7 8 EVOLUTION IN THE PAST 



South Africa, India, and North America. These strange 

 creatures had well-developed hind-limbs ; whilst their " arms" 

 were comparatively short. The latter, no doubt, were 

 chiefly used for seizing and holding prey ; and locomotion 

 was effected, somewhat in kangaroo fashion, on the hind- 

 limbs only. Facility for agile and speedy movement was 

 certainly afforded by the hollowness of the limb-bones 

 (Zanclodon, Euscelosaurus, Epicampodori). The animals 

 varied a good deal in size : some remarkable forms, with 

 bird-like skulls, must have stood between five and six feet 

 in height (Anchisaums). 



The precise line of dinosaurian descent is unknown. All 

 the Triassic forms seem to have been carnivorous ; and 

 they haunted, no doubt, lake-banks and riversides ; and 

 victimised the tender and neglected offspring of amphibians 

 and also of fellow-reptiles. 



Dinosaurs, so far as is known, were the first bipeds to 

 appear on earth the first creatures to stand and move 

 about in a fairly erect position. They come, in fact, within 

 Plato's special definition of a man " a biped without 

 feathers." Dinosaurs, therefore, were not dreamt of in his 

 philosophy. 



PLESIO- Other reptiles, now first in view and known as plesio- 



SAURIANS saurians, betrayed no inclination to bipedalism ; and when 

 on land must have moved about in a somewhat laboured 

 manner. They were undoubtedly good swimmers, and when 

 afloat must have had an appearance such as swans, deprived 

 of feathers and suffering from stiff necks, would present. 

 They had probably descended from some forms that had been 

 more or less permanent land-dwellers. Possibly their remote 

 ancestors were some land-frequenting stegocephs of Car- 

 boniferous times. Terrestrial life, it would seem, had lost its 

 charm ; and these Triassic descendants were experimenting 

 in water, and possibly becoming experts in fishing. Many 

 of them were of small size ; but here and there creatures 

 were to be seen varying in length from four to six feet 

 (Lariosaurus, Nothosaurus). 



Plesiosaurians were much more developed in the next 

 Period : and it is interesting to note that these Triassic 



