THE TUATARA

Bay of Plenty Beacon, Volume 7, Issue 7, 23 September 1942, Page 6

THE TUATARA

OUT OF THE MESOZOIC

Most noteworthy of New Zealand's animals is the Tuatara, commonly thought of as a lizard but actually being just as closely allied to crocodiles, birds and especially turtles and tortoises. A single species, with no living relatives, it forms one of the live great groups into which living reptiles are divided. Its nearest known relative is a fossil found in certain European rocks of Jurassic age (about 150,000,000 years old)! It thus antedates both birds and mammals. It is rightly referred to as a living fossil. In external appearance it resembles a lizard (but differs from the lizards in many ways), and when full grown is about 15 inches in length with a massive head and a spinous crest running along the neck, back and tail. It is greenish yellow to grej'' in colour, and the skin is loose, tough and scaly. In the head, there is a third eye, the medium or "pineal'" eye. This is a perfect little eye, 1-50 inch in diameter, with lens and retina, underlying a transparent scale on the top of the head. Just how it functions is not known.

Still more interesting is the remarkable occurrence of. suspension of development of the embryo within the egg during the winter months. The eggs are laid early in summer, and growth of the embryo proceeds normally until autumn, when an advanced stage of development has been reached. Further growth then

ceases until just before the egg is hatched the following summer. This veiy unusual winter "sleep" within the egg is found also in the European tortoise. There are other features of the Tuatara's development that .show its close relationship with the turtles and tortoises, although the fullgrown animals are so totally different in appearance. The skeleton has the generalised structure of the fossil reptiles of early Mesozoic times, and shows its relationship with birds, crocodiles and. lizards also. The Mesozoic was the great Age of Reptiles. Mammals appeared later in the earth's history. Even the soft parts of the Tuatara exhibit primitive structures. Although the Tuatara was once plentiful on the mainland of New Zealand, it is now found only on outlying islands. It lives in a burrow, which it shares with a nesting petrel. Its food, which is caught alive, consists of spiders, - insects, snails, and. any small animals. Tfiough its movements appear to be sluggish it nevertheless can move in short swift dashes, but is incapable of jumping even a small obstacle. Its habit of lying full length in the water is thought to be a .survival from the remote past for many of its ancestors were amphibious in habit., This most interesting animal linlks the present with the long bygone geologic past. It is protected by. law. Its scientific and educational value is so great that much greater efforts than are evidenced at present should lie made to ensure its preservation.