EARLIER PLIOCENE EPOCH 175 



consisted of the shortening of the neck (in consequence of 

 which the animal, when standing, could not get its head to 

 the ground) ; the great reduction of the scaffolding under-jaw ; 

 the verticalising of the sloping face ; and the development 

 of the trunk into a powerful grasping organ, with free play 

 in all directions. Mastodons, however, were not elephants 

 as strictly defined ; for the teeth of elephants, although 

 ridged, are not " nippled." Mastodons differed also from 

 true elephants, as did the earlier long-chinned forms, in 

 having their tusks partly banded with enamel. 



In certain districts some of the proboscideans possessed 

 teeth that had undergone further modifications. The ridges 

 were sharply defined into gable shapes ; and the name of 

 " roof tooth " has accordingly been bestowed on these 

 animals (Stegodori). The bosses or nipples had disappeared ; 

 and the spaces between the ridges were beginning to be filled 

 with some of the inner tooth substance known as dentine, 

 modified into a cement. The teeth thus resembled very 

 closely those of modern elephants. The tusks, moreover, 

 were no longer enamelled ; and the animals may fairly be 

 regarded as having passed out of the Mastodon stage and 

 become true elephants. 



Even these were not the most advanced of the trunked 

 animals on India's scenes. Other elephants were munching 

 their food with teeth still more modified (E. planifrons, 

 Euelephas). Their teeth, in fact, were of a quite modern 

 character very deeply ridged, with the interspaces filled 

 up with cement. The teeth thus had rough though fairly 

 level surfaces, and were excellently adapted for grinding 

 purposes. As after events proved, elephants toothed in this 

 manner were alone destined to survive. Teeth, it need 

 hardly be said, have been an important factor in mammal 

 fortunes. 



Horses in vast numbers were on the plains and hill-sides. HORSES 

 Most of them were identical in form with those that were 

 living in Europe at this time three-toed animals about the 

 size of Shetland ponies, and with grinding teeth of inferior 

 construction to those of modern horses (Hipparion). Evolu- 

 tion, however, in India had proceeded farther ; for animals 



