Theria

Theria ( or ; ) is a subclass of mammals amongst the Theriiformes. Theria contains the eutherians (which includes placental mammals) and the metatherians (which includes marsupials) but excludes the egg-laying monotremes and various extinct mammals evolving prior to the common ancestor of placentals and marsupials.

Patagomaia is an extinct mammal of uncertain affinities, originally described as a therian mammal, from the Maastrichtian Chorrillo Formation of Argentina. It is the largest Mesozoic mammal yet known, with weight estimates of around . The genus contains a single species, Patagomaia chainko, known from various fragmentary bones.