Principal characters of American Jurassic dinosaurs; Part VIII, The order Theropoda

THE carnivorous ])inosauria form a well marked order, which the writer has called the Theropoda, in his classification of this group.* Although much has beeu written' about these reptiles since Buckland described .Megalosaurus in 1824, but little has really beeu made out in regard to the structure of the skull, aud many portions of the skeleton stilI remain to be determinea. The fortunate discovery of two nearly perfect skeletons of this order, as well as a number of others with various important parts of the skeleton in good preservation, has afforded the writer an opportunity to investigate the group, and some of the resl1lts are here presented. A more detailed description of these fossils, and others allied to them, will be given in another communication. Of the carnivorous Dinosaurs from the American Jurassic, there are four genera, which each represents, apparently, a distinct family. These genera are Allosaurus, O(l3lurus, Laorosaurus, and the new genus Oeratosauru,s, here described. In the present article, AllosauJ'us and Oe'l'atosaul'us will be mainly used to illustrate the more important characters of the order, and the relations of the other genera to them will be indicated in the classification presented in conclusion.