THE TUATARA

Evening Post, Volume CVI, Issue 8, 10 July 1923, Page 5

THE TUATARA

REMARKABLE ANCESTRY

STRANGE STRUCTURE AND

RELATIONSHIP

SCION OF A ONCE NOBLE

FAMILY.

Australia does not hold a monopoly in "living fossils." Although she is proud to have the pearly Trigonia shell, a relic of Jurassic times, as well as the little marsupial Anteater (Myrmecobius) reminiscent of the English Purbeck manßupials of an age long past, New Zealand can also boast of a "remarkable reptile, the Tuatara or Sphenodon, declares F. Chapman, A.L.S., palaeontologist to the National Museum, Melbourne, in an article in the "Argus." Two of these interesting creatures have now been added to the Melbourne Zoo. Though called a beaked lizard, a crocodile might lay equal claim to the title of lizard, for it is so peculiar in its structure that it has been placed in a separate order, which includes many fossil representatives. Without desiring to offend this interesting little "beastle," we may truthfully say that it is a lonely scion of a once noble family, whose ancestry runs back 'not merely to a thousand years cr ?o, but on a moderate- estimate to, perhaps 50,000,000. .Although one of the most primitive of reptiles, ifc is generally regarded by naturalists representing the ancestral stock from which tlie higher reptiles, and later, the mammals, were derived. So that its blood is very blue, indeed. *

The Tuatara, to give it the, Maori n.iinc, is now found only on some small islands off the north-east coast of New Zealand. It is certain, however, that at one time it inhabited the mainland, for its bones have been found in the middens along' with those -of trie Moa birds, Dinornis;' and Nbtornis. Since it is one of the most interesting of living animals on the face of the globe, it is satisfactory to learn that tie New Zealand Government has placed it under special protection. In fact, had it not .been immediately protected, the inroads of civilisation in the form of bush fires, clogs, and cats, and even trie Maoris, who are •fond of it for food, the tuatara would have speedily gone the way of the Dodo and Leadbeater's parrot. Living as it does in ,a burrow, this would tend toproteet it to some extent, but even, that does not ensure immunity. It shares its burrow with various kinds of peterels, though, other tuataras are not allowed entry. It is said that, the tuatara lives on the right side of the burrow, and the petrel on the left. When'this, agreement was drawn up no one can say. The eggs which are laid by the tuatara are hatched in the sun. The. incubation occupies a period of 13 months, so that during a part of the time this process must bo arrested by cold. Tuataras are rather lazy in their movements, and slowly drag themselves along the ground unless excited about their food, which they will only take alive, in the _shape_ of small animals. The tuatara., or, scientifically, the sphenodon punctatus (lit. spotted wedgetooth), belongs to the order rhynchocephalia, a dominant group of reptiles in Permian, Triassic, and Jurassic times; but alas, is now. the solitary remaining species. They are lizr.rd-like in shape, and in some points have similar structures, as in the hooklike process on the ribs, seen both in lizards and birds; these uncinate appendages are not, rwyever, found ,in the fossil examples of the order! The nostrils are double, the lower jau-s. connected by cartilage, and the vetebral bones deeply concave both back and front. The palate has a single- row of teeth, separated by a fissure from the row on the edge of the upper jaw. lne teeth -of the lower jaw fit in this groove.. They are not, as is usual with teeth, implanted in sockets, but 'firmly welded to the edge of the jaw Tho front of the jaw is beak-like, hence the' name, and the premaxilla carries a pair of chisel-shaped teeth. On the top of the skull is a vacuity, the parietal foramen, and beneath is a functionless ere or parietal gland. This rudimentary eye is seen through the skin in the younf tuatara, but the skin thickens over as it grows older. .

What is known as the pineal body is a structure seen in fishes and reptiles, as a process of the brain that perforates the roof of the skull. In sharks it ends belo>- the skin in a closed vesicle. Young frogs show it above the surface of "the sxull, but it : undergoes degeneration later in life. De Graf first discovered tms body as an eye-like organ in the British slow-worm (Anguis), and Sir Baldwin fcpencer confirmed it in the present genus Sphendon, as having distinct traces of a retina. Some authorities regard the pineal body as a primitive structure representing an upturned median eye, like the conning tower of a submarine. Others, however, look upon the eye-like structure as a secondary modification. Professor Howes and Dr H Swinnerton, who also worked upon the Sphenodon m regard to the skeleton, found that the vertebrae passed through f t Palr, e(J cartilaginous stage, and in its later details most resembled those of the lower batrachians (group of the frogs and tGUCIS).

_ It is clear that the "beaked-lizards" descended from a stock which also gave use to the frogs and toads of the earlier ages. This is seen by the embyrological and other researches made on both the latter and Sphenodbn. On looking over' the relics of the past, away back for at least 50 milhon years, in the Carboniferous period, we find the earliest backboned animals which exhibit fingered lunhs. Ihese are great amphibians known to palaeontologists as Stegocepualians, whose flattened craniums were formed of a roof of strong bone, apparently made to resist hard knocks Very soon afterwards,; probably within the next nalf-milhon years, in the Permian arose another group of digitated, backboned animals, which, being more or less reiated, are placed with the reptiles. This is the group to which our living Sphenodon belongs, comprised in the order Knynchocephaha, or "beak-heads." _ In the copper slates of Germany and m tne. Permam magnesian limestone of Durham, in Englcrnd, are found some of these earliest "beak-heads." T!ius,- Proterosaurus had a body abot 4Aft'long Another curious animal belonging to this group is the Hyperodapedon, described from some slightly younger beds at Elgin; in Scotland, by. Professor Huxley It had a short, flattened, triangular head and tne upper jaws and palatines were furnished with several rows of flattened conical crushing teeth like enamelled buttons, with a single row on the lower jaws. This probably indicates that it was fond 01 dining upon shellfish. The family to which the living Sphenodon belongs includes several interesting rjncestral forms, some large and others small. The gem of the beaked-lizard family was undoubtedly Homoeosaurus which was very like Sphenodon, but generally smaller, and in some species measuring only about Sin in length. It differed; however; from the living form in not having the hook-like or uncinate processes on the ribs. This little creature must _hav.e been very common near the coast in Upjper Jurassic times, when that peculiar mud deposit was forming in the

Oolitics seas of Europe", and which now is the remarkable lithographic stone. Into the mudbank of this Jurassic shoreline were washed all kinds of flotsam, such as dragon-flies and small animals from the-land as well as -cuttle-fishes and other marine objects from the sea. Excellent casts of fossil beaked lizards from the South African Karoo and the Oolite of France and Bavaria are to be seen in the wall-cases of the gallery of fossils in the National Museum. The most remarkable thing about this group of the Rhynchocephallans is that no remains have been found in any formation between the Jurassic and the sub-recent, so that we can almost say that we possess a living "beaked lizard"—"through the intervention of Providence."