DISCOVERY OF THE TITANOTHERES AND ORIGINAL DESCRIPTIONS 



201 



SECTION 3. ORIGINAL DESCRIPTIONS OF TYPES OF 

 OLIGOCENE TITANOTHERES 



IIST OF GENERA AND SPECIES 



The following list shows that 49 species of Oligocene 

 titanotheres in North America and Europe have been 

 described and made the types of 17 different genera, 

 of which seven are regarded as valid. The types come 

 from many geologic levels. In finally determining the 

 genera wo are reluctantly compelled to adopt Menodus 



Pomel in preference to Titanotherium Leidy, to adopt 

 Megacerops Leidy although it is based on a poor type, 

 and to reject Symhorodon Cope, because the genotype 

 species belongs to Menodus. The genera that rest on 

 the genotypic specimens are Brontotherium Marsh and 

 Brontops Marsh. Diplacodon Marsh is the least 

 soundly determined. It is close to Brontops and may 

 represent a sport. Teleodus Marsh represents an in- 

 ferior stage of the Brontops phylum, transitional to 

 Protitanotherium. 



Chronologic list of the genera and species of Oligocene titanotheres 



[Generic names accepted in this work as valid are printed in small capitals; abandoned names are inclosed in brackets.] 



Present determination 



["Gigantic Palaeotheri- 

 um."] 



Menodus 



Menodus 



[Palaeotherium(?)] 



giganteus. 

 proutii 



[Titanotheriu m] 



[ Palaeothieriu m] 



[Rhinoceros] 



[Eotherium.] (Type Rhi- 

 noceros americanus 

 Leidy.) 



[Palaeotherium] 



[Leidyotherium] 



Megacerops 



Megacerops 



Brontotherium 



Brontotherium 



[Symborodon] 



[Symborodon] 



[Miobasileus] 



[ Miobasileus] 



Megaceratops 



[ Megaceratops] 



[Symborodon] 



[Symborodon] 



[Symborodon] 



[Brontotherium] 



[Symborodon] 



[ Anisacodon] 



[Anisaoodon] 



[Diconodon (not Anisa- 

 codon).] 



[Menodus] 



[ Menodus] 



[maximum], 

 [americanus] 



[giganteum]. 



coloradensis. 

 gigas 



torvus. 



[ophryas] 



acer 



heloceras 



bucco 



[altirostris] . _ 

 trigonoceras- 



[ingens] 



hypoceras 



[montanus]. 



angustigenis. 

 tichoceras 



[Menodus]- 

 [Menodus]_ 



dolichoceras _ 

 platyceras 



101959 



Brontops 



Brontops 



Brontops 



[M'enops] 



[Menops] 



[Titanops] 



[Titanops] 



[Titanops] 



Allops 



—29— VOL 1 16 



robustus- 

 dispar 



curtus.. 

 [elatus]_ 



Prout- 



Pomel _ 

 do_ 



Owen, Norwood, and 

 Evans. 



Leidy 



do 



_do_ 

 -do. 



do_ 



Prout_. 

 Leidy- . 



do_ 



Marsh. 

 do_ 



Cope.- 

 do. 



.do_ 

 .do. 

 _do. 



.do. 

 _do. 

 .do_ 



do. 



Marsh. 

 Cope.- 

 Marsh. 



do. 



do. 



Cope 



Scott and Osborn. 



.do. 



Marsh. 



do. 



do. 



.do. 

 .do. 

 .do. 



.do. 

 -do. 

 .do. 



Menodus Pomel. 



Do. 



Menodus giganteus Pomel. 

 Menodus proutii (Owen, Norwood, 

 and Evans). 

 Do. 

 (Indeterminate.) 



Do. 

 Subfamily Menodontinae, genus in- 

 determinate. 



(Indeterminate.) 



Do. 

 Megacerops Leidy. 

 Megacerops coloradensis Leidy. 

 Brontotherium Marsh. 

 Brontotherium gigas Marsh. 

 Menodus Pomel. 

 Menodus torvus (Cope). 

 (Indeterminate.) 



Do. 

 Megacerops acer Cope. 

 Menodus heloceras (Cope). 

 Megacerops bucco (Cope). 

 Megacerops acer Cope. 

 Menodus trigonoceras (Cope). 

 Menodus giganteus Pomel. 

 Brontotherium hypoceras (Cope). 

 (Indeterminate.) 

 Menodus giganteus Pomel. 

 Menodus giganteus? Pomel. 



?Brontops angustigenis (Cope). 

 Brontotherium tichoceras (Scott and 



Osborn) . 

 Brontotherium dolichoceras (Scott 



and Osborn). 

 Brontotherium platyceras (Scott and 



Osborn) . 

 Brontops Marsh. 

 Brontops robustus Marsh. 

 Brontops dispar Marsh. 

 Menodus Pomel. 

 Menodus varians (Marsh). 

 Brontotherium Marsh. 

 Brontotherium curtum (Marsh). 

 Brontotherium gigas Marsh. 

 Allops Marsh. 



