EVOLUTION OF THE SKELETON OF EOCENE AND OLIGOCENE TITANOTHERES 

 Chief skeletal characters of the Oligocene phyla 



663 



Brontops phylum 



AUops phylum 



Menodus phylum 



Brontotherium phylum 



Progressively graviportal, bra- 

 chypodal. Scapula and pel- 

 vis less broad than in Bronto- 

 therium. Tall and ponderous 

 animals. 



Relatively small, 

 short-limbed. 



Relatively long, slender- 

 limbed. Scapula and 

 pelvis of high, slender 

 type. Neck relatively 

 long. 



Progressively increasing in size and weight. 

 Skulls very large. Necks relatively short 

 and massive. Scapula and pelvis ex- 

 tremely broad, graviportal type. Limbs 

 very broad and massive. Feet relatively 

 short as compared with Menodus. 



STceletons and parts of skeletons of Oligocene titanotheres here described " 



« In addition to those listed there are two well-mounted skeletons of titanotheres (Metiacerops acer) in the Colorado Museum of Natural History, Denver, Colo. C1928). 

 (See PI. CCXXXVI.) 



