Djadochtatherium Simpson, 1925 is a junior synonym of Catopsalis Cope, 1882. Known species of Catopsa!ts (Djadochtathertum inclUded) form a morphological sequence, beginning with Asian ?Late Santonian and/or Early Campanian C. matthewi, and ?Middle Campanian C. catopsaloides, through the following North American species: Late Maastrichtian C. joyneri, Paleocene C. foliatus, C. utahensis, C. fissidens and C. cagartensis. Morphological changes involved an increase in size, a reduction of the number of upper premolars, relative reduction of the size of the lower fourth premolars, and an increase of the number of cusps on the molars. It is believed that Catopsalis, and possibly the family Taeniolabididae originated in Asia, developed there during the ?Late Santonian-?Middle Campanian and spread to North America during the Late Campanian or Early Maastrichtian.