226 DINOSAURS OF NORTH AMERICA. 



DISTRIBUTION OF ORNITHOPODA. 



The great group which the author has called the Ornithopoda is 

 well represented in Europe by Iguanodou and its allies. The remark- 

 able discoveries in the Wealden of Belgium of a score or more skele- 

 tons of Iguanodou have furnished material for an accurate study of 

 the genus which they represent, and, indirectly, of the family. The 

 genus Iguanodou, founded by Mantell in 1824, is now the best known 

 of European forms, while Hypsilophodon Huxley, 1870, also from the 

 Wealden, is well represented, and its most important characters are 

 fully determined. For comparison with American forms, restorations 

 of both Hypsilophodon and Iguanodou are given on Pis. LXXXIII and 

 LXXXIV. The other genera of this group, among which are Mochlodon 

 Bunzel, 1871, Vectisaurus Hulke, 1879, and Sphenospondylus Seeley, 

 1883, are described from less perfect material, and further discoveries 

 must decide their distinctive characters. 



None of these genera are known from America, but allied forms are 

 not wanting. A distinct family, the Trachodontkhe, is especially abun- 

 dant in the Cretaceous, and another, the Camptosaurida?, includes most 

 of the Jurassic species. The latter are the American representatives 

 of the Iguanodontida-. The nearest allied genera are, apparently, 

 Iguanodon and Camptosaurus for the larger forms, and Hypsilopho- 

 don and Laosaurus for those of small size. A few isolated teeth from 

 each country suggest th.it forms more nearly related may at any time 

 be brought to light. 



Many generic names have been proposed for members of this group 

 found in America and in Europe, but in most cases they are based on 

 fragmentary, detached specimens, which must await future discoveries 

 before they can be assigned to their true place in the order. 



In conclusion, it may be said that the three great groups of Dinosauria 

 are each well represented in Europe as well as in America. Some of the 

 families, also, of each order have representatives in the two regions, 

 and future discoveries will doubtless prove that others occur in both. 



No genera common to the two continents are known with certainty, 

 although a few are so closely allied that they can not be distinguished 

 from one another by the fragmentary specimens that now represent them. 



From Asia and Africa, also, a few remains of dinosaurs have been 

 described, and the latter continent promises to yield many interesting 

 forms. Characteristic specimens, representing two genera, one appar- 

 ently belonging to the Stegosauria, and one to the Theropoda, are 

 already known from South Africa, from the region so rich in other 

 extinct Reptilia. 



From Australia no Dinosauria, except a single specimen, have as 

 yet been recorded, but many more will undoubtedly be found there, as 

 reptiles of this great group were the dominant land animals of the 

 earth during all Mesozoic time. 



