Tetraclaenodon puercensis (Cope 1881, Scott 1892; Kondroshev and Lucas 2012, Paleocene) was originally considered a member of the Phenacodontidae, close to Phenacodus. Kondroshev and Lucas wrote, "The ungual phalanx is intermediate in morphology between a claw-like and a hoof-like phalanx".

Here in the LRT Tetraclaenodon is transitional between the smaller Monodelphis domestica at the rest of the base of the clade Pantodonta. See below.

Deltatherium fundaminis (Cope 1881, middle Paleocene 60 mya, 14 cm skull length, cat-sized, AMNH 16610) this former creodont and former tillodont nests with other basal pantodonts on thsi page. The large cranial crest anchored large chewing jaw muscles.

Trigonostylops wortmani (Ameghino 1897; Late Paleocene—Early Eocene; est. 1.5m) nests apart from the astrapotheres, close tothe much larger Prodinoceras. derived from the smaller Deltatherium and Tetraclaenodon. The premolars were molarized. The snout remains unknown. The zygomatic arch narrowed posteriorly.

Prodinoceras martyr (Matthew, Granger and Simpson 1929, Late Paleocene, 2.9 m long) is traditionally considered the most basal uintathere. In the LRT it nests between Trigonostylops and the much smaller Apterodon.