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. 2023 Smithsonian Magazine | READ MORE. In some localities, multiple species or genera coexisted in different ecological niches. Early mesonychids probably walked on the flats of their feet (plantigrade), while later ones walked on their toes (digitigrade). Accept Cookies, Osteopathic Manipulative Medicine Research. The bones were so numerous that in some fields they were destroyed because they interfered with cultivating the land. The cervical vertebrae were relatively long, compared to those of modern whales; Ambulocetus must have had a flexible neck. The group of animals that had the most features common to the earliest primitive whales found was called the Mesonychids . The jaw contained teeth that differed in size and shape, a characteristic of mammals but not most reptiles. \+ \N\?luW 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. He thought they might be of scientific interest and sent a package to the American Philosophical Society in Philadelphia. "Triisodontidae" may be paraphyletic. Of course, there are a few others: Dissacusium and Jiangxia from the Asian Paleocene, Guiletes from the Asian Eocene, and Hessolestes from the North American Eocene. Mesonychids varied in size; some species were as small as a fox, others as large as a horse. Limbs and tail: Description; Did it swim? References Consulted: 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. While later mesonychids evolved a suite of limb adaptations for running similar to those in both wolves and deer, their legs remained comparatively thick. 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. 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. Hr6prGO]di3nO[wK]DQ %H'U : yqsOa&'gR@&,CEN~I.{8Kei^I&. 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. Age: Madar, S. I. In Benton, M. J. That's what he does! Harpagolestes, known from several North American and Asian species, is a notably robust-skulled mesonychid with proportionally large canines, a deep lower jaw, and relatively broad post-canine teeth that are often heavily worn [skull of H. uintensis shown here, from Szalay & Gould (1966)]. Mesonychidae - . 1998. One possible conclusion is that Andrewsarchus is not a mesonychid, but rather closely allied with hippopotamids. & Geisler, J. H. 1999. Looking back at it now, that very first ver 2 post is rather odd. [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. Writing to his staunch advocate T.H. 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. The only tail vertebra found is long, making it likely that the tail was also long. We do not collect or store your personal information, and we do not track your preferences or activity on this site. The link between other ungulates and whales is thought to be mesonychids, extinct four-legged mammals that sometimes feasted on fish at river edges. It was thick and highly mineralized, just like the bone in whale ears. The fore limbs are so much shorter than the hind limbs that the animal customarily sat on its haunches when on land. 1992, O'Leary & Rose 1995, Rose & O'Leary 1995), and also widespread, with specimens being known from the Paleocene and Eocene of eastern Asia, the Eocene and perhaps Paleocene of North America, and the Eocene of Europe. Unlike all modern and possibly all other fossil cetaceans, it had four fully functional, long legs. It was only about 10 million years after this extinctionand more than 250 million years since the earliest tetrapods crawled out onto landthat the first whales evolved. Most paleontologists now doubt that whales are descended from mesonychids, and instead suggest mesonychians are descended from basal ungulates, and that cetaceans are descended from advanced ungulates (Artiodactyla), either deriving from, or sharing a common ancestor with, anthracotheres (the semiaquatic ancestors of hippos). In the space of just three decades, a flood of new fossils has filled in the gaps in our knowledge to turn the origin of whales into one of the best-documented examples of large-scale evolutionary change in the fossil record. USA Distributor of MCM Equipment mesonychids limbs and tail Nature 458:E1-E4. Darwin was widely ridiculed for this passage. 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. Diet: However, recent work indicates that Pachyaena is paraphyletic (Geisler & McKenna 2007), with P. ossifraga being closer to Synoplotherium, Harpagolestes and Mesonyx than to P. gigantea. Yantanglestes from Paleocene Asia (originally described as a species of Dissacus) is also thought to be a basal member of the group. Cetaceans, like many other mammals, have ear bones enclosed in a dome of bone on the underside of their skulls called the auditory bulla. 1998. Glad you tooted. Ambulocetus's skull was quite cetacean (Novacek 1994). With the permission of the publisher, Bellevue Literary Press. Mesonychids possess unusual triangular molar teeth that are similar to those of Cetacea (whales and dolphins), especially those of the archaeocetids, as well as having similar skull anatomies and other morphologic traits. 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). Mesonychid dentition consisted of molars modified to generate vertical shear, thin blade-like lower molars, and carnassial notches, but no true carnassials. Pakicetus looked very different from modern cetaceans, and its body shape more resembled those of land dwelling, hoofed mammals. There were bone-cracking scavengers, small jackal or fox-like generalists, large wolf-like hunters, and so on. 1999. For this reason, scientists had long believed that mesonychids were the direct ancestor of Cetacea, but the discovery of . malleus, incus, stapes), which transmitted the sound to the organ of hearing. Mesonychia ("middle claws") is an extinct taxon of small- to large-sized carnivorous ungulates related to artiodactyls. Like the Paleocene family Arctocyonidae, mesonychids were once viewed as primitive carnivorans, and the diet of most genera probably included meat or fish. Critics took it to mean he was proposing that bears were direct ancestors of whales. & Rose, K. D. 1995. Cookie Policy Mesonychids probably originated in China, where the most primitive mesonychid, Yangtanglestes, is known from the early Paleocene. Inside, If you didn't know, I've been away. Privacy statement. whale or land mammal? You're welcome. Mesonychids exemplified a wide variety of appearances, ranging from those similar to wolves, hyenas, bears, and dogs (Jehle 2010). Based on this, Pakicetus retained the ability to hear airborne sound. There are currently 4 species of Pakicetus: Pakicetis inachus, P. attocki, P. calcis, P. chittas. (ed) The Phylogeny and Classification of the Tetrapods, Volume 2: Mammals. 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 indicates that cetaceans are more closely related to hippopotamids and other artiodactyls than they are to mesonychids, and this result is consistent with many molecular studies. Rose, K. D. & O'Leary, M. A. O'Leary, M. A. 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. One unresolved question is how exactly did Pakicetus catch its prey? Mesonychids are a mostly Eocene group that originated in the Paleocene; Mesonyx, from the Middle Eocene of North America, was the first member of the group to be named (Cope published the name in . The only other possible aquatic characteristics evident in its skeleton are scars on the toe bones that indicate strong muscles for separating the toes. New York: Fowler & Wells. mesonychids limbs and tail. 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. These animals would have migrated to North America via the Bering land bridge. Technically speaking, the term "mesonychid" refers specifically only to the members of the family Mesonychidae, such as the species of the genus Mesonyx. 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. 2006. & Gingerich, P. D. 1992. It is my understanding that most of the world was more forested, with far less open grassland than there is now. Adapted fromWritten in Stone: Evolution, the Fossil Record, and Our Place in Nature, by Brian Switek. Thewissen, J.G.M., Williams, E.M., Roe, L.J., and Hussain, S.T.. 2001. Locomotion: Inside Nature's Giants: a major television event worthy of praise and accolade. Once they had begun swimming for their supper, succeeding generations would become more and more aquatically adapted until something as monstrous as a whale evolved. Reconstructions of pakicetids that followed the discovery of composite skeletons often depicted them with fur; however, given their close relationships with hippos, they more likely had sparse body hair. Pioneers who cleared land in Alabama and Arkansas frequently found enormous round bones. Study of the rest of the skeleton also revealed thatIndohyushad bones marked by a similar kind of thickening, an adaptation shared by mammals that spend a lot of time in the water. > predators might have some credit after all. 201-234. 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. Volume 1: Terrestrial Carnivores, Ungulates, and Ungulatelike Mammals. Compared to what we're used to in modern mammals, it also seems that mesonychids would have looked big-headed and also long-necked. | Part I! See you there. - ., Zhai, R. J., Gingerich, P. D. & Chen, L. Z. They were also most diverse in Asia, where they occur in all major Paleocene faunas. - . Journal of Vertebrate Paleontology 15, 401-430. As E.D. The hypothesis that Ambulocetus lived an aquatic life is also supported by evidence from stratigraphy Ambulocetus's fossils were recovered from sediments that probably comprised an ancient estuary and from the isotopes of oxygen in its bones. Thewissen, J. G. M., Cooper, L. N., Clementz, M. T., Bajpai, S. & Tiwari, B. N. 2007. It's on the blood-feeding behaviour of, So sorry for the very short notice. Riley Black is a freelance science writer specializing in evolution, paleontology and natural history who blogs regularly for Scientific American. Early mesonychids probably walked on the flats of their feet (plantigrade), while later ones walked on their toes (digitigrade). Huxley replied that there could be little doubt thatBasilosaurusprovided clues as to the ancestry of whales. [1], 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. 2_%v>sr&u ! 1995]. Nature 361:444-445. Archaic ungulates ("Condylarthra"). Richard Harlan reviewed the fossils, which were unlike any he had seen before. 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). These hoofed predators came in diverse forms, from tiny to horse-sized. Thus it is unclear if it was an active predator or if instead it ambushed unsuspecting prey that wandered too closely. can general dentists do bone grafts; apple tartlets with pillsbury pie crust; what bulbs will squirrels not eat; can cinnamon cause a miscarriage; mesonychids limbs and tail. 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. I think the prezygapophyses and postzygapophyses are incorrectly identified in the essay. Together these fossil whales hung in a kind of scientific limbo, waiting for some future discovery to connect them with their land-dwelling ancestors. These features suggest to some authors that Harpagolestes was a carrion feeder (Szalay & Gould 1966, Archibald 1998). 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. All our content comes from Wikipedia and under the Creative Commons Attribution-ShareAlike License. One genus, Dissacus, had successfully spread to Europe and North America by the early Paleocene. Mesonychians were long considered to be creodonts, but have now been removed from that order and placed in three families (Mesonychidae, Hapalodectidae, and Triisodontidae), either within their own order, Mesonychia, or within the order Condylarthra as part of the cohort or superorder Laurasiatheria. However, even though they are similar in appearance to land animals, some consider Mesonychids to be ancestors of whales. There is evidence to suggest that some genera were sexually dimorphic. And there is yet more to come: the hapalodectids are next. In the meantime, scientists speculated about what the ancestors of whales might have been like. deer, camel, pigs) and appears to be adapted for running at high speeds. [4] [5] Like other mesonychids, the toes ended in small hooves. The head End of preview Want to read all 2 pages? Isotopic records from early whales and sea cows: contrasting patterns of ecological transition. Synoplotherium may also be part of this Harpagolestes-Mesonyx clade, and Zhou et al. Not to toot my own horn, but I found this article very inspiring. 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. Pachyaena , or Sinonyx ) looked . The American Phrenological Journal and Miscellany, Vol. Size: mesonychids limbs and tailokinawan sweet potato tempura recipe. Mesonychids probably originated in Asia, where the most primitive mesonychid, Yangtanglestes, is known from the early Paleocene. 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). Upload your study docs or become a member. Cope admitted in an 1890 review of whales: The order Cetacea is one of those of whose origin we have no definite knowledge. This state of affairs continued for decades. And another matter, given that mesonychian meat processing really didn't seem to be up to snuff, compared to modern carnivorans, their traditional characterisation as archaic,'inferior' predators might have some credit after all. Mesonychidae was named by Cope (1880). Raoellids likeIndohyuswere the closest relatives to whales, with hippos being the next closest relatives to both groups combined. Harlan thought the bones were most similar to those of extinct marine reptiles such as the long-necked plesiosaurs and streamlined ichthyosaurs. 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. The molars have steeply inclined wear facets that formed when the upper and lower teeth contacted during chewing. Given that both Creagh and Bry said they had seen intact vertebral columns in excess of 100 feet in length, the living creature must have been one of the largest vertebrates to have ever lived. 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. mesonychids limbs and tailbiblical counseling raleigh, nc | A new species of mesonychian mammal from the lower Eocene of Mongolia and its phylogenetic relationships. Its type genus is Mesonyx. 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. > to be up to snuff, compared to modern carnivorans, their He could not imagine that early cetaceans used their limbs to swim and then switched to tail-only propulsion at some later point. In fact, some fossil teeth that were once identified as mesonychids are now known to have come from archaeocetes. New morphological evidence for the phylogeny of Artiodactyla, Cetacea, and Mesonychidae. Darwin had done no such thing, but the jeering caused him to modify the passage in subsequent editions of the book. Eocene Epoch. The postcranial skeleton of early Eocene pakicetid cetaceans. Though not a series of direct ancestors and descendants, each genus represents a particular stage of whale evolution. Systematic Biology 48, 455-490. [13][14] One possible conclusion is that Andrewsarchus has been incorrectly classified. 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. Some settlers used them as fireplace hearths; others propped up fences with the bones or used them as cornerstones; slaves used the bones as pillows. Mesonychids possess unusual triangular molar teeth that are similar to those of Cetacea (whales and dolphins), especially those of the archaeocetids, as well as having similar skull anatomies and other morphologic traits. Yep, you are correct - a stupid error that I will now go correct, thanks. The position of Cetacea within Mammalia: phylogenetic analysis of morphological data from extinct and extant taxa. Its skeleton bears no evidence that it could move fast in the water. The manus of Pachyaena gigantea (Mammalia: Mesonychia). The current uncertainty may, in part, reflect the fragmentary nature of the remains of some crucial fossil taxa, such as Andrewsarchus. Mesonychids have often been reconstructed as resembling wolves albeit superficially, but they would have appeared very different in life. Normally, sound waves in air are reflected when they encounter a skull because of the great difference in density between bone and air; however, the density of water is much closer to that of bone. 1995. Beginning in 1983, paleontologists have. [5], Most paleontologists now doubt that whales are descended from mesonychids, and instead suggest mesonychians are descended from basal ungulates, and that cetaceans are descended from advanced ungulates (Artiodactyla), either deriving from, or sharing a common ancestor with, anthracotheres (the semiaquatic ancestors of hippos). Living at about the same time as the remingtonocetids was another group of even more aquatically adapted whales, the protocetids. These "wolves on hooves" are an extinct order of carnivorous mammals, closely related to artiodactyls. The order is sometimes referred to by its older name "Acreodi". Journal of Vertebrate Paleontology 15, 855-859. What springs to mind when you think of a whale? On January 23rd 2007, Tet Zoo ver 2 - the ScienceBlogs version of Tetrapod Zoology - graced the intertoobz for the first time. 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. Plenum Press (New York), pp. ), 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. Skull of a new mesonychid (Mammalia, Mesonychia) from the Late Paleocene of China. The skull ofPakicetusexhibited just this condition. They were also most diverse in Asia where they occur in all major Paleocene faunas. The molars were laterally compressed and often blunt, and were probably used for shearing meat or crushing bones. Cambridge University Press, pp. The skeleton of Pakicetus resembles those of many other even-toed hoofed mammals (e.g. Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls. Relatively complete remains were described by Geisler & McKenna (2007) and confirm that the first toe was absent and that the first metatarsal was highly reduced: this is also the case in basal perissodactyls, cetaceans and artiodactyls, and it might be a synapomorphy uniting these groups. [5] They would have resembled no group of living animals. Mesonychids in North America were by far the largest predatory mammals during the early Paleocene to middle Eocene. However, these specimens generally lack forelimbs, hind limbs, and tails. The mesonychids mentioned here are not, of course, the only members of the group. However, they also found Dissacus to be paraphyletic with respect to other mesonychids, so further study and perhaps some taxonomic revision is needed [Greg Paul's reconstruction of Ankalagon shown in adjacent image]. Inside Nature's Giants: polar bear special, Nick Saunders's Battlefield Archaeology Is Much Better Than Everybody Else's, Dark Matter: what it does, what it doesn't do. They first appeared in the Early Paleocene, undergoing numerous speciation events during the Paleocene, and Eocene. But, because they are mammals, we know that they must have evolved from land-dwelling ancestors. In 2007, Thewissen and other collaborators announced thatIndohyus, a small deer-like mammal belonging to a group of extinct artiodactyls called raoellids, was the closest known relative to whales. It was presented as a stumpy-legged, seal-like creature, an animal caught between worlds. The fossil remains of such a creature remained elusive. In 1832, a hill collapsed on the Arkansas property of Judge H. Bry and exposed a long sequence of 28 of the circular bones. 2001. Mesonychid dentition consisted of molars modified to generate vertical shear, thin blade-like lower molars, and carnassial notches, but no true carnassials. Journal of Vertebrate Paleontology 26:355-370. Its limbs indicate a cursorial lifestyle [Charles Knight's Mesonyx shown below]. One particular ankle bone, the astragalus, had the potential to settle the debate. 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. As in most land mammals, the nose was situated at the tip of the snout. Then, in 2001, J.G.M. Posted by ; dollar general supplier application; These earliest cetaceans were not like the whales we know today, and only recently have paleontologists been able to recognize them. We are part of Science 2.0,a science education nonprofit operating under Section 501(c)(3) of the Internal Revenue Code. It was about the size of a large sea lion. There is a grain of truth in the cat versus dog question. There was rapturous applause, swooning, the delight of millions. Given that the hippopotamus is the closest living relative of cetaceans, Pakicetus and hippos may have inherited this behavior from their common ancestor. ScienceBlogs is where scientists communicate directly with the public. 133-161. Nearly all mesonychids are, on average, larger than most of the Paleocene and Eocene creodonts and miacoid carnivorans. For another, more detailed, article about Mesonychidae, see, Creative Commons Attribution-ShareAlike License. Let's back up a bit, though, and take a look at normal matter first. By continuing to use the website, you consent to analytics tracking per NYIT's Privacy Statement 1988, the feature they thought united Andrewsarchus and Cetacea (they include a cladogram with a list of synapomorphies for each node (or at least for many)) was arrangement of incisors in a fore-and-aft line: early whales (and I'm not sure how many really early Cetaceans were known when they wrote) have all three incisors in a line, Andrewsarchus has M3 behind rather than beside M2, which they saw as an intermediate step towards the Cetacean condition. Contributions are fully tax-deductible. All rights reserved. The molars were laterally compressed and often blunt and were probably used for shearing meat or crushing bones. However, the limb bones are quite dense, a trait that aquatic animals use to keep from floating to the surface. 1993. The offender this time is Nick Saunders of the University of Bristol, writing in Current World Archaeology #62 (Dec/Jan, available on Academia.edu). Technically speaking, the term "mesonychid" refers specifically only to the members of the family Mesonychidae, such as the species of the genus Mesonyx. Huxley thought thatBasilosaurusat least represented the type of animal that linked whales to their terrestrial ancestors. Dissacus was a jackal-sized predator that has been found all over the Northern Hemisphere, 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. One genus, Dissacus, had successfully spread to Europe and North America by the early Paleocene. The early representatives of these groups appeared about 33 million years ago and ultimately gave rise to forms as diverse as the Yangtze River dolphin and the gigantic blue whale. 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 fared very poorly at the close of the Eocene epoch, with only one genus, Mongolestes,[6] surviving into the Early Oligocene epoch.
The House of the Lord Christian Church