from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Hyracotherium.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Extinct early Eocene mammal, Hyracotherium leporinum
from the GNU version of the Collaborative International Dictionary of English
- n. an extinct primitive dog-sized 4-toed Eocene mammal, the earliest horse known in the line of descent of the modern horse. It is classed in the extinct genus Hydracotherium. Called also dawn horse.
from The Century Dictionary and Cyclopedia
- n. A genus of Eocene horses, representing the oldest known type of the family Equidæ, founded by Marsh (1876) upon remains from the coryphodon-beds of the Lower Eocene of New Mexico, indicating a kind of horse about as large as a fox, with four toes and a half on each fore foot, all incased in horn and forming hoofs, and three hoofed toes on each hind foot.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. earliest horse; extinct primitive dog-sized four-toed Eocene animal
The Valley somehow has various beasties from pre-history including the eohippus and the allosaurus.
Unlike gastornids the ones you always see in kids books flogging the dead eohippus, phorusrhacids had runner's legs.
But a new class of horse stepped forward, shouldering its way between a sturdy Morgan and a deerlike eohippus.
He had put that together with the discovery that common chickens and other creatures could be regressed to their saurian ancestors'the pioneering work had already been done on the eohippus and aurochs-and had seen a goldmine waiting for both the zoos and GenTech.
And so they taught the whole -- the dinosaurs, and we went and looked at Yale, they had the eohippus, the little horse evolving into the big horse, and all of that.
"Paleohippus, " of the many capacities, eohippus of the subtle form, merychippus with the horse-like appearance, pliohippus with the single hoof'these attributes persisted; there were dozens of other variations equally interesting which died out because they did not contribute to the final form.
But the thing that marked eohippus and made one suspect that this family of animals might be headed in some important direction was the feet.
But what gained greatest attention, especially from ranchers in the west, was his discovery in subsequent years of handsome skeletons of four of the progenitors of the horse: eohippus, mesohippus, miohippus and the crucial, determinative merychippus.
This year, in Pleistocene clay beds I myself found the jaw of an eohippus; it shone in my hand like a little jewel, and just north of Chalk Cliff, in a classic Morrison deposit, I had the thrill of finding an entire armored collar that triceratops carried about his neck, erecting it into a formidable defense whenever some predator attacked.
The dinosaurs were destined to disappear from earth, while this little animal would survive, its descendants and collaterals populating the entire world, first with prehistoric mammals themselves destined to extinction'titanotheres, mastodons, eohippus-and subsequently with animals man would know, such as the mammoth, the lion, the elephant, the bison and the horse.