MAMMALS OF PREHISTORIC TIMES 207 



been found in Illinois, and it is only through such evidence that 

 their former presence in this area is known. Teeth of two of 

 these prehistoric mammals, the mastodon and the mammoth, 

 are pictured in fig. 112. 



MEGALONYX JEFFERSONII Desmarest 



Giant Ground Sloth 



The most bizarre of all of the extinct mammals of the Illi- 

 nois region was the giant ground sloth, w T hich was nearly as 

 large as a present-day elephant, but looked somewhat like a 

 bear with a long neck and with a very broad, blunt tail. It ap- 

 parently fed on leaves and twigs. Since sloths of today live in 

 tropical America, it is usually assumed that the giant ground 

 sloth occurred in the Illinois region during the warm inter- 

 glacial periods.- There are few fossil records of this prehistoric 

 species for Illinois. 



CASTOROIDES OHIOENSIS Foster 



Giant Beaver 



A gigantic beaver, as large as a bear, once frequented the 

 waterways of the present-day Illinois area. One can surmise 

 that the giant beaver constructed enormous dams and was capa- 

 ble of felling large trees. It became extinct at the close of the 

 Ice Age. Several fossilized bones of this animal have been dis- 

 covered in Illinois. 



MAMMUT AMERICANUS (Kerr) 



American Mastodon 



The American mastodon, fig. 113, was about the size of an 

 average elephant of present-day India, but the body was cov- 

 ered with long, coarse hair. The upper tusks were more or 

 less parallel and either straight or curved upward. In the male, 

 a single, short lower tusk was present, presumably completely 

 concealed in the lower lip. The mastodon was probably a brow- 

 ser, feeding heavily upon leaves, for it lived in forested areas 

 and had teeth for grinding food, fig. 112. Remains of this spe- 

 cies have been found in a number of widely scattered localities 

 in Illinois. 



