Trogosus castoridens (Leidy 1871, Eocene 54-33 mya; 35 cm skull length) is known from a large skull (up to 35 cm long). Formerly considered the largest tillodont, Trogosus nests here with Microsyops, close to the origin of Placental3 taxa. This bear-like herbivore left no descendants.

OC Marsh (1875) wrote, "These animals are the among the most remarkable yet discovered in American strata, and seem to combine characters of several distinct groups, viz: Carnivores, Ungulates, and Rodents. In Tillotherium (=Trogosus), the type [specimen] of the order, the skull has the same general form as in the Bears, but its structure resembles that of Ungulates. The molar teeth are of the ungulate type, the canines are small, and in each jaw there is a pair of large scalpiform incisors faced with enamel, and growing from persistent pulps, as in Rodents."

Tillodon fodiens (Gazin 1953) is known from a complete skull about 42cm long. It had a large overbiate and no sliding jaw joint. Note the tiny eyes.

Radinskya yupingae (McKenna et al. 1989, Holbrook 2014; IVPP V-5255; Middle Paleocene; China) was originally considered a perissodactyl-like herbivore, but never with confidence. Here Radinskya nests with the much larger Tillodon. Note the tiny orbit in both.

Pleuraspidotherium aumonieri (Lemoine 1885; Paleocene) was originally considered an unugulate close to Anthracotherium, then an insectivore. Here it nests with Siamotherium as a tillodont = plesiadapiform in the LRT. Note the long premaxillary teeth and maxillary notch with diastema. The dentary has procumbent incisors. The premolars are molarized.