a zoological name applied to a group of primitive carnivorous mammals from the Santa Cruz beds of Patagonia, represented by the genera Borhyaena, Prothylacinus, Amphiproviverra, &c. By their first describer, Dr F. Ameghino, they were regarded as nearly related to the marsupials. They are, however, more probably members of the creodont Carnivora (see Creodonta).