Enigmatic Oligocene Carnivores Re-examined

Ever since its original discovery in the 1920s, Amphicticeps has remained something of an enigma in regard to its phylogenetic relationships to other carnivoran mammals. A reexamination of specimens of Amphicticeps and the closely related genus Amphicynodon from the Hsanda Gol Formation of Mongolia has reveal new incite into the phylogenic relationships of basal carnivores. Carnivores are loosely divided into two major groups one containing dogs, bears, weasels, seals and raccoons, the other containing cat-like carnivores. The first group arose from the archaic fossil family Miacidae and diversified into two infraorders (Cynoidea and Arctoidea) during the early Cenozoic. Cynoidea contains the dog-family, while Arctoidea contains the larger group of predators, including the living families of bears (Ursidae), seals, sea lions, and walrus (Phocoidea /Pinnipedia), red pandas (Ailuridae), raccoons (Procyonidae), weasels, badgers, and otters (Mustelidae), as well as the extinct bear dogs (Amphicyonidae). A separation of Arctoidea into Musetelida (weasel-like mammals) and Ursida (bear-like/seal-like mammals) is supported by a number of studies. The phylogenic study of Xiaoming Wang, Malcolm McKenna and Demberelyin Dashzeveg (2005), support a basal Ursida position for both Amphicticeps and Amphicynodon. The continent in which bears arose is still a matter of contention, but by the early Oligocene Asia contained a handful of bear ancestors.

WANG, XIAOMING, McKENNA, MALCOLM C., DASHZEVEG, DEMBERELYIN 2005 Amphicticeps and Amphicynodon (Arctoidea, Carnivora) from Hsanda Gol Formation, Central Mongolia and Phylogeny of Basal Arctoids with Comments on Zoogeography American Museum Novitates 2005 3483: 1-57