Principal Forms of the Dinosauria. 329 



There is some evidence, from footprints, at least, that, in 

 America, the order was represented in the Trias. 



Theuopod a. 



The carnivorous Dinosauria have all been included, by the 

 author, in one order, Theropoda, although there are two or 

 three suborders quite distinct from each other. This great 

 group is well represented both in Europe and America in the 

 Trias, is especially abundant in the Jurassic, and diminishes in 

 the Cretaceous, at the close of which, it apparently becomes 

 extinct. 



The typical genus is Megalosaurus, Buckland, 1824, the type 

 of which was the first Dinosaurian reptile described. Although 

 its remains are comparatively abundant in Europe, they have 

 been found only in a fragmentary condition, and many impor- 

 tant points in the structure of the skull and skeleton are still 

 in doubt. 



The oldest representatives of this group in Europe are 

 Thecodontosaurus, Riley and Stutchbnry, 1836, and Plateo- 

 saurus, von Meyer, 1837, both from the Trias. The former 

 genus is from the lower horizon, near Bristol, England ; the 

 latter, from the Keuper of Germany. Zanclodo?i, Plieninger, 

 1846, is from the same horizon as Plateosaurus, and appears 

 to be the same thing. Massospondylus, Owen, 1854, from the 

 Trias of South Africa, is apparently a form allied to Theco- 

 dontosaurus. The nearest American genus is Anchisaurus, 

 two species of which are known from the Connecticut River 

 sandstone. 



The most interesting member of the Theropoda known in 

 Europe is the diminutive specimen described by Wagner, in 

 1861, as Compsognathus longipes. The type specimen, the 

 only one known, is from the lithographic slates of Solenhofen, 

 Bavaria, and is now preserved in the museum in Munich. 

 Fortunately, the skull and nearly all the skeleton are preserved, 

 and as it has been studied by many anatomists, its more impor- 

 tant characters have been made out. It is regarded as repre- 

 senting a distinct suborder, and no nearly related forms are 

 known in Europe Its nearest ally is probably the specimen 

 from Colorado, described by the author, in 1881, as Hallopus 

 victor. This animal was about the same size as Compsognathus, 

 and resembles it in some important features. It is probably 

 from nearly the same geological horizon, but may be somewhat 

 older. Each of these specimens appears to be unique, and until 

 a careful comparison of the two is made, their relations to each 

 other can only be conjectured. 



The American representative of Megalosaurus is apparently 

 AUosaurus, a genus established by the author, in 1877. The 



