LOXOLOPHODON AND UINTATHERI UM. 



43 



premaxillaries above, points to the fact that the animal fed close to the ground, 

 but the projecting snout would have prevented his cropping the grass. It is 

 probable that the head could reach within a foot or two of the ground. The 

 limb-bones as a whole mdicate a less muscular animal than either the rhinoceros 

 or the elephant 



Anatomy, Muscles and Brain. The muscles at the back of the neck were 

 stout in order to raise the much elongated head. The brain-cavity, which Marsh 

 called attention to at an early date, is situated between the posterior protuber- 

 ances and indicates a brain so small that it could have been readily pulled through 

 the neural arches of the vertebrae. The forward extension of the head beyond the 

 brain region is enormous. It was accompanied by the development of large sinu- 

 ses in the sphenoidal and ethmoidal regions. The solid appearance of the skull 

 exterior is rather deceptive, the anterior nares being very large and the nasals 

 excavated on their lower sides. The protuberances are solid above, but 

 hollow at their bases. Altogether the skull was, like that of the elephant, much 

 lighter than it appears at first sight. 



The rounded upper crest of the occiput is swollen for the attachment of the 

 sterno-cleido-mastoid, the complexus and rectus-capitis muscles. From the ver- 

 tical ridge dividing the occiput in the median line rose the powerful ligamenUim 

 tiuchce, which was attached to the spines of the cervicals and anterior dorsals. 

 These muscles and ligaments probably filled completely the space behind the occi- 

 put. The inner angle of the jaw is roughened for the attachment of the ptery- 

 goid muscles ; these were inserted in the large pterygoid bones above, and were 

 employed in grinding the food. The large temporal fossa and stout zygomatic 

 arch gave origin to the temporal and masseter muscles. The lower jaw, although 

 undersized, must have had considerable power. Above the orbits in Uintathe- 

 rium are strong ridges for the muscles of the eyebrow and scalp. The tips 

 of the nasals in the same genus are deeply pitted for the levator labii and other 

 muscles of the lip. The animal did not need a proboscis ; the indications point 

 to a stout prehensile upper lip like that of the tapir. This would have been of 

 use in bending the reeds and grasses so that they could be cropped ofE by the 

 sharp lower incisors. 



Taken altogether, the long body, wide thorax, and comparatively short 

 limbs with spreading toes indicate an animal rather of the habits of the 

 Rhinoceros than of the Elephant. The lighter limbs indicate some speed. For 

 many reasons it is improbable that the frontal and parietal protuberances 

 bore horns. In many of the genera they are wider at the top than at the base. 

 Their bony structure differs from that of true horn-cores. Horns upon the 

 parietal processes would have been useless for purposes of defence. The 



