A cohort proposed by G. G. Simpson in 1945 on palaeontological grounds but regarded by some authorities as artificial, that includes the Carnivora (all of the modern mammalian carnivores), the primitive ungulates (including the elephants and sea cows), the Perissodactyla (tapirs, rhinoceroses, horses, etc.), the Artiodactyla (pigs, camels, cattle, etc.), and the Tubulidentata (aardvarks, etc.), which are believed to have arisen from a common population in the Palaeocene.