. Elements of geology : a text-book for colleges and for the general reader. Geology. Fig. 751.—Stegosaurus stenops, x J (after Marsh). end, and must have been very formidable weapons of offense. The dis- parity in size of hind and fore limbs (Fig. 749), greater than in any known Dinosaur, shows that they walked habitually on the hind-legs, like the Ornithopoda. Like them, also, they probably had three to four toes on the hind - feet. The brains of all Juras- sic Dinosaurs were very small in com- parison with living reptiles, but this was especially true of Stegosaurs. To make up for this defi
. Elements of geology : a text-book for colleges and for the general reader. Geology. Fig. 751.—Stegosaurus stenops, x J (after Marsh). end, and must have been very formidable weapons of offense. The dis- parity in size of hind and fore limbs (Fig. 749), greater than in any known Dinosaur, shows that they walked habitually on the hind-legs, like the Ornithopoda. Like them, also, they probably had three to four toes on the hind - feet. The brains of all Juras- sic Dinosaurs were very small in com- parison with living reptiles, but this was especially true of Stegosaurs. To make up for this deficiency they had an enormous enlargement of the spinal cord in the sacral region. This sacral brain—if we may so call it—was ten times bigger than the cran- ial brain (Fig. 750). It was necessary in order to work the powerful hind-legs and tail. Ichthyosaurs.—Besides the Dinosaurs, Marsh describes from the same formation (Jurassic), but from a lower horizon, an Ichthyosau- rian, but differing entirely from the Ichthyosaurus of the European Jurassic in being toothless. On this account he calls the genus Bap- tanodon. This reptile had six digits in both fore and hind feet—a new and most remarkable feature (Fig. 752). Birds.—In 1881 Marsh discovered in the same beds, the Atlanto- saur beds of Wyoming, a Jurassic bird (Laopteryx), the only one yet known in America. It was undoubtedly a reptilian bird, probably with UO°Ooo-T Fig. 752.—Left hind paddle of Baptanodon discus (after Marsh), seen from below. One eighth natural size: f. femur; t, tibia; i, interme- dium; /', fibula; /, first digit; V, fifth 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 LeConte, Joseph, 1823-1901. New York : D. Appleton and Co.
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1892
