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Tuatara

Tuatara

Tuataras (class Rhynchocephalia) superficially resemble lizards (class Reptilia), but the two known species are actually members of the smallest terrestrial vertebrate class on Earth, the Rhynchocephalia, a unique and ancient evolutionary lineage whose fossils (from Asia, Europe, North and South America, and Africa) first appeared in the early Triassic more than 220 million years ago. Today, Tuataras are found only on about thirty islands off the coast of New Zealand; their ancestors on other continents became extinct around 65 million years ago.

Male Tuataras lack a penis or other copulatory organ (unlike mammals, turtles, reptiles, crocodilians, and birds), possess a skull with two pairs of arches (like crocodilians), exhibit teeth on the palatine bones of the jaw (unlike lizards), and have teeth that are set squarely on the jawbone (with limited ability for replacement when lost, unlike the class Reptilia); old individuals may have teeth worn entirely away. Tuataras lay shelled eggs on land (unlike the class Amphibia), and the eggs may take as long as fifteen months to hatch. Tuataras live in burrows, emerging mostly at night but sometimes during the day to bask in the sun.

Tuataras are long-lived, apparently reaching over one hundred years of age. Males are larger (up to 61 centimeters [2 feet] in length and 1 kilogram [2.2 pounds] in weight) than females (45 centimeters [1.4 feet], .15 kilograms [.33 pounds]). They are insectivorous (depending on insects for food), but will opportunistically prey on small vertebrates. Tuatara is a Maori word meaning "peaks or spines on the back," in reference to the conspicuous middorsal crest on the back and tail of males and, to a lesser extent, females. Access to much of the remote island habitat of this animal is difficult, providing it with protection from human disturbance; historically, on those islands where access was less daunting, humans arrived, and the tuataras became extinct.

see also Amphibian; Crocodilians; Extinction; Reptile

Joseph T. Collins

Bibliography

Pough, F. Harvey, et al. Herpetology. Upper Saddle River, NJ: Prentice Hall, 1998.

Robb, Joan. New Zealand Amphibians and Reptiles. Auckland, Australia: Collins, 1986.

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tuatara

tuatara (tōō´ətär´ə) or tuatera (–tā´rə), 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.

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tuatara

tuatara Nocturnal, lizard-like reptile of New Zealand; remarkable for being active at quite low temperatures for a reptile (7°C/45°F) and for being the sole surviving member of the primitive order Rhynchocephalia. It is brownish in colour and has an exceptionally well-developed pineal body on its head, thought to be a vestigial third eye. Length: to 70cm (2.3ft). Species Sphenodon punctatus.

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tuatara

tuatara large lizard having a dorsal row of spines. XIX. — Maori, f. tua on the back + tara spine.

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tuatara

tuatara (Sphenodon punctatus) See SPHENODONTIDAE.

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