Category
page 1Tetrapods
Tetrapoda
A tetrapod (; ) is any vertebrate animal of the clade Tetrapoda (). Tetrapods include all extant and extinct amphibians and amniotes, with the latter in turn evolving into two major clades, the sauropsids (reptiles, including dinosaurs and therefore birds) and synapsids (extinct "pelycosaurs", therapsids and all extant mammals, including humans).

quadrupedalism
thumb|The zebra is a quadruped.