Eohippus + Eohomo.gif on:
[Wikipedia]
[Google]
[Amazon]
''Eohippus'' is an
In 1876,
extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
genus of small equid
Equidae (sometimes known as the horse family) is the taxonomic family of horses and related animals, including the extant horses, asses, and zebras, and many other species known only from fossils. All extant species are in the genus '' Equus'', w ...
ungulates. 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).
Discovery
In 1876, Othniel C. Marsh
Othniel Charles Marsh (October 29, 1831 – March 18, 1899) was an American professor of Paleontology in Yale College and President of the National Academy of Sciences. He was one of the preeminent scientists in the field of paleontology. Among h ...
described a skeleton as ''Eohippus validus'', from el, ἠώς (, 'dawn') and (, 'horse'), meaning 'dawn horse'. Its similarities with fossils described by Richard Owen
Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomist and paleontologist. Owen is generally considered to have been an outstanding naturalist with a remarkable gift for interpreting fossils.
Owe ...
were formally pointed out in a 1932 paper by Clive Forster Cooper
Sir Clive Forster Cooper, FRS (3 April 1880 – 23 August 1947) was an English palaeontologist and Director of the Cambridge University Museum of Zoology and Natural History Museum in London. He was the first to describe ''Paraceratherium'', als ...
. ''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
In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...
group of species, and the genus now includes only ''H. leporinum''. ''E. validus'' was found to be identical to an earlier-named species, ''Orohippus angustidens'' Cope, 1875, and the resulting binomial
Binomial may refer to:
In mathematics
*Binomial (polynomial), a polynomial with two terms
* Binomial coefficient, numbers appearing in the expansions of powers of binomials
*Binomial QMF, a perfect-reconstruction orthogonal wavelet decomposition
...
is thus ''Eohippus angustidens''.
Description
''Eohippus'' stood at about 12 in (30 cm), or 3 hands tall. It had 4 toes on its front feet and 3 toes on the hinds, each toe ending in a hoof. Its incisors, molars and premolars resemble modern ''Equus'', however a differentiating trait of ''Eohippus'' is its large canine teeth.Stephen Jay Gould comments
In his 1991 essay, "The Case of the Creeping Fox Terrier Clone",Stephen Jay Gould
Stephen Jay Gould (; September 10, 1941 – May 20, 2002) was an American paleontologist, evolutionary biologist, and historian of science. He was one of the most influential and widely read authors of popular science of his generation. Gould sp ...
lamented the prevalence of a much-repeated phrase to indicate ''Eohippus'' size ("the size of a small Fox Terrier"), even though most readers would be quite unfamiliar with that breed of dog. He concluded that the phrase had its origin in a widely-distributed pamphlet by Henry Fairfield Osborn, and proposed that Osborn, a keen fox hunter, could have made a natural association between his horses and the dogs that accompanied them. ''Eohippus'' was approximately high at the shoulder, which would be comparable to a Fox Terrier, which is up to high at the shoulder.
See also
*'' Mesohippus'' *''Protohippus
''Protohippus'' is an extinct three-toed genus of horse. It was roughly the size of a modern donkey. Fossil evidence suggests that it lived during the Late Miocene (Clarendonian to Hemphillian), from about 13.6 Ma to 5.3 Ma.
Analysis of ''Proto ...
''
References