260 



TIT.-USrOTHERES OP ANCIENT "WYOMING, DAKOTA, AND NEBRASKA 



Zygomatic-cephalic indices in the tiianotheres 

 [Arranged in chronologic and taxonomic order] 



Lower Eocene: 



Eotitanops borealis (dolichocephalic) 



Lambdotherium popoagicum (dolichocephalic) 



Middle Eocene: 



Limnohy ops monoconus (brachy cephalic) 



Limnohyops laticeps (brachycephalic) 



Palaeosyops leidyi (brachycephalic) 



Upper Eocene: 



Telmatherium ultimum (crushed) (mesaticephalic)- 



Sthenodectes incisivus (mesaticephalic) 



Manteoceras manteoceras (mesaticephalic) 



Mesatirhinus megarhinus (dolichocephalic) 



Mesatirhinus petersoni (dolichocephalic) 



Doliohorhinus superior (dolichocephalic) 



Dolichorhinus hyognathus (dolichocephalic) 



Metarhinus fluviatilis (dolichocephalic) 



Metarhinus earlei (dolichocephalic) 



Rhadinorhinus abbotti (dolichocephalic) 



Lower Oligocene: 



Brontops brachycephalus, 9 (mesaticephalic) 



Brontops brachycephalus, & (brachycephalic) 



Brontops validus (brachycephalic) 



Brontops robustus (brachycephalic) 



Allops marshi (mesaticephalic) 



Allops serotinus (brachycephalic) 



Diploclonus amplus (brachycephalic) 



Diploclonus tyleri (brachycephalic) 



Menodus giganteus (mesaticephalic) 



Menodus varians (brachycephalic) 



Menodus heloceras (brachycephalic) 



Megacerops coloradensis (brachycephalic) 



Megacerops acer (brachycephalic) 



Brontotherium leidyi (brachycephalic) 



Brontotherium gigas (brachycephalic) 



Brontotherium sp. div. (brachycephalic) 



Index 

 50 

 (?) 



72 

 75 



74-75 



61 



63-65 



63-68 



56-59 



49-52 



49 



46 



58 



59-63 



51-52 



64 



72 



85 



76-83 



64^69 



72-78 



91 



85 



62-70 



73 



79(?) 



76 



84 



66 



84 



74-80 



Generic tendencies. — Certain generic ascending series 

 are progressively brachycephalic — for example, Bron- 

 tops and Megacerops; others are progressively dolichoce- 

 phalic — for example, Menodus. 



Zygomatic-cephalic indices of the titanotheres and other 

 perissodactyls 



[Arranged in ascending numerical order] 



Dolichocephalic : 



Hyperdolichocephalic — Index 



Domestic horse (Equus caballus) 39, 40. 4^44. 1 



Dolichorhinus hyognathus (Eocene) 43-49 



White African rhinoceros (Ceratotherium 



simum) 43-50 



Domestic ass (Equus asinus) 46. 9-49. 9 



Indian tapir (Tapirus indicus) 47 



Mesatirhinus petersoni (Eocene) 49 



Dolichorhinus superior (Eocene) 49 



Eotitanops princeps (Eocene) 50 



Dolichocephalic — 



Mesatirhinus petersoni (Eocene) 51, 52 



Rhadinorhinus abbotti (Eocene).. 51-52, 53, 54, 54. 9 



Subdolichocephalic — 



Black African rhinoceros (Opsiceros bicornis) _ _ 56 



Mesatirhinus megacrhinus (Eocene) 56-57 



Metarhinus fluviatilis (Eocene) 58 



Metarhinus earlei (Eocene) 59 



Sumatran rhinoceros (Rhinoceros sumatrensis).. 59 



Mesaticephalic : index 



Telmatherium ultimum (Eocene) 61 



Metarhinus earlei (Eocene) 60. 1-61, 62-63 



Menodus giganteus (Oligocene) 62-70 



Sthenodectes incisivus (Eocene) 63-65 



Manteoceras manteoceras (Eocene) 63-68 



Allops marshi (Oligocene) 64-69 



Brontops brachycephalus, $ (Oligocene) 64 



Brontotherium leidyi (Oligocene) 66 



Menodus giganteus (Oligocene) 69. 9, 70 



Brachycephalic : 



Subbrachycephalic — 



Allops serotinus (Oligocene) 72 



Brontops brachycephalus, c? (Oligocene) 72 



Menops varians (Oligocene) 73 



Brontotherium curtum (Oligocene) 74 



Palaeosyops leidyi (Eocene) 74-77 



Limnohyops laticeps (Eocene) 75 



Brachycephalic — 



Megacerops? coloradensis (Oligocene) 76 



Brontotherium curtum (Oligocene) 78 



Allops crassicornis (Oligocene) 76 



Palaeosyops major (Eocene) 77 



Allops serotinus (Oligocene) 78 



Brontops dispar (Oligocene) 78-79 



Brontotherium platyceras (Oligocene) 80 



Brontotherium peltoceras (Oligocene) 80 



Brontotherium curtum, 9 (Oligocene) - 80 



Brontotherium gigas (Oligocene) 82, 84 



Brontops validus (Oligocene) 83 



Megacerops acer (Oligocene) 84 



Diploclonus tyleri (Oligocene) 85 



Hyperbrachycephalic — 



Brontotherium gigas (Oligocene) 87? 



Brontops dispar (Oligocene) 87 



Brontops robustus (Oligocene) 87? 



Diploclonus amplus (Oligocene) 91? 



DIFFERENCES IN TERMINOLOGY OF SKULL PROPORTIONS 

 IN TITANOTHERES AND MAN 



In the Oligocene genus Menodus the zygomatic- 

 cephalic index rises above 60, and the skuU is there- 

 fore "mesaticephalic," as defined above, rather than 

 "dolichocephalic," as described in the author's earlier 

 papers. The term "stenocephalic," meaning narrow 

 headed, may therefore be used to describe the narrow 

 cranium and dentition of Menodus, in contrast with 

 the wide and truly brachycephalic cranium and denti- 

 tion of Brontops, Megacerops, and Brontotherium. 



According to the indices adopted for all perisso- 

 dactyls, no Oligocene titanotheres are truly dolicho- 

 cephalic; all are mesaticephalic or brachycephalic as 

 compared with many Eocene titanotheres. The term 

 dolichocephalic, as used in the section on the Oligocene, 

 may be considered equivalent to "stenocephalic" (see 

 Chap. V) as applied to Oligocene titanotheres having 

 relatively narrow face and teeth but a zygomatic 

 index of 64-70. 



The terms given above are not used in the same sense 

 as in anthropology. The anthropologists for cranial 

 form should have introduced the terms "dolicho- 

 cranial" and "brachycranial," but as a matter of fact 

 they used "brachycephalic" and "dolichocephalic." 

 There is no other word left for craniometry, because 



