| 词条 | Eohippus |
| 释义 |
| fossil_range = {{fossil range|Ypresian}} | image = Hyracotherium Eohippus hharder.jpg | image_caption = Reproduction of a painting {{circa|1920}} | genus = Eohippus | parent_authority = Marsh, 1876 | species = angustidens | authority = (Cope, 1875) | synonyms =
}}Eohippus is an extinct genus of small equid ungulates.[1] The only species is E. angustidens, which was long considered a species of Hyracotherium. Its remains have been identified in North America and date to the Early Eocene (Ypresian) stage.[2] DiscoveryIn 1876, Othniel C. Marsh described a skeleton as Eohippus validus, from the Greek ἠώς (eōs, "dawn") and ἵππος (hippos, "horse"), meaning "dawn horse". Its similarities with fossils described by Richard Owen were formally pointed out in a 1932 paper by Sir Clive Forster Cooper. E. validus was moved to the genus Hyracotherium, which had priority as the name for the genus, with Eohippus becoming a junior synonym of that genus. Hyracotherium was recently found to be a paraphyletic group of species, and the genus now includes only H. leporinum. E. validus was found to be identical to an earlier-named species, Hyracotherium angustidens (Cope, 1875), and the resulting binomial is thus Eohippus angustidens. Common misconception on sizeIn most early books about mammal evolution,{{which|date=November 2017}} Eohippus is described as being "the size of a small Fox Terrier",{{ambiguous|date=November 2017}} even though in real life Eohippus was probably the size of a larger dog breed such as a Labrador retriever{{cn|date=November 2018}}. This arcane analogy was so curious that Stephen Jay Gould wrote an essay about it ("The Case of the Creeping Fox Terrier Clone", essay #10 in his book, Bully for Brontosaurus), in which he concluded that Henry Fairfield Osborn had so described it in a widely distributed pamphlet. The reasons for this comparison are unclear, but Gould posits that Osborn, a keen fox hunter, could have made a natural association between horses and the dogs that accompany them.[3] See also
References1. ^{{Cite journal | last1 = MacFadden | first1 = B. J. | title = Fossil Horses--Evidence for Evolution | doi = 10.1126/science.1105458 | journal = Science | volume = 307 | issue = 5716 | pages = 1728–1730 | date = March 18, 2005 | pmid = 15774746| pmc = }} {{Equidae extinct nav}}{{Taxonbar|from=Q5241216}}2. ^{{Cite journal | last1 = Froehlich | first1 = D. J. | title = Quo vadis eohippus? The systematics and taxonomy of the early Eocene equids (Perissodactyla) | doi = 10.1046/j.1096-3642.2002.00005.x | journal = Zoological Journal of the Linnean Society | volume = 134 | issue = 2 | pages = 141–256 | year = 2002 | pmid = | pmc = }} 3. ^Gould, S.J. (1991). Bully for Brontosaurus: Reflections in Natural History, W. W. Norton & Co., 540pp. 4 : Eocene horses|Eocene odd-toed ungulates|Eocene mammals of North America|Prehistoric mammal genera |
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