Hyopsodontidae

Hyopsodus and Mioclaenidae

Hyopsodus, the namesake of Hyopsodontidae, is the most well-understood member of the family, with extensive fossils of the entire body. In many ways, it is also the most aberrant. It was a small Eocene omnivore with a weasel-like build, combining a long body with short legs and sensitive smell and hearing.

It is unclear whether Hyopsodus has any close relation to most other "hyopsodontids". Some studies prefer to use the family Mioclaenidae when referring to non-Hyopsodus members of the group, most of which lived in the Paleocene. Other studies refer to the entire group as hyopsodontids. Before the discovery of an Orthaspidotherium skull, the Pleuraspidotheriidae were included as Mioclaenids.

• Asiohyopsodus Tong and Wang, 2006
• Bomburodon Williamson and Carr, 2012 (formerly Bomburia Van Valen, 1978)
• Bubogonia Johnston and Fox, 1984
• Chacomylus Williamson and Weil, 2011
• Choeroclaenus Simpson, 1937
• Ellipsodon Scott, 1892
• Hyopsodus Leidy, 1870
• Lessnessina? Hooker, 1979 (possibly a paenungulate instead)
• Litaletes Simpson, 1935
• Mioclaenus Cope, 1881
• Promioclaenus Trouessart, 1904
• Protoselene Matthew, 1897
• Obtususdon? Xu, 1977
• Tiznatzinia Simpson, 1936
• Valenia de Muizon and Ciffeli, 2000

Apheliscidae

Apheliscidae is a group of small "condylarths", sometimes classified as a subgroup of hyopsodontids (generally to the exclusion of mioclaenids). Limb fossils indicate that Apheliscus and Haplomylus are adapted for fast and agile movement, unlike Hyopsodus. Many aspects of their teeth and limb bones suggest that apheliscids are closely related to Macroscelidea (the living elephant shrews or sengis, an entirely African order in the present day). Some studies regard these similarities as mere convergence. While most apheliscids are North American, Louisininae is an exclusively European group. A few studies raise it to a family (Louisinidae) separate from Apheliscidae, though still rather closely related.

• Aletodon Gingerich, 1977
• Dorraletes Gingerich, 1983
• Haplaletes Simpson, 1935
• Haplomylus Matthew, 1915
• Litomylus Simpson, 1935
• Utemylus Gingerich, 1983
• Apheliscinae Matthew, 1918
  • Apheliscus Cope, 1875
  • Gingerichia Zack et al., 2005
  • Phenacodaptes Jepsen, 1930
• Louisininae Sudre and Russell, 1982 (= Louisinidae)
  • Berrulestes Hooker and Russell, 2012
  • Cingulodon? De Bast and Smith, 2017
  • Dipavali Van Valen, 1978
  • Gigarton Hooker and Russell, 2012
  • Louisina Russell, 1964
  • Monshyus Sudre and Russell, 1982
  • Paschatherium Russell, 1964
  • Prolouisina Hooker and Russell, 2012
  • Teilhardimys Kretzoi and Kretzoi, 2000 (formerly Microhyus Teilhard de Chardin, 1927)
  • Thryptodon Hooker and Russell, 2012
  • Walbeckodon Hooker and Russell, 2012

Kollpaniinae

Kollpaniinae (or Kollpaniidae) is a group of small South American mammals often considered close to South American native ungulates (SANUs, a.k.a. Meridiungulata). Some studies have argued that kollpaniines originated from North American mioclaenids. In parsimony analyses by Püschel et al. (2024), the kollpaniines Molinodus and Tiuclaenus were found to be closely related to Mioclaenus turgidus, but this close relation was not recovered by the same study's Bayesian analyses.

There is still a distinct possibility that mioclaenids are ancestral to SANUs as a whole, since many studies have found similarities between Northern Hemisphere "condylarths" (such as mioclaenids and phenacodontids) and certain SANU groups (such as didolodontids and litopterns).

• Andinodus de Muizon and Marshall, 1987
• Escribania? Bonaparte et al., 1993 (potentially a didolodontid instead)
• Molinodus de Muizon and Marshall, 1987
• Pascualodus? Gelfo, 2004
• Pucanodus de Muizon and Marshall, 1991
• Simoclaenus de Muizon and Ciffeli, 2000
• Tiuclaenus de Muizon and Marshall, 1987

Tricuspiodontinae

• Paratricuspiodon
• Tricuspiodon