File:Gastrolith sample.jpg

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Summary

DescriptionGastrolith sample.jpg	English: Text Appearing Before Image: agazines a few years ago depicted one ofthem with the neck coiled like the body of a snake. One notedpaleontologist, indeed, not many years ago described the plesiosaursas resting on the bottom in shallow waters with the neck upliftedabove the surface viewing the waterscape! And when we con-sider the fact that some species of the elasmosaurs had a neck notless than twenty feet in length, such a flexible use of it would notseem improbable. But the plesiosaurs did not and could not usethe neck in such ways. They swam with the neck and head, how-ever long, directed in front, and freedom of movement was restrictedalmost wholly to the anterior part. The posterior part of the neckwas thick and heavy, and could not have been moved upward ordownward to any considerable extent and not very much laterally. 92 WATER REPTILES OF THE PAST AND PRESENT From all of which it seems evident that the plesiosaurs caught theirprey by downward and lateral motions of their neck, rather thanby quick swimming. Text Appearing After Image: Fig. 43.—Gastroliths and bones of an undetermined plesiosaur from the LowerCretaceous of Kansas. About thirty years ago, the late Professor Seeley, a well-knownEnglish paleontologist who devoted much attention to the studyof these reptiles, found with the remains of a medium-sized plesio-saur nearly a peck of smoothly polished, rounded, and siliceous SAUROPTERYGIA 93 pebbles. He believed that their occurrence with the skeleton wasnot accidental, but that they had been intentionally swallowedby the animal when alive, and formed at its death a part of itsstomach contents. Even earlier than this the same habit had beennoticed. Nearly at the same time that Seeley mentioned thepeculiar discovery he had made the present writer found severalspecimens of plesiosaurs in the chalk of western Kansas with whichsimilar pebbles were associated, an account of which was givensoon afterward by the late Professor Mudge. Since then numerouslike discoveries have made it certain that the plesiosaurs usu
Date	1914
Source	Water reptiles of the past and present
Author	Williston, Samuel Wendell, 1851-1918

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