2l6 



THE ORIGIN AND EVOLUTION OF LIFE 



PLATEOSAURUS 



which enables these animals to feed practically in the same 

 manner as the raptorial birds. 



Herbivorous Dinosaurs, Sauropoda 



As analyzed by Lull along the lines of modern interpreta- 

 tion, beside the small carnivorous dinosaurs there may be 



traced in the Connecticut 

 Triassic footprints the be- 

 ginnings of an herbivorous 

 offshoot of the primitive 

 carnivorous dinosaur stock, 

 leading into the elephantine 

 types of herbivorous dino- 

 saurs known as the Sauro- 

 poda, which were first 

 brought to our knowledge 

 in this country through the 

 pioneer studies of Marsh 

 and Cope. 



As there is never any 

 need of haste in the capture 

 of plant life these animals 

 underwent a reversed evo- 

 lution of the limbs from the 

 swift-moving primitive bi- 

 pedal type into a secon- 

 dary slow-moving quadru- 

 pedal ambulatory type. 

 The original power of occa- 

 sionally raising the body 

 on the hind limbs was «Jtil] retained in some of these gigantic 

 forms. The half-way stage between the bipedal and the 



ANCHISAURUS 



Fig. 94. Analogy Between the Carnivo- 

 rous Anchisaunis Type of the Triassic 

 AND the Ancestral Herbivorous Sauro- 

 POD Type Platcosaiirus. 



The upper restoration (Plalcosaurus) repre- 

 sents a bipedal stage of sauropod evolution 

 which was discovered in the German Trias, 

 in which the transition from carnivorous to 

 herbivorous habits is observed. Recent 

 discovery renders it probable that the 

 herbivorous Sauropoda descend from carniv- 

 orous ancestors like Anchisaunis. 



Restoration of Plaleosaurus modified from Jae- 

 kel. Restoration of Anchisaurus after Lull. 



