Lepidosauria

The Lepidosauria (from Greek meaning scaled lizards) are reptiles with overlapping scales. This subclass includes Squamata and Rhynchocephalia. It is a monophyletic group and therefore contains all descendents of a common ancestor. The squamata includes snakes, lizards, and amphisbaenia. The Sphenodontidae are now only represented by two species of tuatara native to New Zealand although they were much more widespread and varied 200 million years ago. Lepidosauria is the sister taxon to Archosauria, which includes Aves and Crocodilia. The only surviving tuataras are the family Sphenodontidae, genus Sphenodon. Lizards and snakes are the most speciose group of Lepidosaurs and combined contain about 7,970 species. However, the tuatara, which is found in New Zealand, has only two remaining species. There are noticeable distinguishing morphological differences between lizards, tuataras, and snakes.