No. 502] HABITS OF SAUROPODOUS DINOSAURS 673 



readily; that they walked mostly on all fours; that to 

 some extent at least they went about on land ; that their 

 food was mainly, if not wholly, vegetable ; and that they 

 had imperfect or no means of chewing it. 



We are assisted in understanding the habits of these 

 creatures by a knowledge of the nature of their environ- 

 ment. And this we must determine from the character 

 of the deposits in which their bones are discovered and 

 from the kinds of animals and plants accompanying 

 them. Investigation has shown that their remains occur 

 in sandstones and clays which were certainly laid down 

 in fresh waters having no great amount of motion. The 

 accompanying animals are other dinosaurs, some herbiv- 

 orous, others carnivorous; besides crocodiles, turtles, 

 freshwater fishes and freshwater shells. Some of the 

 plants that occur in the deposits certainly lived in fresh 

 water. 



Hatcher 1 has discussed at length the nature of the 

 region in which the species of Diplodocus and their allies 

 lived, as well as the habits of the Sauropoda in general; 

 and the present writer agrees with him on most points. 

 Hatcher believed that the Atlantosaurus beds were de- 

 posited, not in an immense freshwater lake, as held by 

 some geologists, but over a comparatively low and level 

 plane, which was occupied by perhaps small lakes con- 

 nected by an interlacing system of river channels. The 

 climate was warm and the region was overspread by lux- 

 uriant forests and broad savannas. The area thus oc- 

 cupied included large parts of the present states of Colo- 

 rado, New Mexico, Utah, Montana, and the Dakotas. In 

 his memoir on Diplodocus, Hatcher 2 compares the condi- 

 tions prevailing in that region during the Upper Jurassic 

 to those now found about the mouth of the Amazon and 

 over some of the more elevated plains of western Brazil. 

 In such regions the rivers, fed from distant elevated 

 lands, must have been subject to frequent inundations. 



l Mem. Carnegie M%8., II, 1903, pp. 54-67. 

 3 Mem. Carnegie Mus., I, p. 60. 



