The tuatara of New Zealand (Sphenodon punctatus; pictured), formerly thought to be a lizard, was recognized 150 years ago this month as the only living member of its own reptile group — Rhynchocephalia (A. Günther Phil. Trans. R. Soc. 157, 595–629; 1867).
The tuatara's ancestors separated from those of lizards and snakes (Squamata) around 240 million years ago. The frame-like skull of S. punctatus, long believed to be an archaic feature, is in fact a specialization for supporting its powerful jaws (D. I. Whiteside Phil. Trans. R. Soc. Lond. B 312, 379–430; 1986).
The animal's taxonomic isolation has turned it into a flagship species for studies of evolution, biodiversity and conservation (see, for example, A. Cree Tuatara Canterbury Univ. Press; 2014).
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