Geology . , and rarely forwalking, the animals pose being facilitated by hollow bones. The headwas relatively large, an unusual character for a race among which smallheads and diminutive brains were the fashion of the day. Not allthe theropods, however, were gigantic; there were small leaping forms,like Compsognathus, not larger than a rabbit. The herbivorous dinosaurs (Stegosauria, Sauropoda, Ornithopoda1)first became known in this system, but their development was so ex- 1 For monographic treatment see Dinosaurs of North America, 0. C. Marsh, 10thAnn. Rept., II. S. Gecl. i-uirv. The three su
Geology . , and rarely forwalking, the animals pose being facilitated by hollow bones. The headwas relatively large, an unusual character for a race among which smallheads and diminutive brains were the fashion of the day. Not allthe theropods, however, were gigantic; there were small leaping forms,like Compsognathus, not larger than a rabbit. The herbivorous dinosaurs (Stegosauria, Sauropoda, Ornithopoda1)first became known in this system, but their development was so ex- 1 For monographic treatment see Dinosaurs of North America, 0. C. Marsh, 10thAnn. Rept., II. S. Gecl. i-uirv. The three suborders there recognized are Theropoda,Sauropoda, and Precmtata, Ornithopoda and Stegosauria being regarded as divisions ofPredentata. 96 GEOLOGY. traordinary that they soon outranked the carnivorous forms both insize and diversity. The sauropoda were generally massive animals,with sub-equal limbs and the quadruped habit. Among these, Bronto-saurus (Apatosaurus) attained the extraordinary length of GO feet. Fig. 371.—A carnivorous dinosaur, Ceratosaurus nasicornis, about TV natual size, length about 17 feet; from the Como beds, Colorado. (Restoration of skele-ton by Marsh.) and possibly more, taking rank as one of the largest of known landanimals (Fig. 372). This enormous creature was characterized, never-theless, by weakness rather than strength. The general organizationwas unwieldy; the head was very small relatively, the brain havingless diameter than the spinal cord. The task of providing food forso large a body must have been a severe tax on so small a head. Theinconvenience of its bulkiness was perhaps relieved by an aquatichabit. From the fact that its skeleton is sometimes found in a nearlycomplete and orderly state, it has been inferred that the creature was notinfrequently the victim of its own massiveness, and lost its life bysinking in some soft, treacherous shoal. This colossal animal may betaken as illustrating the point at which bulk becomes a burden, andas
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