Image from page 222 of "Water reptiles of the past and present" (1914) (14772753062)

Identifier: waterreptilesofp1914will

Title: Water reptiles of the past and present

Year: 1914 (1910s)

Authors: Williston, Samuel Wendell, 1851-1918

Subjects: Aquatic reptiles

Publisher: Chicago, Ill., The University of Chicago Press

Contributing Library: Boston Public Library

Digitizing Sponsor: Boston Public Library

Text Appearing Before Image:

tus ofthe amphibious crocodiles, since all their prey must have beenwater-breathing creatures. Their eyes were directed laterally,not more or less upward, as in their nearest relatives. Nearly allother crocodiles have an opening through the hind end of the lower CROCODILIA 211 jaw, but the thalattosuchians did not. The teeth were about asnumerous as in the modern gavials, but they projected freely onlya short distance above the gums in life, and they were very slenderand sharply pointed, excellently well adapted for catching smoothand slippery fishes. Their vertebrae, like those of all other reptilesof their time, were biconcave. Those of the neck resembled thoseof the teleosaurs, save that there were only seven, fewer than is thecase with any other members of the order. In becoming adaptedto their peculiar mode of life these crocodiles lost two vertebraefrom the neck. All modern crocodiles have two ribs attached to thefirst vertebra; the thalattosaurs had but one, another evidence of

Text Appearing After Image:

Fig. 109.—Tail, scapula (sc), and coracoid (c) of Geosaurus. (After Fraas) primitive characters. While the number of vertebrae in the neckwas reduced, in the back it was increased to eighteen; all othercrocodiles have but fifteen or sixteen. The trunk was long, anotheradaptation to water life. There were two firmly united vertebraein the sacrum, as in the modern forms. The reason for the per-sistence of this terrestrial character we shall see later. The tail was very long and strong, nearly as long as all theremainder of the body, and relatively much longer than in othercrocodiles. It is of interest to observe that the head, neck, body,and tail had almost the same relative proportions as those of thegreat sea-lizards, the mosasaurs. The terminal bones of the tail 212 WATER REPTILES OF THE PAST AND PRESENT are very peculiar, and very different from the corresponding bonesof other crocodiles. While the spines of the tail bones along theanterior part are only moderately stout and long,

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Image from page 222 of "Water reptiles of the past and present" (1914)

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