A tetrapod (; from Ancient Greek τετρα- (tetra-) 'four', and πούς (poús) 'foot') is any four-limbed vertebrate animal of the superclass 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...