RISKED LIFE – For a Living Fossil

Auckland Star, Volume LXX, Issue 177, 29 July 1939, Page 2 (Supplement)

RISKED LIFE - For a Living Fossil

THE geological past is divided into three great eras, each one characterised by an assemblage of fossil remains that were very-dis-tinctive. This the Paleozoic or first of these great divisions saw the first fishes and many primitive organisms quite unlike those of to-day. The most remarkable were the trilobites, crab-like creatures, which resembled the common wood louse, but on a larger scale. Trilobites came into being in the early Paleozoic, had their heyday and finally dwindled and became extinct before the close of the period. Just as an Individual has his birth, prime and senility, so do types of organisms over a pejiod of time. One would hardly expect to find living to-day any creatures closely allied to those of the distant Paleozoic, yet there arc a few exceptions —notably Liiigula, one of the so-called "lampshells," the recent representatives of which are scarcely different from their ancestors of 500.000,000 • years back. Lingula has a care-free life, buried some inches below the surface of soft mud. Apparently from the outset this conservative animal found things to its liking, and either did not hear of or cared little for the concept of evolution. A stick in the mud, perhaps, but it has certainly been rewarded for its patience and its contentment with its lot. The second <rreat era—the Mesozoic, or middle, period—was the great age of giant reptiles; the seas swarmed with coiled shellfish of the nautilus type, which we term ammonites. Neither the giant reptiles nor the ammonites survived to the third period —-the tertiary. Geologists also listed with the extinct types of that Mesozoic a ribbed, pearly cockle-like shell known as Trigonia. Imagine the delight of the French naturalist Perou when in 1802. while on the exploring vessel Geographe, he found on the beach at King Island. Bass Strait, a specimen of a living species of

By---A. W. B. Powell

Trigonia. Later, Quoy and Gaimard. of the French vessel Ufanie, discovered living examples in southern Tasmania. Unfortunately the Uranie was wrecked at the Falkland Islands in 1820, but Quoy risked his life in returning to his cabin to rescue the precious Trigonias. He declared that he would rather die in this attempt than return to France without the proof that in faraway Tasmania the Mesozoic Trigonia still existed as a '"living fossil.'' New Zealand, however, has the most remarkable living fossil in the tuatara, which is a direct descendant of the great reptiles of the distant past. Although resembling a lizard and often termed one, it ranks as a separate group along with the other four main orders of reptiles—namely, the snakes, the tortoises, the crocodiles and the true lizards. The ribs of the tuatara have backward projections that are similar to those found in crocodiles and birds, while the skull is remarkably bird-like in structure. The teeth also are not separate and socketed, but are actual serrations of the jaws. Frequent reference has been made to the so-called third eye of the tuatara. This parietal or pineal eye possesses all the characteristics of a simple eye, but it is completely covered by skin and is invisible from the outside except in very young examples. It is considered to be the remnant of an original pair of eyes—the left one—for there is also a "vestige of a former right eye represented as an elongated body beneath the left. Lack of competition from higher animals and perhaps less rigorous conditions during past ages in the Xew Zealand area as compared with the continents has enabled this remarkable living fossil to survive to the present day. r

The creature's temperament has helped, no doubt, for the tuatara is seldom in a hurry. One was kept in Dunedin for over 50 years, and the Maoris of Motiti Island, in the Bay of Plenty, assert that there has been one in a shell pit on the island that has lived there for 300 years. If this seems incredible, it must be remembered that tortoises kept in captivity in Europe have been known to 1ive.250 years. The fact that the teeth of the tuatara are part of the jaw once occasioned the facetious remark that a tuatara would be unable to distinguish between toothache and headache! Australia also is a land noted for its living fossils. This is to be accounted for by its long isolation from other large land areas, the intervening land keeping out higher animals better equipped for the battle of life and allowing the primitives to go their own way and develop without interference. Thus Australia has the platypus and spiny anteater. the only surviving members of that primitive stage in mammalian evolution when the reptilian habit of laying eggs persisted. Only a stage higher in development are the marsupials, such as the kangaroo, wallaby and opossum, in which, as everyone knows, the young are sheltered in a pouch and forcibly fed. Marsupials were not restricted to Australia, however, for in past ages they lived in Europe. America still has in the true opossum a creature of ancient lineage that is regarded as being near to the prototype from which all existing marsupials have descended. Almost Extinct In fishes there is the Port Jackson shark, a small, harmless species that belongs to a group once strongly represented in many parts of the world, but now practically extinct except in Australian seas. The Queensland lung fish is another archaic creature, whose relatives date back to the far-distant Devonian period. The discovery of the century, however, is the Crossopterygian fish recently trawled from off East London. South Africa. This type of fish was believed to have become extinct in the C'retacious over 50.000.000 years ago. Imagine the thrill of a fish expert. striving to piece together the characters of a type represented only by fossilised, imperfectly preserved frag nients and impressions in the rocks, at last confronted with the real thing in the flesh, complete in every detail, even to colour! Those who laboriously pieced together this information from the fossil remains, now have the satisfaction of knowing that their reconstruction was exact, and this should aNo impiv:— all who are sceptical of these reconstructions from similar fossil material. One of the prized possessions of the -Auckland Museum is three scales from this South African fish donated by Mr. W. A. Sargent, of South Africa. There are scores of other examples of still living fiyssils. large and small, from a tiny blind Crustacean from wells in Canterbury, described by the late Professor Chilton, to that" queer African animal, the Okapi. which is virtually a still living early evolutionary stage in the development of giraffes, but minus the long neck. Nature has indeed been kind in not always eliminating the primitive but allowing to persist certain key types of organisms that serve a=i milestones in the elucidation of the history and development of animals generally.