Compared to what we're used to in modern mammals, it also seems that mesonychids would have looked big-headed and also long-necked. spy wednesday images pitt law grade distribution mesonychids limbs and tail. Geisler, J. H. 2001. What springs to mind when you think of a whale? New York: Fowler & Wells. The bones were so numerous that in some fields they were destroyed because they interfered with cultivating the land. Many species are suspected of being fish-eaters, though some of these reconstructions may be influenced by earlier theories that the group was ancestral to cetaceans. Huxley replied that there could be little doubt thatBasilosaurusprovided clues as to the ancestry of whales. Comments: Together, these traits suggest that Pakicetus represents an early stage in the evolution of cetaceans, one where many running adaptations were retained but rarely used. Mammals diversified in the shadow of the great archosaurs, and they remained fairly small and secretive until the non-avian dinosaurs were wiped out by a mass extinction 65 million years ago. But while preparing the sixth edition, he decided to include a small note aboutBasilosaurus. 2001. Some mesonychids are reconstructed as predatory (comparable to canids), others as scavengers or carnivore-scavengers with bone-crushing adaptations to their teeth (comparable to the large hyenas), and some as omnivorous (comparable to pigs, humans, or black bears). Where whales differ is that the margin of the dome closest to the midline of the skull, called the involucrum, is extremely thick, dense, and highly mineralized. 1846. It was about the size of a large sea lion. It had relativity small front fins, a smaller fin located on the underside of the tale and a large tail fin. Systematic Biology 48, 455-490. Richard Harlan reviewed the fossils, which were unlike any he had seen before. & Geisler, J. H. 1999. Pakicetus has not been found from deposits of the Tethys Sea but instead from adjacent river and floodplain deposits, which also yield bones of land dwelling mammals. Image credit: NASA / Apollo 17. Geisler, J.G.,Theodor, J.M. Though not a series of direct ancestors and descendants, each genus represents a particular stage of whale evolution. In fact, some fossil teeth that were once identified as mesonychids are now known to have come from archaeocetes. It had limbs like a land animal and webbed toes in replacement for fins, suggesting that it recently changed from land to water through evolution. Anatomy: For this reason, scientists had long believed that mesonychids were the direct ancestor of Cetacea, but the discovery of well-preserved hind limbs of archaic cetaceans, as well as more recent phylogenetic analyses now indicate cetaceans are more closely related to hippopotamids and other artiodactyls than they are to mesonychids, and this result is consistent with many molecular studies. harvnb error: no target: CITEREFJordiAnton2002 (, J. D. Archibald. Mesonychids limbs and tail description. Posted by ; dollar general supplier application; USA Distributor of MCM Equipment mesonychids limbs and tail Cetaceans, like many other mammals, have ear bones enclosed in a dome of bone on the underside of their skulls called the auditory bulla. homestead high school staff. these animals were torpedo-shaped and had flexible and elongated vertebrae, huge skulls more than 3 feet long, curved front teeth, serrated cheek teeth, flexible necks, twin flippers derived from forelegs, small dorsal fins, and long, fluked tails. [11] The similarity in dentition and skull may be the result of primitive ungulate structures in related groups independently evolving to meet similar needs as predators; some researchers have suggested that the absence of a first toe and a reduced metatarsal are basal features (synapomorphies) indicating that mesonychids, perissodactyls, and artiodactyls are sister groups. The fact that it was found in freshwater deposits and did not have specializations of the inner ear for underwater hearing showed that it was still very early in the aquatic transition, and Gingerich and Russell thought ofPakicetusas an amphibious intermediate stage in the transition of whales from land to sea, though they added the caveat that Postcranial remains [bones other than the skull] will provide the best test of this hypothesis. The scientists had every reason to be cautious, but the fact that a transitional whale had been found was so stupendous that full-body reconstructions ofPakicetusappeared in books, magazines and on television. 1999. Mesonychids in North America were by far the largest predatory mammals during the early Paleocene to middle Eocene. Mesonychids were the first mammalian carnivores after the extinction of the dinosaurs.. So why do these embryos look so much alike? A new species of mesonychian mammal from the lower Eocene of Mongolia and its phylogenetic relationships. As I recall Prothero et al. In the meantime, scientists speculated about what the ancestors of whales might have been like. Please make a tax-deductible donation if you value independent science communication, collaboration, participation, and open access. This conflict makes his soul a battlefield, where the forces that wish this reconciliation fight those that do not and reject the alternative solutions they offer. Mesonychids first appeared in the early Paleocene, went into a sharp decline at the end of the Eocene, and died out entirely when the last genus, Mongolestes, became extinct in the early Oligocene. But where skeletons are known, they indicate that mesonychids had large heads with strong jaw muscles, relatively long necks, and robust bodies with robust limbs that could run effectively but not rotate the hand or reach out to the side. Mesonychids probably originated in China, where the most primitive mesonychid, Yangtanglestes, is known from the early Paleocene. "Triisodontidae" may be paraphyletic. Some of the sediment attached to the bone contained small shells that showed that the large creature had once lived in an ancient sea, but little more could be said with any certainty. His attention to such tiny details ultimately settled the identification of the sea monster. They were also most diverse in Asia where they occur in all major Paleocene faunas. The group of animals that had the most features common to the earliest primitive whales found was called the Mesonychids . The following airs here in the UK tonight (Thursday 30th June 2011), Channel 4. And there is yet more to come: the hapalodectids are next. 2008. [4] [5] Like other mesonychids, the toes ended in small hooves. These are considered closely related to the even- toed hoofed animals of today known as artiodactyls, with many branches evolving intomodern deer, cattle, pigs, and hippos. By the time the first mammals evolved 200 million years ago, however, dinosaurs were the dominant vertebrates. Size: Madar, S. I. Prothero, D. R., Manning, E. M. & Fischer, M. 1988. A few years later, a scientist handling a different specimen with his colleagues pulled out a bone from the skull, dropped it, and it shattered on the floor. It appeared that Van Valen had been right, andPakicetuswas just the sort of marsh-dwelling creature he had envisioned. 133-161. Good remains of P. ossifraga show that it was a large animal of 60-70 kg [skull of Sinonyx jiashanensis from Late Paleocene China shown below, from Zhou et al. The bulla is the bone of the skull that formed the floor of a cavity that housed the middle ear ossicles (the malleus, incus, and stapes). [5]. For this reason, scientists had long believed that mesonychids were the direct ancestor of Cetacea, but the discovery of well-preserved hind limbs of archaic cetaceans, as well as more recent phylogenetic analyses[8][9][10] now indicate cetaceans are more closely related to hippopotamids and other artiodactyls than they are to mesonychids, and this result is consistent with many molecular studies. Archaeocetes had a double-pulley astragalus, confirming that cetaceans had evolved from artiodactyls. The order is sometimes referred to by its older name Acreodi. American Zoologist 41, 487-506. Another extinct whale calledSqualodon, a fossil dolphin with a wicked smile full of triangular teeth, similarly hinted that whales had evolved from meat-eating ancestors. The similarity in dentition and skull may be the result of primitive ungulate structures in related groups independently evolving to meet similar needs as predators; some researchers have suggested that the absence of a first toe and a reduced metatarsal are basal features (synapomorphies) indicating that mesonychids, perissodactyls, and artiodactyls are sister groups. For another, more detailed, article about Mesonychidae, see, Sarah L. Shelley, Thomas E. Williamson, Stephen L. Brusatte, Resolving the higher-level phylogenetic relationships of Triisodontidae (Condylarthra) within Placentalia, October 2015, Society of Vertebrate Paleontology (abstract), "New Mesonychid mammals found from lower Paleogene of Erlian Basin, Nei Mongol", "Carnivores, creodonts and carnivorous ungulates: Mammals become predators", 10.1671/0272-4634(2000)020[0387:ANSOAM]2.0.CO;2, "Mesonyx and the other mesonychid mesonychians (mesonychians part IV) | ScienceBlogs", "The position of Hippopotamidae within Cetartiodactyla", "Evidence from milk casein genes that cetaceans are close relatives of hippopotamid artiodactyls", https://en.wikipedia.org/w/index.php?title=Mesonychid&oldid=1115476645, This page was last edited on 11 October 2022, at 17:25. The largest species are considered to have been scavengers. Long-snouted marsupial martens and false thylacines, Marsupial 'bears' and marsupial sabre-tooths, Because it would be wrong not to mention a sperm whale named like a tyrannosaur, http://viergacht.deviantart.com/art/Harpagolestes-133779748, http://www.archive.org/details/introductiontoos1885flow, The Lab Leak Theory Was Dismissed As Trump Xenophobia - Now Deniers Say It Was Not Accepted Because of Trump Xenophobia, DAN5/P1: Homo Erectus Early Cranial Capacity Was More Like Australopiths Such As 'Lucy', DART Made A Big Difference In Ability To Accurately Calculate Asteroid Deflections, The Subsidies Paradox: Affordable Food Versus The Environment, Degrowth communism as asolution for climate change. Mesonychids have often been reconstructed as resembling wolves albeit superficially, but they would have appeared very different in life. The only tail vertebra found is long, making it likely that the tail was also long. We use cookies to see how our website is performing. In C. M. Janis, K. M. Scott, and L. L. Jacobs (eds. He wasnt certain, though. The skull ofPakicetusexhibited just this condition. They first appeared in the Early Paleocene, undergoing numerous speciation events during the Paleocene, and Eocene. (1995); and to Cete by Archibald (1998);[7] and to Mesonychia by Carroll (1988), Zhou et al. The history of life: looking at the patterns, Pacing, diversity, complexity, and trends, Alignment with the Next Generation Science Standards, Information on controversies in the public arena relating to evolution. -Jack Handey Mesonychids e.g. This page was last updated at 2022-07-17 03:07 UTC. Not to toot my own horn, but I found this article very inspiring. Pachyaena Pakicetus Ambulocetus Rodhocetus Basilosaurus Zygorhiza Year reported Country where found Geological age (mya) Habitat (land, fresh water, shallow sea, open ocean) Skull, teeth, ear structure types most like. By the late Eocene, archaeocete whales had spread to many parts of the world. Mesonychids were not the ancestors of whales, and hippos are now known to be the closest living relatives to whales. Nearly all mesonychids are, on average, larger than most of the Paleocene and Eocene creodonts and miacoid carnivorans. The foot was compressed for efficient running with the axis between the third and fourth toes (paraxonic); it would have looked something like a hoofed paw. As you well know, normal matter here on Earth is, Mesonyx and the other mesonychid mesonychians (mesonychians part IV), Because we all love Paleogene 'ungulates', Five things you didn't know about armadillos. One particular ankle bone, the astragalus, had the potential to settle the debate. The cervical vertebrae were relatively long, compared to those of modern whales; Ambulocetus must have had a flexible neck. Nature 361:444-445. If mathematical, chemical, physical and other formulas are not displayed correctly on this page, please useFirefox or Safari, This article is about the prehistoric ungulate. But, because they are mammals, we know that they must . While, as noted earlier and elsewhere, Pachyaena and other mesonychids are often imagined as wolf-like, the good data we have on the osteology of this animal show that it was quite different from a canid in many respects. [12] However, the close grouping of whales with hippopotami in cladistic analyses only surfaces following the deletion of Andrewsarchus, which has often been included within the mesonychids. For this reason, scientists had long believed that mesonychids were the direct ancestor of Cetacea, but the discovery of well-preserved hind limbs of archaic cetaceans, as . These later mesonychids had hooves, one on each toe, with four toes on each foot. 1998. Basilosaurus is characterized by extremely elongate vertebrae (three times as long as those in most other basilosaurids, relative to vertebral width), a very high degree of flexibility in the vertebral column, a high number of vertebrae, and an incredibly elongate body form in general. In some localities, multiple species or genera coexisted in different ecological niches. Theropods, several crurotarsan clades and, to a certain degree, even entelodonts did just fine with ziphodont teeth; Australia's top mammalian predator wasn't a dasyurid, but *Thylacoleo*. Update now. homestead high school staff. An unrelated early group of mammalian predators, the creodonts, also had unusually large heads and limbs that traded flexibility for efficiency in running; large head size may be connected to inability to use the feet and claws to help catch and process food, as many modern carnivorans do. > traditional characterisation as archaic,'inferior' - . These earliest cetaceans were not like the whales we know today, and only recently have paleontologists been able to recognize them. A typical example of these animals (e.g. - ., Zhai, R. J., Gingerich, P. D. & Chen, L. Z. It is my understanding that most of the world was more forested, with far less open grassland than there is now. These animals would have migrated to North America via the Bering land bridge. Pakicetus had a dense and thickened auditory bulla, which is a characteristic of all cetaceans. [13][14] One possible conclusion is that Andrewsarchus has been incorrectly classified. Dissacus was a jackal-sized predator that has been found all over the Northern Hemisphere,[3] but species of a closely related or identical genus, Ankalagon, from the early to middle Paleocene of New Mexico, were far larger, growing to the size of a bear. Advertising Notice malleus, incus, stapes), which transmitted the sound to the organ of hearing. The cervical vertebrae were relatively long, compared to those of modern whales; Ambulocetus must have had a flexible neck. Learn Mesonychid facts for kids. These "wolves on hooves" are an extinct order of carnivorous mammals, closely related to artiodactyls.. Mesonychids first appeared in the early Palaeocene with the genus Dissacus.They went in decline at the end of the Eocene, and became extinct in the early Oligocene. Van Valen hypothesized that some mesonychids may have been marsh dwellers, mollusk eaters that caught an occasional fish, the broadened phalanges [finger and toe bones] aiding them on damp surfaces. A population of mesonychids in a marshy habitat might have been enticed into the water by seafood. \+
\N\?luW Rose, K. D. & O'Leary, M. A. In Asia, the record of their history suggests they grew gradually larger and more predatory over time, then shifted to scavenging and bone-crushing lifestyles before the group became extinct. A later genus, Pachyaena, entered North America by the earliest Eocene, where it evolved into species that were at least as large. Goodbye Tet Zoo ver 2. American Museum Novitates 3344, 1-53. They were also most diverse in Asia, where they occur in all major Paleocene faunas. Some mesonychids are reconstructed as predatory (comparable to canids), others as scavengers or carnivore-scavengers with bone-crushing adaptations to their teeth (comparable to the large hyenas), and some as omnivorous (comparable to pigs, humans, or black bears). They were endemic to North America and Eurasia during the Early Paleocene to the Early Oligocene, and were the earliest group of large carnivorous mammals in Asia.They are not closely related to any living mammals. About 375 million years ago, the first tetrapodsvertebrates with arms and legspushed themselves out of the swamps and began to live on land. There are currently 4 species of Pakicetus: Pakicetis inachus, P. attocki, P. calcis, P. chittas. There was only one other kind of creature with an inner ear that matched: a whale. O'Leary, M. A. This idea was contested by O'Leary (1998), however, and it's mostly agreed that, while Dissacus is a basal mesonychid, Hapalodectes is a member of another mesonychian clade that we'll be looking at later on. While analyzing the relationships of ancient meat-eating mammals in 1966, however, the evolutionary biologist Leigh Van Valen was struck by the similarities between an extinct group of land-dwelling carnivores called mesonychids and the earliest known whales. This puts mesonychids as a distant relative of cetaceans rather than an ancestor, and their somewhat similar morphology was possibly a result of convergent evolution. ), Evolution of Tertiary Mammals of North America 1:292-331, "The Mammals that Conquered the Seas; New Fossils and DNA Analyses Elucidate the Remarkable History of Whales", "Relationships of Cetacea (Artiodactyla) Among Mammals: Increased Taxon Sampling Alters Interpretations of Key Fossils and Character Evolution", Mammoths, Sabertooths, and Hominids: 65 Million Years of Mammalian Evolution in Europe, "Mesonychids from Lushi Basin, Henan Province, China", https://en.wikipedia.org/w/index.php?title=Mesonychidae&oldid=1049612098, Short description is different from Wikidata, Creative Commons Attribution-ShareAlike License 3.0, This page was last edited on 12 October 2021, at 20:41. In 2001, archaeocetes possessing this bone were finally described, and the results were unmistakable. Origins of underwater hearing in whales. Mesonychids possess unusual triangular molar teeth that are similar to those of Cetacea (whales and dolphins), especially those of the archaeocetes, as well as having similar skull anatomies and other morphologic traits. Typified by hooves and sometimes by horns or antlers, today these creatures fill most of the existing niches for large herbivores all over the world. Szalay, F. S. & Gould, S. J. They may not have included hypercarnivores (comparable to felids); their teeth were not as effective at cutting meat as later groups of large mammalian predators. These "wolves on hooves" were probably one of the more important predator groups in the late Paleocene and Eocene ecosystems of Europe (which was an archipelago at the time), Asia (which was an island continent), and North America. Mesonychid dentition consisted of molars modified to generate vertical shear, thin blade-like lower molars, and carnassial notches, but no true carnassials. Although they share a common ancestor, the Carnivora are split into two quite well-defined groups that are broadly dog-like, the . This, in combination with its inferred diet (see below) and inferred ability to walk on the bottom, suggests that it attacked its prey from below. 292-331. Mesonychia ("middle claws") is an extinct taxon of small- to large-sized carnivorous ungulates related to artiodactyls. For another, more detailed, article about Mesonychidae, see, Creative Commons Attribution-ShareAlike License. The order is sometimes referred to by its older name "Acreodi". (1995) found Mongolonyx and Mongolestes (both from Eocene Asia) to be part of this clade as well. However, the close grouping of whales with hippopotami in cladistic analyses only surfaces following the deletion of Andrewsarchus, which has often been included within the mesonychids. Cookie Policy That the whole South should commit itself to the principle that the colored people have a right to be educated is an immense acquisition to the cause of popular education.Fannie Barrier Williams (18551944), America loves the representation of its heroes to be not just larger than life, but stupendously, awesomely bigger than anything else. For more than a century, our knowledge of the whale fossil record was so sparse that no one could be certain what the ancestors of whales looked like. While the limb proportions and hoof-like phalanges indicate cursoriality, the limbs were relatively stout and show that it cannot have been a long-distance pursuit runner. - . - . The prezygapophyses should be the ones with the articular surfaces directed medially, and the postzygapophyses those with the articular surface directed laterally, more similar to the condition in other tetrapods (and mammals, according to Fowler, http://www.archive.org/details/introductiontoos1885flow). Basilosaurus did share some traits with marine reptiles, but this was only a superficial case of convergenceof animals in the same habitat evolving similar traitsbecause both types of creature had lived in the sea. Nature 458:E1-E4. Postcranial skeleton of the early Eocene mesonychid Pachyaena (Mammalia: Mesonychia). Writing to his staunch advocate T.H. Contributions are fully tax-deductible. Based on this, Pakicetus retained the ability to hear airborne sound. Pachyaena , or Sinonyx ) looked . When the unnerved scientists gathered the fragments, they noticed that the bone now revealed the inner ear. One possible conclusion is that Andrewsarchus is not a mesonychid, but rather closely allied with hippopotamids. Pakicetus had a long snout; a typical complement of teeth that included incisors, canines, premolars, and molars; a distinct and flexible neck; and a very long and robust tail. Mesonychidae was named by Cope (1880). Hippopotamus and whale phylogeny. The offender this time is Nick Saunders of the University of Bristol, writing in Current World Archaeology #62 (Dec/Jan, available on Academia.edu). The sound passage via the external ear of Pakicetus was intact and was similar to that of other mammals. He envisioned a hypothetical cetacean ancestor easing itself into the shallows: We may conclude by picturing to ourselves some primitive generalized, marsh-haunting animals with scanty covering of hair like the modern hippopotamus, but with broad, swimming tails and short limbs, omnivorous in their mode of feeding, probably combining water plants with mussels, worms, and freshwater crustaceans, gradually becoming more and more adapted to fill the void place ready for them on the aquatic side of the borderland on which they dwelt, and so by degree being modified into dolphin-like creatures inhabiting lakes and rivers, and ultimately finding their way into the ocean. Copyright 2010. queen of the south why did javier kill tony. The postcranial skeleton of early Eocene pakicetid cetaceans. Since other carnivores such as the creodonts and Carnivora were either rare or absent in these animal communities, mesonychids most likely dominated the large predator niche in the Paleocene of Asia. Glad you tooted. However, it had rather short, strong hind limbs, with huge feet (each toe with a tiny mesonychid-type hoof!). Discuss with your teammates what traits you would expect to find (in the head , limbs , tail , . Blubber, blowholes and flukes are among the hallmarks of the roughly 80 species of cetaceans (whales, dolphins and porpoises) alive today. I look forward to it. Over time, the family evolved foot and leg adaptations for faster running, and jaw adaptations for greater bite force. 1966. Most paleontologists now doubt that whales are descended from mesonychids, and instead suggest that whales are either descended from, or share a common ancestor with, the anthracotheres, the semi-aquatic ancestors of hippos. The current uncertainty may, in part, reflect the fragmentary nature of the remains of some crucial fossil taxa, such as Andrewsarchus. Samples from the teeth of Pakicetus yield oxygen isotope ratios and variation that indicate Pakicetus lived in freshwater environments, such as rivers and lakes. For this reason, scientists had long believed that mesonychids were the direct ancestor of Cetacea, but the discovery of . > predators might have some credit after all. All rights reserved. Mesonychid dentition consisted of molars modified to generate vertical shear, thin blade-like lower molars, and carnassial notches, but no true carnassials. [7] Some genera may need revision to clarify the actual number of species or remove ambiguity about genera (such as Dissacus and Ankalagon).[5]. Based on the orientations of the wear facets, Pakicetus sheared its prey into smaller pieces before swallowing. The large tail of Pakicetus is possibly a specialization for aquatic locomotion, although exactly how is unclear. Privacy statement. Journal of Paleontology 81:176-200. The earliest known archaeocetes were creatures like the 53-million-year-oldPakicetusand the slightly olderHimalayacetus. A number of other mesonychian taxa have conventionally been included within Mesonychidae. They were endemic to North America and Eurasia during the Early Paleocene to the Early Oligocene, and were the earliest group of large carnivorous mammals in Asia. Thus it is unclear if it was an active predator or if instead it ambushed unsuspecting prey that wandered too closely. %PDF-1.2
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201-234. mesonychids limbs and tailbiblical counseling raleigh, nc | An unrelated early group of mammalian predators, the creodonts, also had unusually large heads and limbs that traded flexibility for efficiency in running; large head size may be connected to inability to use the feet and claws to help catch and process food, as many modern carnivorans do. Riley Black is a freelance science writer specializing in evolution, paleontology and natural history who blogs regularly for Scientific American. . Mesonychid taxonomy has long been disputed and they have captured popular imagination as "wolves on hooves," animals that combine features of both ungulates and carnivores. There were bone-cracking scavengers, small jackal or fox-like generalists, large wolf-like hunters, and so on. With a short lower spine stiffened by revolute joints, they would have run with stiff backs like modern ungulates rather than bounding or loping with flexible spines like modern Carnivorans. Blubber, blowholes and flukes are among the hallmarks of the roughly 80 species of cetaceans (whales, dolphins and porpoises) alive today. So, in the sheep figure, anterior is to the left and above. This really is the end. Pakicetus inachus, a New Archaeocete (Mammalia, Cetecea) from the early-middle Eocene Kuldana Formation of Kohat (Pakistan). zatarain's chicken fry mix ingredients New Lab; brown service funeral home obituaries; Skulls and teeth have similar features to early whales, and the family was long thought to be the ancestors of cetaceans. It was presented as a stumpy-legged, seal-like creature, an animal caught between worlds. If the astragalus of an early archaeocete could be found it would provide an important test for both hypotheses. I've been in Romania and Hungary where I had a great time - saw lots of neat animals (fossil and living) and hung out with some neat people. Mesonychid dentition consisted of molars modified to generate vertical shear, thin blade-like lower molars, and carnassial notches, but no true carnassials. Technically speaking, the term "mesonychid" refers specifically only to the members of the family Mesonychidae, such as the species of the genus Mesonyx. Unlike all modern and possibly all other fossil cetaceans, it had four fully functional, long legs. Early mesonychids probably walked on the flats of their feet (plantigrade), while later ones walked on their toes (digitigrade). Take a look at our home planet, Earth, and one of the things you'll notice is that over 70% of the surface is coated in water. They had an elongated skull and triangular teeth, which are similar to whales. Ankalagon was larger than Dissacus (though the only known species, A. saurognathus, was originally described as a species of Dissacus) and is sometimes said to have been North America's first large mammalian predator. The eyes of Pakicetus faced to the side and slightly upward. 1981. (2009).[8]. Which embryo is human? All our content comes from Wikipedia and under the Creative Commons Attribution-ShareAlike License. Which were more reliable, teeth or genes? As described in the comments above, all known skeletons of Pakicetus are composites created by gathering isolated bones. These forms eventually died out, but not before giving rise to the early representatives of the two groups of whales alive today, the toothed whales and the baleen whales. It had a long muzzle, teeth that were very similar to later archaeocetes, a reduced . It was a wolf-like animal, not the slick, seal-like animal that had originally been envisioned. These features suggest to some authors that Harpagolestes was a carrion feeder (Szalay & Gould 1966, Archibald 1998).