Apheliscidae Matthew, 1918

Zack, Shawn P., Penkrot, Tonya A., Krause, David W. & Maas, Mary C., 2005, A new apheliscine “ condylarth ” mammal from the late Paleocene of Montana and Alberta and the phylogeny of “ hyopsodontids ”, Acta Palaeontologica Polonica 50 (4), pp. 809-830 : 811

Family Apheliscidae Matthew, 1918

Included taxa.— Apheliscinae Matthew, 1918 , Louisininae Sudre and Russell, 1982, Haplomylus Matthew, 1915 , Litomylus Simpson, 1935 , Haplaletes Simpson, 1935 , Aletodon Gingerich, 1977 , Dorraletes Gingerich, 1983 , Utemylus Gingerich, 1983 .

Revised diagnosis.—Apheliscids can be distinguished from similar taxa including hyopsodontids, pentacodontids, and basal erinaceomorphs by the following combination of features: molars bunodont (in particular, the postmetacrista is nonsalient or only weakly salient); m2 larger than m1; lower molar trigonids somewhat taller than talonids or subequal in height; lower molar paraconids low, well separated from metaconids; lower molar hypoconulid not basally fused to entoconid, not connected to entoconid by a crest, and median in position; and M1–2 hypocone well developed and arising from same level on protocone as anterior cingulum.

Apheliscids for which the tarsus is known can be further distinguished from hyopsodontids by the following features: trochlear groove on astragalus well developed; astragalar foramen absent; trochlear articular surface extends onto posterior surface of astragalus; prominent cotylar fossa present; posteromedial projection of astragalar body absent.

Discussion.—Because the phylogenetic analysis presented below agrees with other cladistically based studies in disassociating Hyopsodus from Hyopsodontidae sensu stricto ( Rigby 1980; Tabuce et al. 2001; Hooker and Dashzeveg 2003), we feel it is appropriate to separate Hyopsodus from other “hyopsodontids” at the familial level. Additional justification for this action is presented with the results of the phylogenetic analysis. Apheliscidae Matthew, 1918 has priority over Louisininae Sudre and Russell, 1982 as the name for “hyopsodontids” other than Hyopsodus .