R. S. Lull —Dinosaurian Distribution. 29 



not older than Cenomanian time, and, with the exception of 

 the questionable Maorourosaurus of the English Cenomanian 

 and the Titanosaurus reported by Deperet (vide supra) from 

 the Danian of Southern France, the contained dinosaurs repre- 

 sent by far the latest appearance of the Sauropod group any- 

 where recorded on the face of the globe. 



The last stand of these huge creatures, so far as our present 

 knowledge goes, and again excepting Deperet's Titanosaurus 

 (vide supra, p. 26), was in Patagonia, where the remains of 

 three genera, Titanosaurus, Argyrosaurus and the small 

 aberrant Microsaurus are found in the Guaranitic beds corre- 

 lated by Hatcher (1900, p. 95) with the Laramie (Danian) of 

 North America. 



Orthopoda. 



Geographically the Orthopoda (figs. 6 and 7) as a whole, 

 with the exception of the Ceratopsia, which are apparently 

 confined to western North America, have a common distribu- 

 tion; and, while paralleling that of the other dinosaurs in the 

 northern hemisphere, are unique in their entire absence from 

 the southern. It can hardly be said that the paucity of our 

 records is responsible for this apparent lack of southern forms, 

 for their preservation and discovery should surely have brought 

 some to light when the Theropoda and Sauropoda are relatively 

 so abondant. 



America seems to have been the original home of the 

 orthopod dinosaurs, the first recorded type the bones of which 

 are known being Nanosaurus of the Jura-Trias of Utah. In the 

 upper series of the Newark (Rhsetic) beds in Massachusetts, 

 Connecticut and New Jersey are indications of numerous species 

 of these plant-feeding forms, so that it is evident that by the 

 beginning of Jurassic time not only were they widespread in 

 N"orth America but they had reached a considerable degree of 

 variation as well, implying a long though unrecorded career. 

 During the Jurassic the record is again a blank as with the 

 American Theropoda, but with the ushering in of Lower 

 Cretaceous time by the great Morrison deposits in the West 

 and the Potomac in the East we find a marvelous assemblage 

 of types, small and large, armored and unarmored. This is 

 especially true in the West, since the Potomac dinosaurs, coming 

 as they do from few localities which are all of one character, 

 reflect the Sauropod rather than the Orthopod habitat, so that 

 while an armored dinosaur, Priconodon, and an unarmored 

 Dryosaurus (Lull 1910) only have been found in Mary- 

 land, others doubtless existed and may some day be brought to 

 light. 



All through Upper Cretaceous time the American record is 

 quite complete, especially in the West, though New Jersey, 



