Vertebrates and the Permo-Triassic extinction

The fossil record of vertebrates in the late Paleozoic and early Mesozoic is investigated in an attemp to evaluate their participation in the Permo-Triassic faunal crisis. On the whole the record of the marine fishes is similar to that of marine invertebrates with a pronounced diversity minimum at the end of the Permian. On the other hand, the fresh-water and euryhaline fishes, together with the amphibians, seem to have experienced minimal diversity somewhat earlier in the Permian and apparently were on the increase at the Permo-Triassic boundary. The major peculiarity in the reptilian record is a great burst of both first appearances and apparent extinctions in the Dzhulfian Stage in Africa; local causes are suspected. Seemingly the Permo-Triassic faunal crisis was mainly a marine event for which a marine cause or causes should be sought.