462 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



B i_^.XT/^XX:_/ A ic/^^\3 c 



Brontotherium (peltoceras) curtum ?q Brontotherium leidyi ?? Brontotherium curtum 



Figure 392. — Skulls of the brontotheriine group 



Top view. One-twelfth natural size. 



Subfamily Brontotheriinae: A, Broniotheriitm leidyi, a primitive stage with skull top long, small horns transversely oval at the tips, nasals 

 long and tapering, frontal region wide, zygomata not expanded; Chadron A. B, Brontotherium (peltoceras) curtum, skull top long but 

 zygomata arching widely, short massive horns confluent with the high connecting crest and pointed at the tips, nasals reduced and pointed. 

 C, Brontotherium curtum, a very large male skull with widely expanded zygomata, widely flaring flat-oval horn.s, very short nasals, wide 

 frontal region, occipital pillars widely expanded transversely. 



Subfamily Megaceropinae: D, Megacerops acer, skull short with widely expanded zygomata, horns cylindrical with but little connecting 

 crest, nasals short and wide, skull top wide with parallel edges. E, Megacerops bucco, 9; resembles in general the preceding type but 

 has larger horns. F, Megacerops bucco, J , a large animal with greatly expanded zygomata and rather feeble cylindrical horns. 



