tuatara(redirected from Beak-head)
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tuatara (to͞oˌətärˈə) or tuatera (–tāˈrə), lizardlike reptile, Sphenodon punctatus, last survivor of the reptilian order Rhynchocephalia, which flourished in the early Mesozoic era before the rise of the dinosaurs. Also called sphenodon, it is found on islands off the New Zealand coast and in Karori Wildlife Sanctuary, Wellington, New Zealand. The olive colored, yellow-speckled tuatara reaches a length of 2 ft (60 cm) or more. It is very lizardlike in external form, with a crest of spines down its neck and back. However, its internal anatomy, its scales, and the attachment of its teeth are quite different from those of lizards, and its body chemistry allows it to function at temperatures close to freezing. Like certain lizards, it possesses a vestigial third eye (pineal eye) on top of its head, but this organ is probably not sensitive to light. Tuataras usually inhabit the breeding burrows of certain small petrels. They feed on small animals, especially insects, and reproduce by laying eggs. Captive tuataras mature in about 20 years, and it appears that their life span may exceed a century by several decades.
Tuataras lived on the mainland of New Zealand before the arrival of the Maoris but either were exterminated by hunting or died out as a result of the altered environment. Their survival on the offshore islands was threatened by the introduction of sheep, which altered the vegetation by grazing; however, they are now under strict government protection, and their numbers are increasing. In 2005 tuataras were reintroduced on the mainland at the Karori Wildlife Sanctuary.
Tuataras are classified in the phylum Chordata, subphylum Vertebrata, class Reptilia, order Rhynchocephalia.
(Sphenodon punctatum), the sole surviving representative of the subclass Rhynchocephalia, known from the Triassic. Tuataras have biconcave vertebrae, two pairs of temporal fossae and two corresponding cranial arches, a quadrate bone immovably attached to the skull, a well-developed pineal body, and, as in fish, a sinus venosus in the heart. Externally, a tuatara resembles a lizard, with its massive body, large head, and penta-dactyl legs. On the back and tail is a low ridge of triangular scales. The body coloring is a dull olive-green.
Tuataras occupied both main islands of New Zealand prior to the arrival of the Europeans, but they were subsequently exterminated. They have survived only on rocky islets in the Bay of Plenty, where a special sanctuary was created for them. Tuataras live in holes approximately 1 m in depth, in which small petrels also frequently nest. They are active at twilight and at night. They feed on insects and other invertebrates and occasionally the eggs and nestlings of petrels. Mating takes place in January. From October to December, females lay eight to 15 hard-shelled eggs in the holes. Embryonic development lasts 12–15 months. Sexual maturity is not reached until age 20. Some tuataras have been known to survive as long as 50 years in captivity.
I. S. DAREVSKII