Both the start and end of the Triassic are marked by major extinction events. The extinction event that closed the Triassic period has recently been more accurately dated, but as with most older geologic periods, the rock beds that define the start and end are well identified, but the exact dates of the start and end of the period are uncertain by a few million years. During the Triassic, both marine and continental life show an adaptive radiation beginning from the starkly impoverished biosphere that followied the Permian-Triassic extinction. Corals of the hexacorallia group make their first appearance. The first flowering plants (Angiosperms) may have evolved during the Triassic, as did the first flying vertebrates, the pterosaurs. During the Triassic, almost all the Earth's land mass was concentrated into a single supercontinent centered more or less on the equator, called Pangea ("all the land").The remainder was the world-ocean known as Panthalassa ("all the sea"). The supercontinent Pangaea was rifting during the Triassic, especially late in the period, but had not yet separated; the first marine sediments in the earliest rift, which separated New Jersey from Morocco, are Late Triassic in origin. The Early Triassic climate was generally hot and dry, forming typical red bed sandstones and evaporites. There is no evidence of glaciation at or near either pole; in fact, the polar regions were apparently moist and temperate, a climate suitable for reptile-like creatures. The shelled cephalopods called Ammonites recovered, diversifying from a single line that survived the Permian extinction. The fish fauna was remarkably uniform, reflecting the fact that very few families survived the Permian extinction. There were also many types of marine reptiles. Source