File:Geology (1907) (14589653280).jpg

Identifier: geology00cham (find matches)
Title: Geology
Year: 1907 (1900s)
Authors: Chamberlin, Thomas C. (Thomas Chrowder), 1843-1928 Salisbury, Rollin D., 1859- joint author
Subjects: Geology
Publisher: New York, H. Holt and co.
Contributing Library: Internet Archive
Digitizing Sponsor: Internet Archive

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ich probably found much of their 1 Broom, The Geology of Cape Colony, by A. W. Rogers, 1905, p. 244. THE JURASSIC PERIOD. 101 food in the small mammals and reptiles frequenting the shores of theestuaries. Primitive lizards were doubtless abundant, but because of theirterrestrial habits and small size, very few if any have been discovered. The advent of aerial life; the pterosaurs.—It has already beennoted that the crowding of the land may have led some reptiles totake to the sea. The same influence may have forced others to taketo the air, and thereby escape the monsters of the swamps, jungles,and forests. Whatever the cause, the most unique feature of theperiod was the development of flying reptiles. Appearing at thevery close of the Trias in a few yet imperfectly known forms, theypresented themselves at the very opening of the Jurassic period (LowerLias), as fully developed flying animals in the genus Dimorphodon,and later formed a diversified group embracing long-tailed forms, as
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Fig. 374.—A flying saurian, Rhamphorhynchus phyllurus Marsh, in which the wingmembranes are preserved; about one-fourth natural size. The rod-like bonesthat support the wing membranes are the extended fifth phalanges; the caudaloar and the elongate skull are also well shown. From the lithographic stone atEichstadt, Bavaria. Rhamphorhynchus, and short-tailed forms, as Pterodaciylus. With littledoubt they sprang from some agile, hollow-boned saurian, more orless remotely akin to the slender, leaping dinosaurs. Between theponderous brontosaurs (Fig. 372) and the airy pterodactyls (Fig. 374),the Jurassic suarians present the strangest of contrasts. The Jurassicpterosaurs were small, but their successors attained a wing-spread ofnearly a score of feet. They were curiously composite in structureand adaptation. Their bones were hollow, their fore limbs modified 102 GEOLOGY. for flight, their heads bird-like, and their jaws sel with teeth; but tooth-less forms at length appeared. They were

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