. The chain of life in geological time [microform] : a sketch of the origin and succession of animals and plants. Paleontology; Paleobotany; Paléontologie; Paléobotanique. 2l8 THE CHAIN OF LIFE. of the modern horse. A very similar genus {Orohippus)^ lacking only the fifth rudimentary toe, replaces Eohippus in the Middle Eocene. Mesohippus of the Lower Miocene is as large as a sheep, and has only three toes on the fore-foot and a splint bone, while its teeth assume a more equine character (Fig. 17b). In the Upper Miocene Miohippus continues the line, while Protohippus of the Lower Pliocene is s
. The chain of life in geological time [microform] : a sketch of the origin and succession of animals and plants. Paleontology; Paleobotany; Paléontologie; Paléobotanique. 2l8 THE CHAIN OF LIFE. of the modern horse. A very similar genus {Orohippus)^ lacking only the fifth rudimentary toe, replaces Eohippus in the Middle Eocene. Mesohippus of the Lower Miocene is as large as a sheep, and has only three toes on the fore-foot and a splint bone, while its teeth assume a more equine character (Fig. 17b). In the Upper Miocene Miohippus continues the line, while Protohippus of the Lower Pliocene is still more equine and as large as an ass, and corresponds with the European Hipparion in having the middle toe of each foot alone long enough to reach the ground. In the Upper Pliocene true horses appear with only a single toe, and splint bones instead of the others. In America, though the horse was. Fig. 176.—Series of Equine Feet.—After Marsh. a, Orohifipus, Eocene, b, Miohippus, Miocene, c, Protohippus, Lower Pliocene. d, Pliohippus, Upper Pliocene, e, Equus, Post-Pliocene and Modern. unknown at the time of the discovery of the continent, several species occur in the Tertiary and Post-Pliocene, showing that the genus existed there up to a comparatively late period; and when re-introduced it has thriven and run wild in the more temperate regions. What cause could have led to its extinction in Post-Glacial times is as yet a mystery. This genealogy of the horse, independently of its evolutionist application, is very interesting. It shows that some Eocene types were suited to continuance, and even adapted for extension, while others were destined to become altogether extinct at an early date. It shows farther that the power of continuance resided not so much in the gigantic and prominent species as in smaller. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illust
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectpaleontology, bookyea
