Theriimorpha

Theriimorpha is a clade of mammals defined as including all mammals more closely related to therians (including placentals and marsupials) than to monotremes. Eutriconodonta is usually considered among the most basal members of this group, with other members more closely related to therians like Allotherians placed in the subclade Theriiformes, though Eutriconodonta has also been recovered as less closely related to therians than monotremes are in some analyses, placing them outside the crown group of Mammalia. The unusual Late Jurassic digging mammal Fruitafossor has also been suggested to be a basal theriimorph. Although a 2018 study recovers Friutafossor as a stem monotreme. A 2024 study recovers the eutriconodonts as therimorphs, as well as the Australosphenids as pan-monotremes, but destroys Theriiformes by expelling Allotheria as a whole out of the crown group of mammals.