Age: 46-47 million years ago, Eocene Epoch. Biomolecular and genetic studies repeatedly found that whales were most closely related to the group of hoofed mammals called artiodactyls, particularly hippos. New fossil discoveries have now revealed several of the critical evolutionary steps in the earliest history of whales. Famous Did Mesonychids Swim References. Known locations for Zygorhiza is almost exclusively the East coast of the United States, primarily in the Gulf Coast states, and many fossils have been found in Louisiana, Mississippi, and Alabama. Since mammals only get two sets of teeth a milk set, which is shed, and a permanent adult set their feeding choices and strategies leave distinctive wear patterns on their teeth which can be examined for clues. A. Balkema, 1986), 91. A fossil skull was found in Pakistan in river sediments near an ancient sea. In order to investigate these mysteries, scientists turn to indirect evidence preserved on and inside the teeth themselves. were essentially contemporaries. published in 1976. However, even though they are similar in appearance to land animals, some consider Mesonychids to be ancestors of whales. 2 (1995): 402. What did mesonychids evolve into? - Shabupc.com these genera for ancestor of the archaeocetes, and thus mesonychids S. jiashanensis was discovered in Anhui province, China (, paleocoordinates ), in the Tuijinshan The extinct suborder Archaeoceti is a 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. They had powerful jaws, and their teeth, as previously mentioned, were similar to whales teeth. monthName[7] = 'August' of Osborn and Earle). Skeletons of terrestrial cetaceans and the relationship of whales to artiodactyls Nature, 413 (6853), 277-281 DOI: 10.1038/35095005, Van Valen, Leigh. that they form an actual lineage of ancestors and descendants. [34], In addition, no chain of descent from archaeocetes to modern It could also hunt in the sea, probably swimming by kicking its big feet. the vast differences. 9 Views. Cetacea includes the whales, porpoises, and dolphins. Mitochondrial Genes, Molecular Biology and Evolution 11, no. (Mammalia: Condylarthra), Journal of Paleontology 54, no. ends, broken lines, and question marks. The hind feet of ambulocetus, however, were clearly adapted for swimming.10 The Eocene; Oldest Mammals Exploring Fossil from www.georgiasfossils.comFunctional analysis of its skeleton shows. Gingerich, et al., (1994): 844-845. descended from protocetids, evolutionists claim it is transitional [5] In other words, Szalay concluded that both Dissacus and What this means, Thewissen and collaborators hypothesize, is that Indohyus was chewing in the same way that the early whales did despite having a significantly different diet. As Dr. Gould noted in his review of recent whale research, the next important discovery was the first complete hind limbs of a fossil whale, Basilosaurus isis, which lived 5 million to 10 million years after Pakicetus. In order to gauge the timing of this major event as well as investigate how early whale diets changed the researchers carried out an in-depth dental exam on several of the creatures. [RETURNTOTEXT], [34] Fordyce and Barnes, 420, 431. Basilosaurus isis, on the other Perhaps the whale was tackling larger prey with bigger, harder bones, or perhaps the difference is an indication that the whale had a more varied diet then its cousins. It is within the family Mesonychidae, and cladistic analysis of a skull of Sinonyx jiashanensis identifies its closest relative as Ankalagon.
