LIFE 



Fitf. 438. Restoration of a Jurassic crocodilian, Geosaurus sucvicus. (Fraas.) 



but slightly from the land type, perhaps due to the recurring neces- 

 sity of visiting the shores for depositing and hatching eggs. Marine 

 turtles, so characteristic of the Cretaceous, had not yet appeared. 



Land Life 



Vegetation. The land vegetation of the Jurassic was little more 

 than a continuation and expansion of that of the late Triassic, with 

 slow progress toward living types. Cycads, conifers, ferns, and 

 e"quiseta were the leading plants, slightly more modernized than 

 their Triassic ancestors, but not changed radically. 1 The conifers 

 were represented by yews, cypresses, arborvitas, and pines, all of 

 which had a somewhat modern aspect, though all the species are 

 extinct. 



An interesting feature of the European record is the rather 

 frequent occurrence of land plants in marine beds, which implies 

 that many trunks, twigs, leaves, and fruits were floated out to sea, 

 and that the landward edges of the marine deposits have escaped 

 destruction. In the same beds are the remains of many land insects, 

 not a few of them being wood-eating beetles. 



Animals. Of the early Jurassic land faunas of North America 

 little is known; but in the Morrison beds (perhaps Comanchean, 

 p. 504) there is a fauna composed chiefly of dinosaurs. Some of these 

 reptiles were large, and some small, and the group as a whole had 

 great diversity in many directions. There were not only carniv- 

 orous types, which had appeared in the Trias, but numerous herbiv- 



I 1 Jurassic plants of the United States, with descriptions and illustrations by 

 Lester F. Ward; aoth Ann. Kept., U. S. Geol. Surv., pp. 334-430. 



