Like the lizards that they resemble, tuatara (Sphenodon punctatus) are members of Lepidosauria, a major group of reptiles accounting for over 9000 species (https://www.reptile-database.org, accessed 1 January 2014). Unlike lizards and their sub-clade the snakes, tuatara are not squamates. Instead, tuatara are the only living representatives of Rhynchocephalia, the sister group of Squamata (Gauthier et al. 1988; Jones et al. 2009; Evans and Jones 2010). As such, they hold considerable evolutionary importance.