File:The dinosaur book - the ruling reptiles and their relatives (1951) (20212405588).jpg

Title: The dinosaur book : the ruling reptiles and their relatives
Identifier: bookruli00colb (find matches)
Year: 1951 (1950s)
Authors: Colbert, Edwin H. (Edwin Harris), 1905-2001; Knight, Charles Robert, 1874-1953; American Museum of Natural History
Subjects: Dinosaurs; Reptiles, Fossil
Publisher: New York : Published for the American Museum of Natural History by McGraw-Hill
Contributing Library: American Museum of Natural History Library
Digitizing Sponsor: IMLS / LSTA / METRO

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very broad, robust bodies and strong, heavy legs, and as in other primitive anapsids there was no clearly defined neck. The last of the cotylosaurs, living through Triassic times, were diadectomorphs which were smaller than the large Diadectes of North America and the massive pariasaurs of Europe and Africa. Their development ran counter to the earlier trend towards giantism in this branch of the cotylosaurian reptiles. Known as procolophonids after the charac- teristic genus Procolophon (pro-KOL-o-fon), these animals evidently ranged widely throughout the world in Triassic times, since they are found in South Africa, central Europe, Scotland, and North America. An early type of procolophonid is to be found in the Lower Triassic genus, Procolophon, of South Africa. Although small, Procolophon was robustly con- structed. It had a deep skull, narrow in the front and broad at the back. The pineal opening on the top of the skull was very large. The teeth were limited in number, and those in the back portion of both upper and lower jaws were somewhat broadened for chopping or cutting green plant food. In Lower Triassic times the procolo- phonids appeared also in central Europe where they had become specialized to the ex- tent that in some of them there were spikes on the sides or the back of the skull. Finally, the Middle Triassic of Scotland and the Upper Triassic of New Jersey yielded the most highly specialized procolophonids, the last of the cotylosaurs. They were charac- terized by a flattening of the skull and an ex- cessive development of the spikes on the sides and the back of the head. As in the other diadectomorphs, the pineal "eye" was large. The teeth had become far fewer but were highly specialized, for the back teeth were broad, sharp chisels, evidently use- ful for chopping and cutting food. A particularly fine specimen is the almost complete skeleton of Hypsognathus (hips- og-NATH-us), recently discovered near Passaic, New Jersey, and now in the Ameri- can Museum of Natural History. With the passing of the procolophonids, during the late stages of Triassic history, the cotylosaurs became extinct. They had lived out their evolutionary life span—they had to give way to the more highly de- veloped reptiles of later Mesozoic times. Such were the beginnings of the reptiles. Let us now follow their interesting evolution through its many ramifications. A LARGE PARIASAUR, Scutosaurus, from the Permian beds of Russia, showing an early trend to giantism in the reptiles. This animal was as large as an ox and perhaps heavier, but it retained a primitive form. Notice the pro- portionately small head, the out-bowed legs, and the clumsy body Restoration by John C. Germann
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