The Riverside Natural History Volume 5

The Riverside Natural History Volume 5

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1888 edition. Excerpt: ...toes are thus, taken singly, not symmetrical, while taken together they form a symmetrical pair. Compared with the Perissodactyla the Artiodactyla have fewer trunk vertebne, almost always nineteen; the number of those that bear ribs differs much in different forms. The complexity of the stomach, and the smaller length of the caecum are further points of contrast with the Perissodactyla, which we shall have the opportunity of elucidating further on. Reference has already been made to the likelihood of the Artiodactyla and Perissodactyla having descended from a common stock, and also to the peculiarities of foot and tooth-structure which living and fossil Artiodactyla exhibit. If before proceeding to discuss the living representatives of this order, we first review the fossil forms from the standpoint indicated, we shall find the crescent-toothed forms greatly predominate in point of numbers over those with tubercular teeth. Of the latter only the pigs and hippopotami survive to represent the extinct Palceochcerus and Chcerotherium, while certain other tubercular-toothed forms in which the foot-structure was reduced on the inadaptive plan (vide p. 234) have left no successors. Such was the two-toed Entelodon of the early miocene period. Again, among the crescent-toothed forms the same phenomenon reappears. The inadaptive way of reduction was first adopted and led from four-toed forms like Bothriodon, Dichobune, and Hyopotamus of eocene strata, to the cloven-footed Anoplotherium, Xiphodon, and Diplocus of miocene strata. These, however, left no descendants. They were as richly developed in their characteristic period as the ruminants at the present day, for some small forms of Hyopotamus are known as small as a rabbit, others, more

Product details

  • Paperback | 258 pages
  • 189 x 246 x 14mm | 467g
  • United States
  • English
  • black & white illustrations
  • 1236840186
  • 9781236840189