CENOZOIC ERA: AGE OF MAMMALS 



593 



acters except their heavy build, but before the extinction of the 

 race, some of them (Eobasileus) not only took on greater bulk, 

 attaining elephantine proportions, but also developed a peculiar 

 head (Fig. 536), the most conspicuous features of which were the 

 three pairs of knobs, or horns, and the long, saberlike teeth (canines) 

 which projected several inches below the upper jaw. One pair of 

 the knobs was situated on the nose, a larger pair over the eyes, and 

 the third pair above the ears at the back of the skull. It is not 

 known whether the protuberances were covered with horn or with 

 callous skin, but it was probably the latter. The use to which the 

 long, saberlike (canine) teeth, possessed by both males and females, 

 were put is not definitely known, but it seems probable that they 

 were used to pull down 

 branches from the trees, 

 and that the leaves were 

 then stripped off into the 

 mouth by a rapid side 

 motion of the head. 

 The brain was smaller in 

 proportion to the bulk 

 of the animal than in 

 any other mammal, liv- 

 ing or extinct, an animal 

 weighing two tons hav- 

 ing a brain no larger 

 than that of a dog. 

 Moreover, the brain was smooth, and a large proportion of it was 

 formed of the lobes of smell (olfactory). These animals seem to 

 have reached the climax of brute mass as compared with brain 

 power on the mammalian stem, and are to be compared with the 

 massive, small-brained dinosaurs of the reptilian stem. At certain 

 times they were very abundant, as is shown by the fact that two 

 hundred more or less complete skeletons have been collected by one 

 museum alone. 



The Lower Eocene amblypods were simpler in some particulars 

 than the later ones, being smaller and hornless, with shorter canine 

 teeth, although the grinding teeth differed very slightly from those 

 of their massive descendants. In other words, aside from increase 

 in size and the ornamentation of the skull, the evolution of the race 

 was slight. 



Fig. 536. — The most highly specialized of the am- 

 blypods, Eobasileus (Upper Eocene). (After Professor 

 Osborn.) 



