Pantotheria (class Mammalia, subclass Theria) An extinct infraclass of primitive Middle and Upper Jurassic mammals, known from N. America, Europe, and E. Africa. They were egg-laying insectivores of shrew-like appearance, and are believed, on the basis of the structure of the jaw and teeth, to include the ancestors of all later placental and marsupial mammalian groups. They were distributed widely by the later Jurassic, were numerous, and were varied in form.

Pantotheria (class Mammalia, subclass Theria) Extinct infraclass of primitive Middle and Upper Jurassic mammals, known from N. America, Europe, and E. Africa. They were egg-laying insectivores of shrew-like appearance, and are believed, on the basis of the structure of the jaw and teeth, to include the ancestors of all later placental and marsupial mammalian groups. By the later Jurassic, they were widely distributed, numerous, and varied in form.