Dentition.—
Some teeth have solid crowns (pleodont); some grow from persistent pulps (coelodont); socketed teeth (thecodont) are inserted in alveoli; some are fused with the supporting bone along the outer rim or top (acrodont); whilst others are developed laterally along the flange-like inner rim of the jaw (pleurodont).
Permian and Triassic Reptiles.—
The history of Reptilia commences in Permian and Triassic times, when they were notably represented by the Theromorphs, Pareiasaurus and Tritylodon in South Africa; the Proterosauria of the European and American Permian and Trias, represented by the lizard-like Palaeohatteria and the dorsally frilled Dimetrodon, with its formidable array of neural spines; also the Rhynchosauria, with their beak-like jaws of the same formations. These two groups constitute the order Rhynchocephalia, which is represented at the present day by the Tuatera of New Zealand.
Triassic Reptile, New Zealand.—
The earliest Australian reptilian record is that of a vertebra of Ichthyosaurus from the Kaihiku Series of Mount Potts, New Zealand (Triassic). This specimen was named I. australis by Hector, but since that species name was preoccupied by McCoy in 1867 it is suggested here that the New Zealand species should be distinguished as I. hectori. The New Zealand occurrence of Ichthyosaurus makes the geological history of the genus very ancient in this part of the world.
Jurassic Reptiles.—
At Cape Paterson, Victoria, in the Jurassic coal-bearing sandstone an extremely interesting discovery was made a few years ago, of the ungual bone (claw) of a carnivorous Deinosaur, probably related to Megalosaurus of the European Jurassic and Cretaceous beds (See Fig. 126, 3, 3 A). The presence of an animal like this in Australia points to the former existence of a concomitant terrestrial animal fauna, upon which the deinosaur must have preyed.
