(1) Similar features have been seen in Permian and Triassic conifer trunks from Antarctica and North America.(2) Uppermost Permian and Triassic terrestrial sediments conformably overlie the terminal volcanic rocks.(3) It happened 252 million years ago, at the boundary of the Permian and Triassic geological ages.(4) The ancestral archosaurs probably originated some 250 million years or so ago, in the late Permian period.(5) Throughout the Permian period the numbers of invertebrate species tends to decrease.
