mammifères

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 View Book Page: Book Viewer About This Book: Catalog Entry View All Images: All Images From Book Click here to view book online to see this illustration in context in a browseable online version of this book. Text Appearing Before Image: served and very complete skeletons ofdifferent species of ichthyosaurs from the Jurassic deposits ofWiirtemberg, in which remains of these animals occur in great 112 WATER REPTILES OF THE PAST AND PRESENT profusion. His researches, and those of several authors since then,supplementing and confirming or disproving those of the manyobservers made during the preceding seventy years, have finallydetermined almost perfectly the complete structure of the moretypical ichthyosaurs, enabling us to infer not a little as to theirhabits and distribution in the old Jurassic oceans. Within thepast few years the discoveries of Professor J. C. Merriam of Cali-fornia have likewise added greatly to our knowledge of the earlierichthyosaurs. It may now truthfully be said that of no group ofextinct reptiles do we have a more complete and satisfactory knowl-edge than of the ichthyosaurs. Nevertheless we have yet very much more to learn about theorder Ichthyosauria as a whole—whence they came and how they Text Appearing After Image: Fig. 52.—Ichthyosaurus quadricissus.museum, from Dr. Dreverman. Photograph of specimen in Senckenberg originated; what their nearest kin were among other reptiles; andespecially, more about the connecting links between them andterrestrial reptiles. They have, as an order, so isolated a position,are so widely separated from all other reptiles in structure, that theyhave long been a puzzle to paleontologists. Like the whales andother cetaceans among mammals, we know the ichthyosaurs wellin the plenitude of their power and the fulness of their development,but have yet only an imperfect knowledge of their earlier history,and none whatever of their earliest. However, as will be seenfarther on, the recent discoveries by Merriam have shed much lighton some of the stages of their evolution. So nearly perfectly wereall the later ichthyosaurs adapted to their life in the water that itwas believed by nearly all paleontologists until about a score of years ICHTHYOSAURIA 3 ago that they had desc Note About Images Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.