After McKenna & Bell, 1997, and Foss, 2007
<==o †Helohyidae Marsh, 1877
|?- †Bunodentus [not recognized by Foss (2007)]
|?- †Poeprodon [not recognized by Foss (2007)]
|?- †Apriculus [Protelotherium] [not recognized by Foss (2007)]
|?- †Ithygrammodon [not recognized by Foss (2007)]
|?- †Lophiohys [not recognized by Foss (2007)]
|?- †Pakkokuhyus [not recognized by Foss (2007)]
|-- †Parahyus vagus Marsh, 1876
|-- †Simojovelhyus pocitosense Ferrusquía-Villafranca, 2006
|-- †Dyscritochoerus lapointensis Gazin, 1956 [has been treated as an entelodontid]
|--o †Achaenodon Cope, 1873
| |-- †A. insolens Cope, 1873
| |-- †A. robustus Osborn, 1883
| |-- †A. uintense Osborn, 1895
| `-- †A. fremdi Lucas et al., 2004
`--o †Helohyus Marsh, 1872
|-- †H. lentus (Marsh, 1871)
|-- †H. plicodon Marsh, 1872
|?- †H. sp. [Stucky, 1998]
|?- †H. valitus (Marsh, 1872) [not recognized by Foss (2007)]
`?- †H. milleri Sinclair, 1914 [not recognized by Foss (2007)]
Reference(s):
- Carroll, R. L., 1988: Vertebrate paleontology and evolution.
–W. H. Freeman and company, New York, 1988, 698.
- Carroll, R. L., 1988: Appendix. 594-648.
in Carroll, R. L., 1988: Vertebrate paleontology and evolution.
–W. H. Freeman and company, New York, 1988, 698.
- Foss, S. E., 2007: Family Helohyidae. 85-88.
in Prothero, D. R. & Foss, S. E., (eds.) 2007: The evolution of artiodactyls.
–The Johns Hopkins University Press, Baltimore, 2007, xii-367
- Gazin, C. L., 1976: Mammalian faunal zones of the Bridger Middle Eocene.
–Smithsonian Contributions to Paleobiology: No. 26, pp. iv-25
- McKenna, M. C. & Bell, S. K., (eds.) 1997: Classification of mammals – above the species level.
–Columbia University Press, New York, 1997, xii-631
- Métais, G., Qi, T., Guo, J. & Beard, K. C., 2005: A new bunoselenodont artiodactyl from the Middle Eocene of China and the early record of selenodont artiodactyls in Asia.
–Journal of Vertebrate Paleontology: Vol. 25, #4, pp. 994-997