Opinions from G. F. Gunnell and V. L. Yarborough 2000
- 'Canis marshii is a subjective synonym of Palaeosyops paludosus'
- 'Eometarhinus is a subjective synonym of Palaeosyops'
- 'Eometarhinus huerfanensis is a subjective synonym of Palaeosyops fontinalis'
- 'Eotitanops gregoryi is a subjective synonym of Eotitanops borealis'
- 'Eotitanops major is a subjective synonym of Eotitanops borealis'
- 'Eotitanops minimus belongs to Eotitanops'
- 'Eotitanops princeps is a subjective synonym of Eotitanops borealis'
- '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 laevidens'
- 'Limnohyops priscus is a subjective synonym of Palaeosyops laevidens'
- 'Limnohyus is a subjective synonym of Palaeosyops'
- 'Limnohyus laevidens is recombined as Palaeosyops laevidens' according to Trouessart 1898
- 'Limnohyus laevidens is recombined as Palaeosyops laevidens' according to Roger 1896
- 'Limnohyus laevidens is recombined as Palaeosyops laevidens' according to Earle 1892
- 'Limnohyus laevidens is recombined as Palaeosyops laevidens' according to Cope 1884
- 'Limnohyus laevidens is recombined as Palaeosyops laevidens'
- 'Limnohyus laticeps is recombined as Palaeosyops laticeps'
- 'Limnohyus robustus is recombined as Palaeosyops robustus'
- '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 robustus'
- 'Palaeosyops junior is a subjective synonym of Palaeosyops paludosus'
- '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 paludosus belongs to Palaeosyops'