Giant Reptiles of the Sea

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.

As long ago as 1874 the geologist, Sir James Hector, had assembled portions of forty-three reptiles, mostly of gigantic size and belonging to at least twelve distinct species. Besides six different Plesiosaurus, Hector recognised an extremely elongated reptile, a Mosasaur, and some one of which he named Taniwhasaurus after the fabled monster of the Maoris.

These ancient reptiles were most fearsome in appearance. The head of the Plesiosaur was snake-while its neck was longer in proportion of any other animal. The body was thick-set the tail short and stout. Two pairs of large paddles provided adequate locomotion. The teeth were long, slender, pointed, and backwardly curved— efficient weapons for a flesh-eating monster which sometimes reached a length of fifty feet, though the New Zealand species were 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.