. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. HISTORY OF MAEINE MAMMALS ABEL. 483 this is connected the joeculiar marine turtles, which were modified for living entirely in the sea, and possessed a long salamander-like body and fins, and a vertical caudal fin like the ichthyosaur. They ally themselves to the snake-like mosasaurs (fig. 10), which again exhibit other forms of body. ..^im^^B ^ ^\Y\\\^'^. SERss^ ^\\\'A^'' Fig. 10.—Restored skeletons of Mosasaurus from the Upper Chalk of Ka
. Annual report of the Board of Regents of the Smithsonian Institution. Smithsonian Institution; Smithsonian Institution. Archives; Discoveries in science. HISTORY OF MAEINE MAMMALS ABEL. 483 this is connected the joeculiar marine turtles, which were modified for living entirely in the sea, and possessed a long salamander-like body and fins, and a vertical caudal fin like the ichthyosaur. They ally themselves to the snake-like mosasaurs (fig. 10), which again exhibit other forms of body. ..^im^^B ^ ^\Y\\\^'^. SERss^ ^\\\'A^'' Fig. 10.—Restored skeletons of Mosasaurus from the Upper Chalk of Kansas. A. Clidastes velox Marsh. Length about 4 meters (12 feet). B. Platecarpus coryphaeus Cope. Length about meters (14 feet). C. Tylosaurus prorlger Cope. Length about meters (23 feet). After S. W. Willlston. Of all the marine reptiles, none can be the ancestor of the marine mammals. Without excej^tion, all these marauders of the sea were reiDresentatives of separate branches of the reptile stock, which have entirely died out. The time of the extinction of the great marine reptiles does not coincide with that of the appearance of the marine mammals. One may not at all picture to himself that the extirpation of the marine reptiles which ruled the sea at the end of the Mesozoic was due to their, being supplanted and annihilated by the rising and flourish- ing mammals. A long time elapsed between the destruction of the marine reptiles and the appearance of the first marine mammals. III. The Ancestors or the Marine Mammals. The Mesozoic is the time of the uncontested dominion of the reptiles on land, in the air, and in the sea. The mammals of this epoch are known only from very rare and insufficient remains. The dominion of the mammals begins with that division of geological time which we call the early dawn of the world, eojs x"-'-^-) or the Eocene. They first conquer the land and then take possession of the Please note that these images are extracted from s
Size: 4101px × 609px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorsmithsonianinstitutio, bookcentury1800, bookdecade1840
