JURA-TRIAS IN AMERICA. 



463 



The Sauropoda were the hugest of all. They were jive-toed, plant i- 

 grade> and. quadrupedal. Their large, hollow limb-bones (Fig. 744) 



Fig. 747.— 1. Tooth of Laosaurus altus (after Marsh), front view. 2. The same, side view. Both 

 twice natural size. 3. Bones of the left hind-leg of Laosaurus altus (after Marsh). One eighth 

 natural size: il, ilium; te, ischium; p, pubis; p', post-pubic bone; /, femur; t, tibia; /', fibula; 

 a, astragalus; c, calcaneum; I, first metatarsal; IYmt, fourth metatarsal. 



and massive pelvis (Fig. 745) show that they walked with the body well 

 lifted from the ground (Fig. 746). They were probably herbivorous. 

 Good examples of these are seen in the Atlantosaurus (a thigh of which 

 was found more than eight feet long and twenty-five inches thick, the 

 animal itself being probably at least one hundred feet long) ; the 

 Brontosaurus, sixty feet long (Fig. 746) ; and the Morosaurus (Fig. 

 744, 745). 



