fishes". The University of Kansas Paleontological Contributions. 10: 1–88. Bell, G. L., Jr. (1986). “A pycnodont fish from the upper Cretaceous of Alabama”. Journal of Paleontology 60(5):1120-1126, 2 figs. Bice, K. N.; Shimada, K.; Kirkland, J. I. (2013). "Late Cretaceous Marine Fishes from the Upper Greenhorn Limestone in Southeastern Nebraska". Transactions of the Kansas Academy of Science. 116 (1–2): 22–26. Cope, E. D, (1872), “On the families of fishes of the Cretaceous Formation of Kansas”: Proceedings of the American Philosophical Society, v. 12, p. 327-357. Everhart, M. J. (2007). “Remains of a pycnodont fish (Actinopterygii: Pycnodontiformes) in a coprolite; An upper record of Micropycnodon kansasensis in the Smoky Hill Chalk, western Kansas”. Kansas Academy of Science, Transactions 110(1/2): 35-43. Everhart, M. J. (2010). “Bonnerichthys gladius – The largest bony fish and first known planktivore from the Late Cretaceous”. Kansas Academy of Science, Transactions 113(1-2):123-124. Fielitz, C.; Stewart, J. D.; & Wiffen, J. (1999). “Aethocephalichthys hyainarhinos gen. et sp. nov., a new and enigmatic Late Cretaceous actinopterygian from North America and New Zealand”. Mesozoic Fishes 2 – Systematics and Fossil Record, G. Arratia & H.-P. Schultze (eds.): pp. 95-106, 7 figs. Fielitz, Christopher; González-Rodríguez, Katia A. (2010). "A New Species of Enchodus (aulopiformes: Enchodontidae) from the Cretaceous (albian to Cenomanian) of Zimapán, Hidalgo, México". Journal of Vertebrate Paleontology. 30 (5): 1343–1351. Bibcode:2010JVPal..30.1343F. Fielitz C, Shimada K. (1999).”A new species of Bananogmius (Teleostei; Tselfatiformes) from the Upper Cretaceous Carlile Shale of western Kansas”. Journal of Paleontology 73(3): 504-511. Friedman, Matt; Beckett, Hermione T.; Close, Roger A.; Johanson, Zerina (2016). "The English Chalk and London Clay: two remarkable British bony fish Lagerstätten". Geological Society, London, Special Publications. 430 (1): 165–200. Grande, Lance; Bemis, William E. (1998). "A Comprehensive Phylogenetic Study of Amiid Fishes (Amiidae) Based on Comparative Skeletal Anatomy. an Empirical Search for Interconnected Patterns of Natural History". Journal of Vertebrate Paleontology. 18 (sup1): 1–696. Kanarkina, A.; Zverkov, N.; Polyakova, I. (2024). "New evidence of the global distribution of the swordfish-like pachycormid Protosphyraena in the late Early Cretaceous and a review of global records of the genus". Cretaceous Research. 166. Lucas, Spencer G.; Sullivan, Robert M. (2006). “Late Cretaceous Vertebrates from the Western Interior: Bulletin 35”. New Mexico Museum of Natural History and Science. Maisey, J. G., (1996). “Discovering Fossil Fishes”. Henry Holt and Company, New York. McIntosh, A. P.; Shimada, K.; Everhart, M. J. (2016). "Late Cretaceous marine vertebrate fauna from the Fairport Chalk Member of the Carlile Shale in southern Ellis County, Kansas, U.S.A." Transactions of the Kansas Academy of Science. Near, Thomas J.; Thacker, Christine E. (2024). "Phylogenetic Classification of Living and Fossil Ray-Finned Fishes (Actinopterygii)". Bulletin of the Peabody Museum of Natural History. 65 (1): 3–302. Nelson, Luke E.; Murray, Alison M.; Sims, Megan E. (2026). "A new species of Enchodus from the Western Interior Seaway of North America and a taxonomic revision of Enchodus dirus, Leidy, 1857". Journal of Vertebrate Paleontology. Russell, D. A. (1988). “A check list of North American marine Cretaceous vertebrates including freshwater fishes”. Royal Tyrrell Museum Shimada, Kenshu (2016). "A new species of the Late Cretaceous 'sail-finned' bony fish, Pentanogmius (Actinopterygii: Tselfatiiformes), from Texas, USA". Cretaceous Research. 61: 188–198. Shimada, K. and M. J. Everhart. (2004). “Shark-bitten Xiphactinus audax (Teleostei: Ichthyodectiformes) from the Niobrara Chalk (Upper Cretaceous) of Kansas”. The Mosasaur 7, p. 35-39. Shimada, K. (2015). “Body form and paleoecology of the large Late Cretaceous bony fish, Pachyrhizodus caninus”. Cretaceous Research, 52, 286-291. Stewart, A. (1899). “Pachyrhizodus minimus, a new species of fish from the Cretaceous of Kansas”. Kansas University Quarterly, 8(1), 37-38. Taverne, Louis (2001). "Révision du genre Bananogmius (Teleostei, Tselfatiiformes), poisson marin du Crétacé supérieur d'Amérique du Nord et d'Europe". Geodiversitas. 23 (1): 17–40. Vavrek, Matthew J.; Murray, Alison M.; Bell, Phil R. (2016). "Xiphactinus audax Leidy 1870 from the Puskwaskau Formation (Santonian to Campanian) of northwestern Alberta, Canada and the distribution of Xiphactinus in North America". Vertebrate Anatomy Morphology Palaeontology. 1: 89.

Explore the different species of prehistoric bison, muskoxen, deer, pronghorns and peccaries found in the Midwest during the Pleistocene epoch. Artiodactyla Even-Toed Ungulates Artiodactyla, a group also known as the even-toed ungulates, comprises the largest and most diverse living order of hoofed mammals. Members of this group typically hold their weight on their 3rd and 4th toes, unlike the odd-toed ungulates who walk on feet supported by 1, 3 or 5 toes. Artiodactyls include all of today’s sheep, goats, cattle, pigs, muskoxen, antelopes, pronghorns, giraffes, camels, deer and hippos. The group also includes all of today’s whales, dolphins and porpoises, since these aquatic animals descend from land-dwelling hoofed ancestors. During the Pleistocene epoch the Midwest was home to many types of artiodactyls which have since gone extinct, ranging from giant bison who were as big as rhinos to tiny pronghorns who were less than half as large as their living relatives. Anatomy Skeletal Anatomy Artiodactyls, or even-toed ungulates, are named for a key feature of their foot anatomy, where the third and fourth toes bear the majority of the body's weight. These digits are usually capped with keratinous hooves and serve as the main points of contact with the ground. In many species, the remaining digits have become reduced or vestigial and are only present as small nubs along the back of each foot. In some groups of artiodactyls, such as deer and cattle, the metacarpal and metatarsal bones are fused to form a cannon bone in the areas above the front and hind hooves. These bones give their limbs more stability when moving at high speeds. Their limbs are typically long and thin, although there are of course exceptions to this tendency, such as hippos. Most artiodactyls can move very quickly over short to medium distances. The skulls of these animals also show some specialized features and many types of artiodactyls have horns or antlers that help play a role in defense, communication with other members of their species, and/or competition for mates or territory. Their teeth are generally specialized for plant-based diets, with large grinding molars and, in many ruminants, a reduction or complete lack of upper incisors. (BELOW) Features of the skeletal anatomy of the long-snouted peccary Mylohyus. These animals had many of the traits which are commonly found in artiodactyls, including feet supported by hooves on two toes, tall spinous processes on the thoracic vertebrae and a short tail. These peccaries would have also had rather long tusks. (BELOW) In many large artiodactyls such as bison and camels the tall spinous processes behind the shoulder anchor extensive amounts of soft tissue in the form of a dorsal ridge or hump. These are often used to store fat and energy by animals who live in very harsh or strongly seasonal environments Peccaries (Tayassuidae) Peccaries in the Midwest Peccaries are a group of hoofed mammals in the order Artiodactyla (even-toed ungulates). Their closest relatives are pigs. There are three peccary genera alive today found in parts of North and South America: the white-lipped peccary (Tayassu ), the chacoan peccary (Catagonus ) and the collared peccary or javelina (Dicotyles). These extant peccaries are particularly common in semi-arid environments today but during the Pleistocene, several other types of peccaries were found all throughout the Americas, even reaching as far north as Michigan. Long-snouted peccary Mylohyus nasutus Temporal Range: 5 million years ago to approximately 12,000 years ago Geographic Range: Eastern and central North America , Nebraska, Texas, Florida Species: M. nasutus , M. elmorei, M. floridanus, M. fossilis, M. gildleyi Diet: Omnivorous, roots, tubers, leaves, invertebrates, carrion Mylohyus was an extinct genus of peccary found throughout many parts of North America during the Pleistocene. These animals stood slightly taller than today’s peccaries. Their legs were relatively long and their skulls were particularly large for a peccary. Their canine teeth formed a set of sharpened tusks which they could use as defensive weapons or as tools used to dig in search of roots and edible tubers. The spinous processes on the vertebrae near the shoulder were quite long in these animals and would have been held off the ground at a higher position than the pelvis, giving Mylohyus ’s back a distinctive sloped posture. The genus first appears in the fossil record around the start of the Pliocene epoch and quickly spread across a large part of the southern and eastern areas of the North American continent. Knowledge about their social structure is somewhat murky but they seem to have lived in smaller groups than other Pleistocene peccaries like Platygonus. Flat-headed peccary Platygonus compressus Temporal Range: 10.3 million years ago to approximately 11,000 years ago Geographic Range: Found throughout North and South America Species: P. compressus, P. brachirostris, P. chapadmalensis, P. cinctus, P. kraglievichi, P. marplatensis, P. narinoensis, P. oregonensis, P. pearcei, P. pollenae, P. scagliae, P. setiger, P. striatus, P. texanus, P. vetus Diet: Omnivorous, roots, tubers, leaves, invertebrates, carrion Platygonus was the most widespread genus of North American peccaries from the Pleistocene epoch. In terms of its general appearance, it was similar in size and shape to today’s collared peccaries. The name “flat-headed peccary” refers to the shape of the animal’s forehead, which was smooth with no sharp differences in the angles between the slope of the bones of the forehead and the slope of the nasal bones. Relative to their body sizes, Platygonus peccaries had smaller skulls than their contemporaries like Mylohyus . Fossil assemblages of the remains of large groups of Platygonus are often found in caves, suggesting that they may have used these areas as a source of shelter. They also seem to have been very social animals, with perhaps dozens of animals living together in herds. Peccaries in the genus Platygonus were particularly common in eastern North America, but ranged much further south as well, with other species of Platygonus known from fossils found as far away as Argentina. Deer (Cervidae) Horse-Sized Behemoths and Agile Runners Deer are a group of artiodactyls best known for their unique antlers. Unlike the true horns seen in other groups of animals, deer grow a new set of antlers every year and shed them during the fall. The largest type of deer found in North America today is the moose, which spread across the continent during the Pleistocene epoch. Some extinct deer species from the Pleistocene like the Stag-moose Cervalces rivaled today’s largest moose in terms of size, growing to be nearly as large as a draft horse. Other extinct deer genera from the Pleistocene, like the smaller genus Bretzia , more closely resembled today’s white-tailed deer and mule deer, with a smaller body size than today’s moose and elk, narrower snouts and thinner legs. Some of these extinct animals preferred to live in wetland habitats, while others tended to live in forests. Bretzia nebrascensis Temporal Range: 4.9 million years ago to approximately 10,000 years ago Geographic Range: Central North America, Nebraska, South Dakota Species: B. nebrascensis, B pseudalces Diet: Herbivorous, leaves, twigs, soft buds Bretzia is a genus of deer with two recognized species, Bretzia nebrascensis and Bretzia pseudalces . Bretzia pseudalces is known from fossils found in deposits from Washington state and had broad antlers similar to those of moose. Bretzia nebrascensis is known from fossils found in deposits from the Great Plains and had thinner tines on its antlers, more similar to those seen in the living white-tailed deer. The exact relationship between these two species of Bretzia is somewhat unclear and they may in fact be more distinct from one another than previously thought. Bretzia is classified as a member of the subfamily Capriolinae, along with animals like caribou, mule deer, white-tailed deer, Cervalces and moose. They are more closely related to these types of deer than they are to members of the “old world deer” subfamily such as elk. The genus includes some of the oldest types of deer known from the Americas. Bretzia likely had a long thin snout, thin legs and a gracile body plan. Like most of today’s species of deer, the females of this genus are thought to have lacked antlers. Stag-moose Cervalces scotti Temporal Range (C. scotti) : Middle Pleistocene to approximately 11,500 years ago Geographic Range: Genus found in North America, Europe, Asia Species: C. scotti, C. latifrons, C. carnutorum Diet: Herbivorous, leaves, sedges, aquatic plants The Stag moose, Cervalces , was a close relative to today’s moose. The genus Cervalces contains three species, two of which are only found in Eurasia, as well as the species C. scotti , the only species found in North America. Unlike today’s moose whose antlers each form a single palmate frond-like shape, Cervalces scotti had antlers with a flattened lower palmated section and an upper palmate area with sharper tines. The North American population of Cervalces seems to be descended from a group of Eurasian Cervalces , most likely Cervalces latifrons , which moved across the Bering land bridge into Alaska at some point during the Pleistocene. It seems to have preferred living in woodlands enviroments which sustained high level of rainfall, perhaps wading through shallow water in search of aquatic plants, a behavior often seen in today’s moose. Cervalces had a skull with a large nasal opening. In living moose, the rear parts of the nasal openings are positioned further back on their skulls, leaving room for a large fleshy nose which they can seal off when grazing underwater. In Cervalces , the nasal openings are positioned further forward than in moose but further back than in most other types of deer. This suggests that they may have had a less specialized nasal structure than today’s moose. (BELOW) An antler and skull fragment from a Cervalces on display at the KU Natural History Museum. These fossils were found along the Kaw river in eastern Kansas and date back to the late Pleistocene Camels (Camelidae) Giant Camels and Llama Relatives Camels from the family Camelidae form a group of hoofed mammals which includes all living old world camels, llamas, alpacas, vicunas, guanacos and all their closest extinct relatives. Although there are no living camels native to the Midwest, for most of their evolutionary history camels were most abundant in North America, only spreading to other continents within the last few million years. Camels are part of the suborder Tylopoda, named after the padded feet often seen in living camelids. Unlike true ruminant animals who have four stomach chambers, camels only have three-chambered stomachs making them less efficient at digesting tough plant material like grass. Most camels feed on a mixture of grasses and softer leaves. During the Pleistocene epoch, the Midwest was home to a wide variety of camel genera, including some very large animals like the elephant-sized Titanotylopus as well as smaller relatives of today’s South American camelids. Camelops hesternus Temporal Range: 3.2 million years ago to approximately 13,000 years ago Geographic Range: Western North America , Central America Species: C. hesternus Diet: Herbivorous, grasses, twigs, leaves Camelops , also known as the Western Camel or Yesterday’s Camel, was a Pleistocene camel which somewhat resembled today’s dromedary camels. The shape of the spinous processes over the vertebrae along this camel’s back might indicate that it had a low hump similar to those seen in living camels, although the shape and extent of this soft tissue structure has not yet been determined. These animals seem to be closely related to animals like Paracamelus who crossed over into Eurasia and were the direct ancestors of the camels found in parts of Asia and Africa today. Fossils of Camelops are found from southern Canada all the way to Honduras, indicating that these animals once had a very broad geographical range spreading across most of North America. Standing around 7 feet tall, Camelops would have been similar in size to today’s dromedary camels. It is assumed to have had a flexible lip split into two halves like modern camelids, an adaptation which would have allowed it to easily browse for vegetation and to pull leaves off of branches. Fossils showing many sets of Camelops footprints laid down in the same area show us that these camels were animals who preferred to live in herds. Based on the discovery of Camelops remains found in association with stone tools and showing signs of cut marks on their bones, it seems as though these camels were also hunted by humans who had crossed over into the Americas Hemiauchenia macrocephala Temporal Range: 10.3 million years ago to approximately 12,000 years ago Geographic Range: Found in parts of North and South America Species: H. macrocephala, H. minima, H. blancoensis, H. vera, H. paradoxa, H. seymourensis, H. edensis, H. mirim Diet: Herbivorous, grasses, twigs, leaves Hemiauchenia is a genus of camels in the tribe lamini which seems to have been the direct ancestor of today’s South American camelids like llamas and alpacas. The genus first appeared during the Miocene in North America with fossils of these early animals uncovered in Texas, Kansas, Nebraska and Florida as well as parts of Central America. The genus further expanded into South America once the isthmus of Panama joined the Americas around 2-2.5 million years ago. Species like Hemiauchenia paradoxa appear in South America during the middle Pleistocene. Like many other lamine camelids, Hemiauchenia had a long neck habitually held in a posture which would have positioned most of the cervical vertebrae above the shoulder blades. Their torsos were relatively narrow and they would have lacked the tall spinous processes which could have anchored fleshy humps like those seen in dromedary and bactrian camels. Some species of Hemiauchenia had proportionally larger heads than their living relatives. Hemiauchenia was widespread in North America for much of the Pleistocene but disappeared in North America at the very end of the epoch around 12,000 years ago. The descendants of Hemiauchenia paradoxa diversified in South America during the later part of the Pleistocene. Giant Camel Titanotylopus nebraskensis Temporal Range: 10.3 million years ago to approximately 300,000 years ago Geographic Range: Central and western North America, California, Nebraska Species: T. nebraskensis Diet: Herbivorous, grasses, twigs, leaves Titanotylopus was by far the largest camel found in Ice Age North America. Standing as tall as a small elephant, these animals filled ecological roles similar to those occupied by giraffes on other continents. Thanks to their height and their extremely long necks, they were able to browse for leafy vegetation which was off limits to nearly every other type of Ice Age herbivore. Titanotylopus did not survive long enough to reach the end of the Pleistocene epoch. This genus first appeared during the Miocene epoch and lived up until around 300,000 years ago. In its habitat throughout much of what would one day become the Great Plains it would have been one of the largest hoofed mammals around at the time. Like many of today’s camelids, Titanotylopus camels had very long canine teeth which they may have used as defensive weapons when fighting against potential predators and/or against other Titanotylopus in fights over mates, food or territory. Some paleontologists consider the camels once classified as a separate genus, Gigantocamelus , to be part of the genus Titanotylopus , while others consider these to be two separate genera. (BELOW) A skeleton of Titanotylopus on display at the University of Nebraska State Museum of Natural History (BELOW) A Titanotylopus skull on display at the KU Natural History Museum. Note the large size of the canine teeth. These long teeth were used to fight with other camels over territory, food and water. Male dromedary and bactrian camels still have very large canine teeth today. Palaeolama mirifica Temporal Range: 1.9 million years ago to approximately 3,400 years ago Geographic Range: Found throughout North and South America Species: P. aequatorialis, P. brevirostris, P. crassa, P. crequii, P. hoffstetteri, P. leptognata, P. major, P. niedae, P. paradoxa, P. promesolithica, P. reissi, P. weddeli, P. mirifica Diet: Herbivorous, grasses, twigs, leaves Palaeolama , also known as the Stout-Legged Llama, was a lamine camel related to today’s South American camelids as well as the extinct genus Hemiauchenia . Its remains are found in parts of both North and South America. Unlike most of the other hoofed animals included in this section, Palaeolama did not go extinct at the end of the Pleistocene epoch. The most recent remains of these animals seem to be around 4,200 years old. The genus Palaeolama first appeared in Florida during the middle Pleistocene but these animals would soon move to new habitats, eventually reaching far away Chile and Argentina. In terms of their anatomy and proportions they were roughly similar in appearance to today’s llamas, albeit with slightly shorter legs and a larger maximum body size. Their remains are found in areas which would have been open grasslands, forests and mountainous regions. They seem to have fed on a mixture of grasses, sedges, leaves and softer leaf buds. Bison and Muskoxen (Bovidae) Ancient Relatives of Cattle and Goats Bovids are a family of mammals with four-chambered stomachs and cloven hooves which includes today’s cows, goats, sheep, muskoxen and antelopes. These animals first appeared in Eurasia and by the Pleistocene, North American bovids were still fairly recent arrivals on the continent. During the Pleistocene, the bovid family was represented in North America by members of the Bovinae subfamily (Bison, cattle) as well as members of the subfamily Caprinae (Muskoxen, sheep, etc.). Some of these ancient species seem to have been the direct ancestors of species still found in North America today, while others became extinct towards the end of the Pleistocene or the start of the Holocene. One species from the Pleistocene, the Giant Bison, may have been the largest bovid ever to live in North America. Ancient bison Bison antiquus Temporal Range: 60,000 years ago to approximately 10,000 years ago Geographic Range: Found throughout North America Species: B. antiquus, desendents of this species evolved into B. bison Diet: Herbivorous, grasses, twigs, leaves Bison antiquus , also known as the ancient bison, was a large extinct species of bison which is thought to be the ancestor of the western bison and the species of bison found in North America today. Compared with today’s bison, Bison antiquus was considerably larger and had a taller hump over its shoulder. The presence of this hump is determined based on the presence of extremely long spinous processes on vertebrae near the animal’s shoulders. Patterns of wear on their teeth suggest that they were better suited for feeding on a mixture of soft leaves and tough grasses, spending their lives living in mixed forest-grassland habitats, instead of being grassland specialists. Like today’s bison, these animals are presumed to have lived in large herds, offering them protection from animals like saber-toothed cats, pantherines and large canids which are known from fossil evidence of kill sites to have preyed upon ancient bison fairly regularly. Humans also seem to have hunted these bison, as they were still present when the first people arrived in North America. (BELOW) The skull of an ancient bison on display at the KU Natural History Museum. This particular skull was found in a late Pleistocene deposit in north-eastern Kansas. Giant bison Bison latifrons Temporal Range: 120,000 years ago to approximately 13,000 years ago Geographic Range: Found across North America, from Canada to Mexico Species: B. latifrons Diet: Herbivorous, grasses, twigs, leaves Bison latifrons was the largest bison species to appear in North America during the Pleistocene epoch. It is best known for its gigantic horns which could span 7 feet from tip to tip, much larger than the horn spans of today’s bison. The shape of the rest of the body of Bison latifrons remains something of a mystery as most material known from this animal is composed of fragmentary skulls and horns, but if scaled based on other bison species, these animals would have been truly enormous, reaching masses comparable to those of adult white rhinos. Like all North American bison species, Bison latifrons is thought to have descended from a population of steppe bison who crossed over the Bering land bridge into Alaska and from there spread throughout the rest of North America, diversifying as they entered new habitats. There is some evidence to suggest that Bison latifrons may have given rise to Bison antiquus which was the ancestor of today’s American bison. As a side note, animals of the genus “Bison ” are sometimes considered to be part of the same genus as cattle, the genus “Bos ”. This would make the giant bison Bos latifrons but since this group is more commonly known by the genus name “Bison ” we will continue to use this genus name for our entries about prehistoric bison species. (BELOW) A partial skull and horns of a giant bison (top of the image) on display at the KU Natural History Museum. These remains are much larger than the skulls of other bison species visible on the lower row of this display Western bison Bison occidentalis Temporal Range: 13,000 years ago to approximately 1,700 years ago Geographic Range: Found in Alaska and central North America Species: B. occidentalis, possibly intermediate between B. antiquus and B. bison Diet: Herbivorous, grasses, twigs, leaves Bison occidentalis , also known as the western bison is a type of bison which is sometimes considered its own species or alternatively considered to be a subspecies of American bison. These animals managed to survive up until very recently, with the youngest Bison occidentalis remains having been found at a site dated to be less than 2,000 years old. In terms of their appearance, they were roughly similar to today’s American bison, smaller than their possible ancestor, the much larger Bison antiquus . They had medium-sized horns which pointed up and slightly forwards. Fossils of these animals are found far to the north where they likely would have needed very thick fur in order to survive frigid arctic winters. At various times, different authors have suggested these animals to have constituted their own genus, or to have formed a subspecies of either Bison priscus, Bison antiquus or Bison bison. (BELOW) A skull of a western bison on display at the KU Natural History Museum. The skulls of these bison are very similar to those of the living bison subspecies still found in North America today. Woodland muskox Bootherium bombifrons Temporal Range: 780,000 years ago to approximately 12,000 years ago Geographic Range: Found throughout North America Species: B. bombifrons Diet: Herbivorous, grasses, twigs, leaves Bootherium bombifrons , the woodland muskox, was an extinct species of muskox adapted for life in forested habitats. These animals are sometimes called helmeted muskoxen, since their horns are fused together over their foreheads instead of being separated by a deep gap as in living muskoxen. Bootherium remains are found in sites which represent temperate environments, suggesting that these ancient animals preferred to live in dense woodlands instead of the open tundras where their living relatives can be found today. In order to remain comfortable while living in these warmer habitats, they may have been covered in a lighter coat of fur, especially during the summer months. Although muskoxen superficially resemble cows, they are actually part of the subfamily Caprinae, which also includes today’s sheep and goats. The name for the genus of the living muskox, “Ovibos ”, translates to “sheep-cow” because of this resemblance. Like their living kin, the woodland muskox would have had wide feet well adapted for walking over muddy, snowy or otherwise unstable ground. (BELOW) A skeleton of Bootherium on display at the KU Natural History Museum. This is a particularly complete skeleton which was recovered from the Natural Trap Cave system in Wyoming which has yielded the bones of many types of animals from the late Pleistocene epoch. (BELOW) The top of a skull of Bootherium . The horns of these animals were fused together along the top of the animal's skull, unlike the horns of living muskoxen which are separated from one another by a deep groove (BELOW) The skull of a living muskox (Ovibos ) at the KU Museum. Note the unfused area between the horns in this genus Shrub ox Euceratherium collinum Temporal Range: 1.1 million years ago to approximately 13,000 years ago Geographic Range: Genus is found in Asia and North America Species: E. collinum, E. bizzelli Diet: Herbivorous, soft buds, twigs, leaves Euceratherium, the shrub-ox, was a genus of muskox whose remains are found in parts of Central America, the southern and western parts of the US and parts of China. Fossils of Euceratherium have been found as far south as Guatemala, giving it one of the southern-most ranges of any muskox species. The remains in eastern Asia seem to be the oldest remains of Euceratherium and these animals most likely first appeared in Eurasia before later moving over to North America at some point during the middle Pleistocene. Euceratherium seems to have preferred living in hilly areas where these animals would have fed upon leafy vegetation instead of grass. They are thought to have filled an ecological role similar to that of the living takin, another species of caprine bovid found today in parts of the Himalayas. Like other muskox species, Euceratherium had large horns, although their horns tended to curve sharply forwards instead of upwards as is seen in those of living muskoxen and those of the extinct woodland muskox Bootherium . Pronghorns (Antilocapridae) North America's Endemic Ruminants Antilocaprids are a group of hoofed ruminant mammals native to North America. Although they are often called “antelopes” their closest relatives are giraffes and okapis. Many types of prehistoric antilocaprids can be distinguished from one another based on the shapes of their horns. These horns have some features unique to this group. Although they superficially resemble the true horns found in bovids, antilocaprids are able to shed their horns similarly to the way that deer shed their antlers. Extinct antilocaprids, like today’s pronghorns, were typically grassland specialists and fed on a diet primarily composed of grass, although some ancient antilocaprid varieties may have had a greater preference for browsing on leaves. Capromeryx furcifer Temporal Range: 5 million years ago to approximately 11,000 years ago Geographic Range: Found throughout North and South America Species: C. arizonensis, C. furcifer, C. gidleyi, C. mexicanus, C. minor Diet: Herbivorous, grasses, twigs, leaves Capromeryx , also known as the dwarf pronghorn, was the smallest known antilocaprid genus. It lived in North America from the start of the Pliocene to the late Pleistocene epoch, with its fossils having been found from Nebraska to as far south as central Mexico. The smallest species of Capromeryx had estimated adult body weights in the area of around 25 pounds, making them much smaller that today’s pronghorns. The horns of Capromeryx were arranged into four points. Unlike in Stockoceros or Tetrameryx where their horns point in opposite directions, forwards and backwards, in Capromeryx the horn cores seem to be positioned parallel to one another on each side of the skull. In the remains of some individuals the front and rear horns are of roughly equal length while in others the front horns are considerably shorter than the rear horns. In general it seems as though later species of Capromeryx had smaller horns than their relatives in the Pliocene. Stockoceros conklingi Temporal Range: 1.8 million years ago to approximately 12,000 years ago Geographic Range: Southern North America, as far as central Mexico Species: S. conklingi, S. onusrosagris Diet: Herbivorous, grasses, twigs, leaves Stockoceros was a genus of extinct pronghorns whose fossils are found in the southern parts of North America. Their fossils are found as far north as Texas and as far south as central Mexico, with populations also reaching the Pacific coast in parts of California. Stockoceros had two horns on top of its head and each of these horns was split into two halves of roughly equal length and size. The tips of the horn cores from these animals are slightly rounded instead of pointed, but keratin horn extensions may have meant that their horns grew into a different shape in life in some individuals. Stockoceros was initially considered to be part of the genus Tetrameryx , another larger pronghorn found in Pleistocene deposits, however most workers currently consider it to be a valid separate genus. Most remains of Stockoceros represent animals who are slightly smaller than today’s pronghorns but larger than the dwarf pronghorn Capromeryx . Tetrameryx shuleri Temporal Range: 1.8 million years ago to approximately 12,000 years ago Geographic Range: Found throughout western North America Species: T. irvingtonensis, T. knoxensis, T. mooseri, T. shuleri, T. tacubayensis Diet: Herbivorous, grasses, twigs, leaves Tetrameryx is an extinct genus of pronghorns known from fossils found in the southern and western parts of North America. Many species are classified within this genus, distinguished from one another based on subtle differences in the shapes of their horns. In the best represented species, Tetrameryx shuleri , there is a considerable difference between the sizes of the front and rear horns. In this species, a shorter set of anterior horns sits at the front of the skull with two larger horns behind them. These rear horns could extend to lengths of over 2 feet, making them far larger than the horns of living pronghorns. Tetrameryx appears to have been a more heavily built animal than many of its relatives. As with other antilocaprids, the structure of its leg bones are unique, with the lower legs composed of only the cannon bones without any additional lateral toes. The most recent Tetrameryx populations seem to have died out around 12,000 years ago Media Gallery Suggested References: Artiodactyla Baskin, J., R. Walls, and R. Thomas. (2022). “Bison antiquus and B. latifrons from the latest Rancholabrean (latest Pleistocene), Nueces River Valley, South Texas”. New Mexico Museum of Natural History and Science Bulletin 88: 213. Bover, Pere; Llamas, Bastien; Thomson, Vicki A.; Pons, Joan; Cooper, Alan; Mitchell, Kieren J. (2018). "Molecular resolution to a morphological controversy: The case of North American fossil muskoxen Bootherium and Symbos". Dalquest, W. W. (1974). "A New Species of Four-Horned Antilocaprid from Mexico". Journal of Mammalogy. 55 (1): 96–101 Hoganson, JW (2002). "Occurrence of the Giant Ice Age Bison, Bison latifrons, in North Dakota" (PDF). NDGS Newsletter. 29 (2): 1–3. McDonald, J. N., & Lammers, G. E. (2002). “Bison antiquus from Kenora, Ontario, and notes on the evolution of North American Holocene bison”. Smithsonian Contributions to Paleobiology, 93, 83–97. McDonald, H. Gregory; Dyer, David L.; Shane, Linda C. K.; Haskell, Brian J.; Stafford, Jr., Thomas W. (2024). "The Woodland Muskox Bootherium bombifrons (Artiodactyla, Bovidae) from Hebron, Licking County, Ohio, USA and its Paleoecology in the Great Lakes Region". The Ohio Journal of Science. 123 (2): 44–61. McDonald, H. Gregory. (1989) "New Records of the Elk-moose Cervalces scotti from Ohio". American Midland Naturalist 122.2 : 349-356. Richards, R. L.; McDonald, J. N. (1991). "New Records of Harlan's Muskox (Bootherium bombifrons) and an Associated Fauna from the Late Pleistocene of Indiana". Proceedings of the Indiana Academy of Science. 99 (2–4): 211–228. Spencer, Lillian M.; Scott, Eric (2023). "Resource partitioning among late Pleistocene herbivores of Natural Trap Cave, Wyoming". Quaternary International. 647–648: 88–93. Wilson, M.C.; Hills, L.V.; Shapiro, B. (2008). "Late Pleistocene northward-dispersing Bison antiquus from the Bighill Creek Formation, Gallelli Gravel Pit, Alberta, Canada, and the fate of Bison occidentalis". Canadian Journal of Earth Sciences. 45 (7): 827–859. Zver, Lars; Toškan, Borut; Bužan, Elena (2021). "Phylogeny of Late Pleistocene and Holocene Bison species in Europe and North America". Quaternary International. 595: 30–38.

Explore the different types of prehistoric horses and tapirs found in the Midwest during the Pleistocene epoch Perissodactyla Tapirs, Horses, Rhinos and their Relatives During the Pleistocene epoch, North America was home to several kinds of perissodactyls, also known as odd-toed hoofed mammals. The most abundant were horses of the genus Equus , which occupied a wide range of grassland and open habitats. Several Equus species were found across the continent, and three-toed horses were also found in this region at the start of the Pleistocene. Tapirs could also be found in the Midwest, primarily in wooded regions and hilly areas. Earlier rhinoceros relatives had once inhabited North America during the Neogene period but they were already extinct on the continent by the start of the Pleistocene. Anatomy (BELOW) A labeled diagram of the skeletal anatomy of the Miocene three-toed horse genus Merychippus. Drawing is based on a mounted skeleton at the University of Nebraska State Museum of Natural History Skeletal Anatomy Perissodactyls tend to walk on feet with either one, three or five toes. This is a result of a feature of their skeletal anatomy called mesaxony, a condition in which the body's weight is concentrated on the enlarged third digit of each limb. One-toed horses exhibit the most specialized derived form of this arrangement with only a single functional toe per foot, whereas tapirs and rhinoceroses retain several toes that help provide extra stability when walking over soft ground and distributing their body weights. The gradual loss of toes in horses seems to be an adaptation for running quickly over open grassland habitats. In highly cursorial species certain limb bones have become reduced or partially fused and, like many types of artiodactyls, horses have cannon bones in the areas of their legs just above their feet. The skulls of perissodactyls tend to be fairly elongated with expanded nasal regions. In rhinoceroses, the nasal bones are extra thick in order to support the attachment of their characteristic horns, while in tapirs the nasal openings have become retroverted in order to make space for a short trunk. Some ancient horse genera had a set of deep fossae along the edges of their snouts in front of their orbits which may have held scent glands in life. These fossae are not present in living horse species. The teeth of perissodactyls are specialized for herbivorous diets, with broad grinding surfaces and, in many lineages, high-crowned molars adapted for processing abrasive vegetation. (BELOW) The skull of the extinct horse genus Pliohippus features a series of deep fossae along the sides of its muzzle. These fossae are present in the remains of many types of extinct horses but are absent in the living genus Equus (ABOVE) The skull of a tapir. These animals have particularly heavily built incisors at the front of their jaws and a distinctive retroverted nasal opening which anchors the base of the tapir's trunk External Anatomy Perissodactyls share a number of common physical traits. Their heads are usually rather long and equipped with laterally positioned eyes. Having their eyes on the sides of their heads gives these animals a wider field of view with a larger amount of peripheral vision. Their ears are often tall, rigid and highly mobile and they are able to turn their ears in order to better pick up a sound coming from a particular direction. In some groups, namely tapirs, the front of the skull is equipped with a short, flexible snout used to grasp vegetation, while rhinoceroses have specialized muscles in their upper lips which they use to pull leaves off of branches. Some early horses who fed on leaves may have had similar types of browsing-adapted lips. Body coverings vary a lot between different types of perissodactyls. Horses typically have a coat of hair which can be thin or very thick depending on the local climate, whereas rhinoceroses are covered in thick, protective skin with relatively little hair. Some living tapir species who live at high elevations today have fairly thick coats of fur, which would be what we might expect to see in midwestern ice age tapirs. (BELOW) Features of the external anatomy of a horse (BELOW) Features of the external anatomy of a tapir Horses (Equidae) One-toed and three-toed horses During the Pleistocene, the grasslands and open habitats of the Midwest supported several types of prehistoric horses. The most common were members of the genus Equus , including stout-legged horses such as Equus scotti, a widespread species found across parts of the Great Plains and central North America. Fossil evidence shows that these horses were grazing animals adapted to open environments, much like the wild horse and zebra populations still found around the world today. The region may also have been inhabited by more slender-limbed, “stilt-legged” horses such as Haringtonhippus , which lived alongside Equus species throughout much of North America. Relatives of older horse groups with extra hooves bracing the sides of their main toes could still be found in this area during the early Pleistocene. Equus Temporal Range: 5.3 million years ago to present (outside the Americas) Geographic Range: Genus found on all continents Midwestern species in the Pleistocene: E. scotti, E. simplicidens Diet: Herbivorous grazer, grasses During the Pleistocene, the Midwest was inhabited by multiple species of Equus , the genus that includes modern horses, donkeys and zebras. One of the best-known was Equus scott i, a medium-sized, stout-legged grazing horse that lived in grasslands, open woodlands, and wetlands across much of North America, including parts of the Great Plains and Midwest. Another species, Equus simplicidens, could also be found in this region. This animal, sometimes called a Hagerman horse, had skeletal features similar to those found in today’s zebras. Our knowledge about the coat colors of extinct horses is somewhat limited. Cave art from Eurasia suggests that many Pleistocene wild horses might have appeared very similar to today’s Przewalski's horse, with tan fur and a white muzzle. It may be reasonable to assume that North American species of Equus could have had similar coat colors. (BELOW) A skull from a modern horse on display at the KU Natural History Museum. This particular skull has been cut away to reveal the shapes of the roots of each tooth. Note that some of the rear teeth had not yet fully emerged in this animal. Stilt-legged horse Haringtonhippus francisci Temporal Range: 3 million years ago to approximately 11,000 years ago Geographic Range: Genus across North America from Alaska to Mexico Species: H. francisci, H. achates, H. quinni, H. cedralensis Diet: Herbivorous grazer, grasses Haringtonhippus was an extinct genus of horse that lived in North America during the Pleistocene. The best-known and only recognized species is Haringtonhippus francisci . This animal is often called a “stilt-legged horse” because of its unusually long and slender lower limb bones, which distinguished it from the more heavily built horses of the genus Equus which would have lived alongside it. Fossils of Haringtonhippus have been discovered across a wide geographic range, from Mexico through the western and central parts of North America and into Canada. For many years, these animals were classified within the genus Equus, but genetic analyses of their bones and anatomical studies of their skeletal features later showed that they formed part of a distinct evolutionary lineage. Research indicates that Haringtonhippus was more closely related to modern horses than to the South American genus Hippidion , yet it remained separate from the lineage that includes all of today’s living horses and zebras. Dwarf three-toed horse Nannippus lenticularis Temporal Range: 3.3 million years ago to 1.8 million years ago Geographic Range: Found throughout North America Species: N. lenticularis, N. minor, N. morgani, N. westoni, N. penninsulatus Nannippus lenticularis was a small species of three-toed horse that lived in North America from the late Miocene to the start of the Pleistocene epoch. It belonged to an older group of horses that had been widespread across the continent before the evolution of the larger, one-toed horses such as those of the genus Equus . Fossils of Nannippus have been discovered in Kansas, Nebraska, Alabama, North Carolina, Texas, and Alberta, indicating that it was well adapted to a variety of environments. Unlike modern horses, Nannippus lenticularis retained three functional toes on each foot. The enlarged middle toe bore most of the animal's weight, while the two smaller side toes were positioned higher up and braced the middle toe from each side. Members of the genus Nannippus were relatively small, growing to be around the size of a sheep or a large dog. Dental evidence suggests that Nannippus species were primarily browsers who fed on leaves, shrubs, and other softer vegetation rather than relying exclusively on grasses like today’s horses. This diet allowed them to thrive in woodland and savannah habitats found across North America during the late Miocene, although as grasslands began to spread they faced increased competition from other horses who had become specialist grazers. Diet: Herbivorous browser, leaves, twigs, leaf buds Tapirs (Tapiridae) Ancient tapirs in the Midwest During the Pleistocene, tapirs lived much further north than they do now, with some making their homes in the Midwest. These large herbivores inhabited forests, wetlands, and river valleys, where they fed on leaves, fruits, aquatic plants and other vegetation. Like modern tapirs, they possessed a short, flexible snout that was useful for grasping and manipulating plant material. Although they fall within the “Odd toed” ungulate group, tapirs actually have four main toes on their front feet. Their hind feet have five toes, each of which is tipped in its own hoof-like nail. Tapirus veroensis Temporal Range: 300,000 years ago to approximately 11,000 years ago Geographic Range: Eastern North America Subspecies: T. veroensis Diet: Herbivorous browser, leaves Tapirus veroensis was a species of tapir that lived in eastern North America during the Pleistocene. Fossils attributed to this species have been discovered in Florida, Georgia, Kansas, Missouri, and Tennessee. Although complete details of its external appearance are not known, Tapirus veroensis was likely similar in overall form to living mountain tapirs. We know that these animals had large trunk-like snouts based on the shapes of their nasal openings. The skulls of tapirs have nasal bones which are positioned further back, leaving more space for the soft tissues needed to support a flexible trunk. Although Tapirus veroensis is one of the last types of tapirs to be found in the Midwest, their history in this region goes back millions of years, with the first fossils of ancient tapirs in the Great Plains going back to the Oligocene epoch. Media Gallery Suggested References: Perissodactyla Cirilli, Omar; Machado, Helena; Arroyo-Cabrales, Joaquin; Barrón-Ortiz, Christina I.; Davis, Edward; Jass, Christopher N.; Jukar, Advait M.; Landry, Zoe; Marín-Leyva, Alejandro H.; Pandolfi, Luca; Pushkina, Diana; Rook, Lorenzo; Saarinen, Juha; Scott, Eric; Semprebon, Gina (2022). "Evolution of the Family Equidae, Subfamily Equinae, in North, Central and South America, Eurasia and Africa during the Plio-Pleistocene". Biology. 11 (9): 1258. Eric Scott (2006) “Extinct horses and their relatives, Fossil Treasures of the Anza-Borrego Desert: the Last Seven Million Years”, Sunbelt Publications, p. 253-271 Holanda, E.C.; Ferrero, B.S. (2012). "Reappraisal of the Genus Tapirus (Perissodactyla, Tapiridae): Systematics and Phylogenetic Affinities of the South American Tapirs". Journal of Mammalian Evolution. 20: 33–44. doi:10.1007/s10914-012-9196-z. hdl:11336/18792. S2CID 254697945. Hulbert, Richard C. (2010). "A new early Pleistocene tapir (Mammalia: Perissodactyla) from Florida, with a review of Blancan tapirs from the state" (PDF). Bulletin of the Florida Museum of Natural History. 49 (3): 67–126. Hulbert, Richard C. (1993). "Late Miocene Nannippus (Mammalia: Perissodactyla) from Florida, with a Description of the Smallest Hipparionine Horse". Journal of Vertebrate Paleontology . 13 (3): 350–366. MacFadden, Bruce J (1984). "Systematics and phylogeny of Hipparion, Neohipparion, Nannippus, and Cormohipparion (Mammalia, Equidae) from the Miocene and Pliocene of the New World". Bulletin of the AMNH. 179. Spencer, Lillian M.; Scott, Eric (2023). "Resource partitioning among late Pleistocene herbivores of Natural Trap Cave, Wyoming". Quaternary International. 647–648: 88–93. Vershinina, Alisa O.; Heintzman, Peter D.; Froese, Duane G.; Zazula, Grant; Cassatt-Johnstone, Molly; Dalén, Love; Der Sarkissian, Clio; Dunn, Shelby G.; Ermini, Luca; Gamba, Cristina; Groves, Pamela; Kapp, Joshua D.; Mann, Daniel H.; Seguin-Orlando, Andaine; Southon, John (2021). "Ancient horse genomes reveal the timing and extent of dispersals across the Bering Land Bridge". Molecular Ecology. 30 (23): 6144–6161. Weinstock, Jaco; Willerslev, Eske; Sher, Andrei; Tong, Wenfei; Ho, Simon Y.W; Rubenstein, Dan; Storer, John; et al. (2005). "Evolution, Systematics, and Phylogeography of Pleistocene Horses in the New World: A Molecular Perspective". PLOS Biology. 3 (8): e241.

Explore the different types of giant sloths and armadillos who lived in the Midwest region during the Pleistocene epoch, including animals like Megalonyx and Glyptotherium Xenarthra Sloths, Armadillos and Anteaters Xenarthra is a superorder of animals that originated in South America and includes anteaters, sloths and armadillos. During the Pleistocene Epoch, the Midwest was home to several types of xenarthrans. The most widespread varieties of these ancient animals were the giant ground sloths, huge extinct relatives of today’s tree sloths, some of which could weigh as much as a grizzly bear. In addition to these sloths, the Midwest was also home to different types of armadillos, including glyptodonts, giant plant-eaters protected by thick bony armor, as well as large pampatheres and relatives of the living nine-banded armadillos. These animals spread into North America from South America as part of the Great American Biotic Interchange after the two continents became joined by the Isthmus of Panama. Over time, unique lineages of xenarthrans began to evolve in their new homes, becoming new endemic species only found in certain parts of North America. Anatomy (BELOW) A labeled diagram of the skeletal anatomy of the ground sloth Northrotheriops . Drawing is based on a skeletal mount on display at the KU Natural History Museum. Skeletal Anatomy Xenarthrans are a group of animals whose earliest members were adapted for digging burrows. As a result, many features of their skeletons are connected to their fossorial past. One common feature seen in the skeletons of xenarthrans is the presence of specialized articulation points between the lumbar vertebrae which are sometimes called xenarthrous joints. These extra connections add extra strength to the spine during activities which put a lot of strain on this part of the body such as digging or climbing. In most xenarthrans the forelimbs of these animals are heavily built and their arm bones are covered in enlarged surfaces for muscle attachments. This allows these animals to impart a lot of force from their arms and hands when digging nests or reaching up into trees to grab ahold of leafy branches. In armadillos, the underlying skeleton supports a protective covering of bony dermal plates which together make up the animal’s shell segments. The teeth of xenarthrans can vary a lot as well. Megalonyx, for instance, has a set of four large incisors at the front of its mouth which is a feature not seen in most other types of sloths. Anteaters have no teeth at all and armadillos have somewhat pointed peg-shaped teeth. (BELOW) A labeled diagram showing the key bones and features of the skeletal anatomy of a nine-banded armadillo. For the purposes of this diagram the dorsal shell and cephalic shield are shown only in profile view as a cross-section Shell Anatomy Armadillos are a group defined by their shells. These keratinous plates are a form of body covering that serves as a line of defense against predators and environmental hazards. The shells of armadillos are made of hundreds of small bony plates called osteoderms, which are embedded within the skin and coated by a durable layer of keratin. This armor is organized into distinct sections, usually a set of rigid shields, one over the shoulder and the other over the pelvic region, connected by a series of flexible bands that run across the back. In some glyptodonts the bands along the middle of the shell are absent and the dorsal armor instead forms a single large dome covering the animal's entire back. The tails of armadillos are surrounded by a set of overlapping ring-shaped bands. Some giant South American armadillos like Doedicoerus had bony clubs at the ends of their tails which they could swing around when they felt threatened. An armadillo’s armor is completely attached to the animal's body and is supported by the underlying skeleton. In addition to helping to deter attacks from predators. (BELOW) The plates composing the shell of a nine-banded armadillo. The number of plates in between the pelvic and pectoral shield can vary a lot between genera and some armadillos lack these bands altogether Sloths (Folivora) Ancient giants with huge claws During the Pleistocene Epoch, North America was home to several species of giant ground sloths. Much like their tree-dwelling relatives, the giant ground sloths of the past had long claws on their hands and feet. These claws were used to pull leafy branches down from trees so that they were easier to reach, and possibly as defensive tools to ward off potential predators. The largest sloths of the Pleistocene, animals like the elephant-sized Megatherium and Eremotherium , did not make it far enough to the north to reach the Midwest, but even the relatively mid-sized sloths from this region like Megalonyx and Paramylodon could easily end up weighing half a ton or more. Jefferson's Ground Sloth Megalonyx jeffersonii Temporal Range: 5 million years ago to approximately 13,000 years ago Geographic Range: Found across North America, Alaska to Mexico Species: M. jeffersonii, M. leptostomus, M. matthisi, M. obtusidens, M. wheatleyi Diet: Herbivorous browser, leaves, twigs, buds Megalonyx , commonly known as Jefferson’s ground sloth, was an extinct ground sloth that lived in North America from the Pliocene epoch to the end of the Pleistocene epoch. It was one of the continent’s largest herbivores, reaching about 3 meters (10 feet) in length and weighing up to nearly 1,300 kilograms (2,900 pounds). Its most distinctive features were its powerful limbs and large curved claws, which it likely used to pull down branches and gather vegetation. Fossils of Megalonyx have been found across much of the United States and even as far north as Alaska during warmer periods, making it the most widely distributed North American ground sloth. Megalonyx is also unique in terms of the anatomy of its hind feet. In most ground sloths, the feet are positioned sideways such that the weight of the animal is supported by the sides of their feet, while the soles face towards one another. Megalonyx seems to have retained plantigrade feet, where the sole is placed on the ground. (BELOW) A cranium of the ground sloth Megalonyx on display at the KU Museum. These ground sloths had particularly unique enlarged tusk-like incisors on their upper and lower jaws used to take bites of leafy vegetation Nothrotheriops texanus Temporal Range: 2.5 million years ago to approximately 10,000 years ago Geographic Range: Found in the southern parts of North America Species: N. shastensis, N. texanus Diet: Herbivorous, grasses, fruits, roots, tubers, twigs, leaves Nothrotheriops was one of the most distinctive ground sloths of Ice Age North America. It was relatively small, about the size of a black bear, with a long, slender skull and a narrow mouth. Its powerful forelimbs carried large curved claws used to pull down branches, forage for food, and defend against predators. It had a narrower torso and a longer tail than those seen in most other North American ground sloths, giving it a more slender frame. The species commonly referred to as the “Shasta ground sloth” is Nothrotheriops shastensis , mostly known from the southwestern US. Another species, Nothrotheriops texanus , was found in parts of the southern Great Plains in Oklahoma and Texas. One of the most remarkable features of Nothrotheriops is the exceptional preservation of its soft tissues and integumentary remains. In dry caves of the American southwest, scientists have discovered not only bones but also preserved hair, skin, tendons, and even dung from these animals, providing rare insights into their appearances and diets. These finds show that it fed on a variety of desert plants, including yucca, cacti, and Joshua tree fruits. (BELOW) A Nothrotheriops skull from a mounted skeleton on display at the KU Natural History Museum. Note the shape of the cheekbones. The long lower flange of bone seen in this skull is a feature found in the skulls of many types of ground sloths. Paramylodon harlani Temporal Range: 4.9 million years ago to approximately 12,000 years ago Geographic Range: Found throughout North America as far south as Guatemala Species: P. harlani Diet: Herbivorous, grasses, twigs, leaves Paramylodon was one of the largest ground sloths found in North America. It seems to have been a close relative of the South American sloth genus Glossotherium and its name means “near-Mylodon” , referring to its shared skeletal features with other mylodontid ground sloths. Like other mylodontids, Paramylodon had a long snout with well-developed chewing teeth at the back of its mouth and smaller somewhat sharpened teeth further forward. It is well represented in the tar pits at Rancho La Brea, with the remains of over 70 individual sloths known from this site alone. Mylodontids are suggested to have been better equipped for feeding on grasses than some of their contemporaries like Megalonyx , possibly also using their long claws to dig through the soil in search of roots or tubers. Footprint trackways from New Mexico at White Sand National Monument preserve tracks of a Paramylodon which overlapped with human footprints, possibly left behind by people following the sloth as it moved through the area. Armadillos (Cingulata) Armored hulks and flexible burrowers During the Pleistocene, North America was home to several extinct types of armadillos, including giant glyptodonts and pampatheres. These animals were relatives of modern armadillos but were far larger and more heavily built. Glyptodonts, such as Glyptotherium, were protected by a massive dome-shaped shell made of fused bony plates that covered nearly their entire body. Some species from South America also had heavily armored tails that could be used for defense. Pampatheres like Holmesina were smaller than glyptodonts with their armor formed into more flexible bands instead of rigid domes. Additionally, slightly larger relatives of today’s nine-banded armadillos were also found in the Midwest. Beautiful armadillo Dasypus bellus Temporal Range: 1.8 million years ago to approximately 12,000 years ago Geographic Range: Found across North America Species: D. bellus Diet: Omnivorous, insects, lizards, amphibians, tubers, roots Dasypus bellus , also known as the beautiful armadillo, was a larger relative of today’s nine banded armadillo, both falling within the genus Dasypus . Their shells were arranged with two large half-dome shaped plates, one behind their heads and one in front of their tails. In between these larger pieces of armor they had a set of bony rings which added a degree of flexibility to their shells. Like their modern relatives the tops of their skulls were covered in a thick layer of reinforced shell material, and the underside of Dasypus bellus was not covered in armor. Their tails were long and thin, surrounded by overlapping bony rings. Their feet were tipped with long claws, used for digging in the process of excavating their burrows and they had long thin snouts and peg-like teeth suggesting that they fed on small animal prey such as insects, mollusks and small vertebrates, as well as a small amount of plant matter. This sort of diet is also seen in the living members of their genus. Glyptotherium texanum Temporal Range: 3.9 million years ago to approximately 15,000 years ago Geographic Range: Found in parts of North and South America Species: G. texanum, G. cylindricum Diet: Herbivorous, grasses, twigs, leaves Glyptotherium was a glyptodont and was one of the largest armadillos ever to live in North America. Like all armadillos, glyptodonts were originally a South American group. The majority of their species diversity remained in the southern hemisphere even during the Pleistocene, but some intrepid populations of these animals managed to reach the southern parts of what would one day become the US. Glyptotherium was found much further north than many of its relatives with its fossils being found in parts of Texas, Oklahoma and Florida. It seems to have preferred living in warmer climates and its spread further north may have been limited by lower winter temperatures. The dome-like shell of Glyptotherium was composed of a huge number of small bony plates called osteoderms. These osteoderms displayed a characteristic rosette pattern with a central raised area surrounded by smaller peripheral elements. Their tails did not end in a tail club like those of some of their South American relatives but were instead surrounded by a series of 8-9 rings of armor which were further covered in short spines. Holmesina septentrionalis Temporal Range: 5 million years ago to approximately 12,000 years ago Geographic Range: Genus found in North and South America Species: H. septentrionalis, H. floridanus, H. major, H. occidentalis Diet: Omnivorous, grasses, twigs, leaves, some invertebrates Holmesina was a genus of pampathere, a type of large extinct armadillo who could grow to be around the same size as the living giant armadillo, with maximum lengths of around 6 feet. Their shells were divided into smaller plates instead of forming large rigid domes of armor like those seen in glyptodonts. Most pampatheres remained in South America where their fossil record is the most extensive, but animals like Holmesina were able to cross into North America where they became very successful in the Great Plains and the southern parts of what is now the US. Based on their teeth they are thought to have had a greater preference for plant matter as part of their diet than living omnivorous or insectivorous armadillos. Most of their teeth are fairly flat with broad chewing surfaces which were well developed for processing leaves or grass, unlike the peg-shaped teeth seen in nine-banded armadillos. Media Gallery Suggested References: Xenarthra De Iuliis, Gerardo; Bargo, María S.; Vizcaíno, Sergio F. (2001). "Variation in skull morphology and mastication in the fossil giant armadillos Pampatherium spp. and allied genera (Mammalia: Xenarthra: Pampatheriidae), with comments on their systematics and distribution". Journal of Vertebrate Paleontology. 20 (4): 743–754. Delsuc, F.; Gibb, G.C.; Kuch, M.; Billet, G.; Hautier, L.; Southon, J.; Rouillard, J.-M.; Fernicola, J.C.; Vizcaíno, S.F.; MacPhee, R.D.E.; Poinar, H.N. (2016). "The phylogenetic affinities of the extinct glyptodonts". Current Biology. 26 (4): R155–R156. Fari a, R. A., & Vizcaíno, S. F. (1997). “Allometry of the bones of living and extinct armadillos (Xenarthra, Dasypoda).” Zeitschrift fur Saugetierkunde, 62, 65-70. Gillette, David D.; Carranza-Castañeda, Óscar; White, Richard S.; Morgan, Gary S.; Thrasher, Larry C.; McCord, Robert; McCullough, Gavin (2016). "Ontogeny and Sexual Dimorphism of Glyptotherium texanum (Xenarthra, Cingulata) from the Pliocene and Pleistocene (Blancan and Irvingtonian NALMA) of Arizona, New Mexico, and Mexico". Journal of Mammalian Evolution. 23 (2): 133–154. McDonald, H.G. (2022). "Paleoecology of the extinct Shasta ground sloth, Nothrotheriops shastensis, (Xenarthra, Nothrotheriidae): The physical environment". New Mexico Museum of Natural History and Science Bulletin. 88: 33–43. Naples, Virginia L. (1987), “Reconstruction of Cranial Morphology and Analysis of Function in the Pleistocene Ground Sloth Nothrotheriops shastense (Mammalia, Megatheriidae)”, Contributions in Science 389, October 1987, Natural History Museum of Los Angeles County Schubert, Blaine W.; Graham, Russell Wm.; McDonald, H. Gregory; Grimm, Eric C.; Stafford, Thomas W. (2004). "Latest Pleistocene paleoecology of Jefferson's ground sloth ( Megalonyx jeffersonii ) and elk-moose ( Cervalces scotti ) in northern Illinois". Quaternary Research. 61 (2): 231–240. Scillato-Yané, G. J.; Carlini, A. A.; Tonni, E. P.; Noriega, J. I. (2005). "Paleobiogeography of the late Pleistocene pampatheres of South America". Journal of South American Earth Sciences. Quaternary Paleontology and biostratigraphy of southern South Africa. 20 (1): 131–138. Semken, Holmes A.; McDonald, H. Gregory; Graham, Russell W.; Adrain, Tiffany; Artz, Joe Alan; Baker, Richard G.; Bryk, Alexander B.; Brenzel, David J.; Arthur Bettis, E.; Clack, Andrew A.; Grimm, Brittany L.; Haj, Adel; Horgen, Sarah E.; Mahoney, Meghann C.; Ray, Harold A. (2022). "Paleobiology of Jefferson's Ground Sloth ( Megalonyx jeffersonii ) derived from three contemporaneous, ontogenetically distinct individuals recovered from Southwestern Iowa, U.S.A." Journal of Vertebrate Paleontology. 42 (1) e2124115. Shockey, B. J. (2001). “Specialized knee joints in some extinct, endemic, South American herbivores”. Acta Palaeontologica Polonica, 46(2). Slaughter, B.H. (1959). "The First Noted Occurrence of Dasypus bellus in Texas". Field and Laboratory. 27 (2): 77–80. Web of Science. Stinnesbeck, Sarah (2020). "Mexican fossil ground sloths - A case study for Late Pleistocene megafaunal turnover in the Mexican Corridor". Hochschulschrift. 14: 29. Tomak, C.H. (1982). "Dasypus bellus and Other Extinct Mammals From the Prairie-Creek Site". Journal of Mammalogy. 63 (1): 158–160. doi:10.2307/1380686. JSTOR 1380686. Web of Science. Vizcaíno, S. F.; De Iuliis, G.; Bargo, M. S. (1998). "Skull Shape, Masticatory Apparatus, and Diet of Vassallia and Holmesina (Mammalia: Xenarthra: Pampatheriidae): When Anatomy Constrains Destiny". Journal of Mammalian Evolution. 5 (4): 291–322.