Pick up virtually any textbook on vertebrate evolution and you will find mention of the curious reptile known as tuatara (Sphenodon). The special evolutionary status of tuatara as the last of the rhynchocephalians - one of the four orders of living reptiles - is unquestioned. Wild members of the sole living species are now restricted to a few dozen remote islands around the New Zealand coast, where for several centuries they have been observed and studied by humans. But are tuatara really unchanged 'living fossils', or close relatives of dinosaurs, as sometimes portrayed? This is the first detailed monograph for decades about this enigmatic reptile, and the first to be illustrated in colour throughout. The evolution, natural history and conservation of tuatara are covered in comprehensive detail, providing a valuable resource for the specialist yet in a style accessible to a wide readership. The special place of tuatara in Maori and popular culture is also considered. Tuatara have survived alongside humans for more than 700 years, though with their numbers much reduced; what are their future prospects in a globally changing world?