Opinions from B. J. Mader 1998
- 'Allops is a subjective synonym of Menops'
- 'Allops crassicornis is recombined as Menops crassicornis'
- 'Allops serotinus is recombined as Menops serotinus'
- 'Allops walcotti is recombined as Menops walcotti'
- 'Anisacodon montanus is a nomen dubium'
- 'Brontops belongs to Brontotheridae'
- 'Brontops dispar belongs to Brontops'
- 'Brontops robustus belongs to Brontops'
- 'Brontops validus is a subjective synonym of Brontops dispar'
- 'Brontotheriinae belongs to Brontotheridae'
- 'Brontotherium is a nomen dubium'
- 'Brontotherium gigas is a nomen dubium'
- 'Brontotherium hatcheri is recombined as Megacerops hatcheri'
- 'Brontotherium ingens is a nomen dubium'
- 'Brontotherium leidyi is a nomen dubium'
- 'Canis marshii is a subjective synonym of Palaeosyops paludosus'
- 'Diconodon is a nomen dubium'
- 'Diploclonus is a subjective synonym of Brontops'
- 'Diploclonus amplus is recombined as Brontops amplus'
- 'Dolichorhinae belongs to Brontotheridae'
- 'Dolichorhinus is a subjective synonym of Sphenocoelus'
- 'Dolichorhinus belongs to Brontotheridae' according to Hatcher 1895
- 'Dolichorhinus fluminalis is a subjective synonym of Sphenocoelus intermedius'
- 'Dolichorhinus heterodon is a subjective synonym of Sphenocoelus intermedius'
- 'Dolichorhinus heterodon belongs to Dolichorhinus' according to Douglass 1909
- 'Dolichorhinus intermedius is recombined as Sphenocoelus intermedius'
- 'Dolichorhinus longiceps is a subjective synonym of Sphenocoelus hyognathus'
- 'Dolichorhinus longiceps belongs to Dolichorhinus' according to Douglass 1909
- 'Duchesneodus belongs to Brontotheriinae'
- 'Eometarhinus is a subjective synonym of Palaeosyops'
- 'Eometarhinus huerfanensis is a subjective synonym of Palaeosyops fontinalis'
- 'Eotitanops belongs to Brontotheridae'
- 'Eotitanops gregoryi belongs to Eotitanops'
- 'Eotitanops gregoryi is a subjective synonym of Palaeosyops borealis' according to Wallace 1980
- 'Eotitanops gregoryi belongs to Eotitanops' according to Osborn 1913
- 'Eotitanops major is a subjective synonym of Eotitanops borealis'
- 'Eotitanops major belongs to Eotitanops' according to Osborn 1913
- 'Eotitanops princeps is a subjective synonym of Eotitanops borealis'
- 'Eotitanops princeps belongs to Eotitanops' according to Osborn 1913
- 'Heterotitanops is a nomen dubium'
- 'Heterotitanops parvus is a nomen dubium'
- 'Lambdotherium belongs to Perissodactyla'
- 'Lambdotherium brownianum is a subjective synonym of Eotitanops borealis'
- 'Limnohyops is a subjective synonym of Palaeosyops'
- 'Limnohyops matthewi is a subjective synonym of Palaeosyops paludosus'
- 'Limnohyops monoconus is a subjective synonym of Palaeosyops paludosus'
- 'Limnohyops priscus is a subjective synonym of Palaeosyops paludosus'
- 'Limnohyus is a subjective synonym of Palaeosyops'
- 'Limnohyus laevidens is a subjective synonym of Palaeosyops paludosus'
- 'Limnohyus robustus is recombined as Palaeosyops robustus'
- 'Megaceratops is a nomen dubium'
- 'Megaceratops acer is a nomen dubium'
- 'Megaceratops helocerus is recombined as Menops heloceras'
- 'Megacerops belongs to Brontotheridae'
- 'Megacerops assiniboiensis is a nomen dubium'
- 'Megacerops bicornutus is recombined as Brontops bicornutus'
- 'Megacerops brachycephalus is recombined as Brontops brachycephalus'
- 'Megacerops marshi is recombined as Menops marshi'
- 'Megacerops riggsi is a nomen dubium'
- 'Megacerops tyleri is recombined as Brontops tyleri'
- 'Menodus bakeri is recombined as Menops bakeri'
- 'Menodus dolichoceras is a nomen dubium'
- 'Menodus peltoceras is a subjective synonym of Megacerops curtus'
- 'Menodus platyceras is recombined as Megacerops platyceras'
- 'Menodus selwynianus is recombined as Brontops selwynianus'
- 'Menodus tichoceras is a nomen dubium'
- 'Menops belongs to Brontotheridae'
- 'Menops varians belongs to Menops'
- 'Mesatirhinus belongs to Dolichorhinae'
- 'Mesatirhinus petersoni is a subjective synonym of Mesatirhinus megarhinus'
- 'Mesatirhinus superior is a subjective synonym of Sphenocoelus intermedius'
- 'Metarhinus belongs to Dolichorhinae'
- 'Metarhinus riparius is a subjective synonym of Metarhinus fluviatilis'
- 'Notiotitanops belongs to Brontotheridae'
- 'Palaeosyopinae belongs to Brontotheridae'
- 'Palaeosyops belongs to Palaeosyopinae'
- 'Palaeosyops borealis is recombined as Eotitanops borealis'
- 'Palaeosyops copei is a subjective synonym of Palaeosyops robustus'
- 'Palaeosyops diaconus is a subjective synonym of Palaeosyops robustus'
- 'Palaeosyops fontinalis belongs to Palaeosyops'
- 'Palaeosyops grangeri is a subjective synonym of Palaeosyops robustus'
- 'Palaeosyops humilis is a subjective synonym of Palaeosyops paludosus'
- 'Palaeosyops hyognathus is recombined as Sphenocoelus hyognathus'
- 'Palaeosyops junior is a nomen dubium'
- 'Palaeosyops leidyi is a subjective synonym of Palaeosyops robustus'
- 'Palaeosyops longirostris is a subjective synonym of Palaeosyops paludosus'
- 'Palaeosyops major is a subjective synonym of Palaeosyops paludosus'
- 'Palaeosyops megarhinus is recombined as Mesatirhinus megarhinus'
- 'Palaeosyops paludosus belongs to Palaeosyops'
- 'Menodus is a nomen dubium'
- 'Palaeotherium giganteum is a nomen dubium'
- 'Palaeotherium proutii is a nomen dubium'
- 'Protitanops belongs to Brontotheriinae'
- 'Rhadinorhinus is a subjective synonym of Metarhinus'
- 'Rhadinorhinus abbotti is a subjective synonym of Metarhinus diploconus'
- 'Sphenocoelus belongs to Dolichorhinae'
- 'Symborodon is a nomen dubium'
- 'Symborodon altirostris is a nomen dubium'
- 'Symborodon bucco is a nomen dubium'
- 'Symborodon copei is a nomen dubium'
- 'Symborodon hypoceras is a nomen dubium'
- 'Symborodon torvus is a nomen dubium'
- 'Symborodon trigonoceras is recombined as Menops trigonoceras'
- 'Tanyorhinus is a subjective synonym of Sphenocoelus'
- 'Tanyorhinus blairi is recombined as Sphenocoelus blairi'
- 'Tanyorhinus bridgeri is recombined as Sphenocoelus bridgeri'
- 'Tanyorhinus harundivorax is recombined as Sphenocoelus harundivorax'
- 'Telmatherium belongs to Brontotheriinae'
- 'Telmatherium incisivum is recombined as Sthenodectes incisivum'
- 'Telmatotherium cornutum is a subjective synonym of Sphenocoelus hyognathus'
- 'Telmatotherium diploconum is recombined as Metarhinus diploconus'
- 'Titanops is a subjective synonym of Megacerops'
- 'Titanops curtus is recombined as Megacerops curtus'
- 'Titanops elatus is a nomen dubium'
- 'Titanops medius is a nomen dubium'
- 'Titanotheriidae is a subjective synonym of Brontotheridae'
- 'Titanotherium is a nomen dubium'