amniotes (reptiles, birds, and mammals). Reptiliomorphs are all animals sharing a more recent common ancestry with living amniotes than with living amphibians. Gaffney (1979) provided the name Neotetrapoda to the crown group of tetrapods, though few subsequent authors followed this proposal.

The earliest fossils attributed to crown-group tetrapods are footprints from the earliest Carboniferous (Tournaisian) of Australia, which appear to belong to early amniotes