It is in this class that we find the most remarkable changes; and although reptiles are common in the Permian, the abundance and diversity of the Triassic reptiles are incomparably greater. Almost all the orders of Mesozoic reptiles are already represented in the Trias, though often by comparatively small and rare forms. The Triassic reptiles are much more common and better preserved in Europe than in America; but such American genera as do occur show that there was no essential difference between the reptilian faunas of the two continents.

Fig. 286. - Diplurus longicaudatus Newberry. Newark shales. (Dean).