NATURE NOTES

New Zealand Herald, Volume LXVI, Issue 20426, 30 November 1929, Page 1 (Supplement)

NATURE NOTES

WHEN THE MOAS CAME.

BY J. DRUJIMOND, F.L.S., F.Z.S.

If Dr. J. Warwick, of the New Zealand Geological Survey, is correct in his opinion that the ancestors of the moas walked into New Zealand during the Lower Cretaceous Period, those old birds came so long ago that it is difficult for people who are not geologists to think clearly back to that event through the mists of

time. The Lower Cretaceous was not very remote geologically. It was about the middle of the era of Middle Life, the Mesozoic, in geological terms. It is wedged in between the era of Ancient Life, the Palaeozoic, and the era of Recent Life, tho Cainozoic. Yet computators, using the latest means of computation, provided by radio-activity in rocks, place the Lower Cretaceous Period at a . time perhaps 100,000,000 years ago.

In the New Zealand area, which then, apparently, was much larger than it is now, it was a time of intense wrinkling, puckering, shrinking, tilting and fracturing of the surface of the land. These movements were upward, downward, or horizontal. Some were rapid and tiny, others slow and gigantic. There was ample allowance for the most deliberate movements. The Lower Cretaceous Period may have continued for many thousands of millenniums, to be succeeded by the Upper Cretaceous, 50 per cent, longer in duration, before New Zealand and the rest of tho world entered upon the Recent Era. New Zealand, several times, was much larger than at presenj. Dr. Marwick finds that in the Lcwer Cretaceous

it saw its greatest extension, with, possibly, continental connections north lo Malaya and south to Antarctica, Not long previously, counting time by the vast geological clocks, New Zealand had less important land connections in the_ Triassic Period and in the Jurassic Period, and later, after the Cretaceous Period came to an end.

The Cretaceous Period's mere title, like many other titles, is empty and meaningless. It is borrowed from creta, the Latin name for chalk. Its reference is to the fact that rocks of that period in Western Europe contained much chalk. Cretaceous rocks are world-wide. They are among the rock systems most extensively developed. In some regions they coyer hundreds of thousands of square miles in a continuous sheet.. Almost continuous is a Cretaceous belt running from Cape Campbell, Marlborough, to close to Waipara, North Canterbury. Not all Cretaceous rocks are chalky. Chalk is borne in rocks that do not belong to the Cretaceous. Sands, clays and shales, as well as limestones, are the prevailing rocks of the Cretaceous Period.

One deep calling to another, Cretaceous waters raged and swelled and advanced over the low-lying maritime lands of every continent of the world. It is the greatest transgression of the sea ever known. One theory to account for this unprecedented advance is the collapse of a great continent called Gondwana. It seems to have occupied the site now filled in by the ludian Ocean and the South Pacific Ocean. There is no geological evidence connect New Zealand with the lost continent, although some students believe that New I Zealand may have been one of its foreshores.

The continent's collapse would cause profound disturbances on the earth's surface, raise the level of the ocean, and give the sea its opportunity to advance on the land. Cretaceous seas extended from the Atlantic east through terranean area to Asia Minor, Persia and India. They swept over most of North Africa's deserts. They spread over the Great Plains of North America to the Arctic Ocean. The Cretaceous Period in India, saw volcanic outbursts Unparalleled in the earth's history. Floods of lava overwhelmed most of the Indian Peninsula, in places 10,000 ft. deep. The lavas are called the Deccan Trap.

In many respects the Cretaceous was the most momentous period in the world's history. It was rich in giants. .Huge dinosaurs, notably Iguanodon and Megalosaurus, reached their, greatest development, declined, and disappeared. A monster of the seas, Mosasaurus, 75ft. long, lived in those days. The Cretaceous Amuri Bluff, on the coast north of Waipara, North Canterbury, entombed many reptiles belonging to races which, in the Cretaceous Period, received their dismissal. In other lands —there is nothing to show that they lived in New Zealand—Pterodactyls, with their leathery wings spreading perhaps 20ft., had dominion in the air. Plesiosaurs, seal-like, stupid and slow, swam in all Cretaceous seas, including New Zealand's.

Out in the oceans the rulers were the formidablo Mosasaurs, great sea serpents, their power and voracity evidenced by their jaws and teeth. All those giants had a low type of brain. Their organs were 'not highly specialised. Their energies were exhausted. They relied on their strength. Their vitality decreased; they did not feel it requisite to meet changing conditions, and every dynasty perished. The moas were greatest among birds, if size alono counts for greatness. Their ancestors continued in lordly stato long after the Cretaceous Period had passed; but in recent times the moas, like all the Cretaceous giants, were extirpated.

Sediment deposited by Cretaceous seas has given the first records of the appearance of 1 lie aristocrats', intellectuals, Apollos and Vcnuses, of the vegetable kingdom, the flowering plants. In lower Cretaceous times the plants took the most important step in their earthly pilgrimage. Their previous history is concerned mainly with ferns, horsetails, lycopod;;, cycads and conifers. Whole groups of these, like the gigantic animals, reached a standard, throve too well, and disappeared. Other groups dwindled in size, number and importance, but still survive, to occupy a place minor to plants that have gone ever onward.

No very clear explanation has been made of tho correlation between monstrous size and extinction. Races of mammals, reptiles, amphibians and lower creatures, in the Cretaceous Period, or in later periods, developed exuberantly, acquiring a momentum in growth that ended in death. All tho gigantic amphibians, all the gigantic fishes, all the vei'y gigantic reptiles, have been blotted out. The gigantic mammals, which developed later than Cretaceous days, are represented in our times by a few species of whales and by two species of elephants. These man seems destined to destroy. The gigantic moas received sentence "under tho same natural law. A voracious and plentiful race of molluscs, the Ammonites, well represented in New Zealand's rocks, attained amazing size in some species, and departed betore the Cretaceous Period closed. Another mollusc the Nautilus, survived the Cretaceous Period, and lives still ln wa ""> temperate and tropical seas Its persistence is explained by its habitat being in open, deep seas, where it might not be affected by the changes of the .continents. It s?ems never to hare aimed , at bigness.