Making New Zealand vol 01 no 01: The Beginning
Giant Reptiles of the Sea
Giant Reptiles of the Sea
A Mosasaurus, an elongated reptile of the Mesozoic Era, the appearance of which is as fearsome as its name. This scraper-board drawing was based on data in S. W. Williston's 'Water Reptiles of the Past.'
IN Upper Cretaceous times the New Zealand seas were peopled by great marine reptiles, or saurians. The fantastic land reptiles of this period in the Northern Hemisphere did not exist here. But the long-necked sea lizards, or Plesiosaurs, which took the place of the whales and other sea mammals of modern times, lived in our seas in great numbers. Their fossil remains have been discovered in the Weka Pass—Waipara district of Canterbury and at Amuri Bluff, south of Kaikoura.
An aerial view of the Canterbury Plains and Pegasus Bay. This infrared photograph has eliminated all haze, but has turned the sea to an unnaturally dark colour. The Kaikouras can be clearly seen in the distance. V. C. Browne
These ancient reptiles were most fearsome in appearance. The head of the Plesiosaur was snakelike in shape, while its neck was longer in proportion than that of any other animal. The body was thick-set, and the tail short and stout. Two pairs of large paddles provided adequate locomotion. The teeth were long, slender, pointed, and back-wardly curved—efficient weapons for a flesh-eating monster which sometimes reached a length of fifty feet, though the New Zealand species were only ten feet long.
The Mosasaurs were equally remarkable flesh-eating sea-reptiles which attained a length of thirty feet. The body was greatly elongated and the limbs converted into swimming paddles. The skull, up to five feet in length, was large in proportion to the rest of the animal, and the jaws were armed with numerous sharp, strong, conical teeth, showing the fiercely carnivorous habits of these fish-eaters.
Neither of these ferocious monsters survived the Cretaceous Period.
Less spectacular, but highly important products of the Cretaceous Period are New Zealand's oldest coal-fields at Greymouth and at Kaitangata in Otago. After the retreat of the Mesozoic seas the land surface was low and forests flourished. Great quantities of peat and of the remains of plants— stems, trunks, pollen-grains, and so on—accumulated in depressions of the land, or drifted into lagoons or wide tidal estuaries. As the seas advanced once more, these piles of vegetable material were covered by sands and clays, and the pressure of this load of sediment changed the partly decomposed plants into the valuable rock known as coal.