PALEOBIOGEOGRAPHY OF LATE TRIASSIC AND EARLY JURASSIC TETRAPODS FROM THE NEWARK SUPERGROUP OF EASTERN NORTH AMERICA

In recent decades, several new assemblages of Late Triassic and Early Jurassic continental tetrapods have been recovered from strata of the Newark Supergroup in Atlantic Canada and the eastern United States. Most of the tetrapod taxa can be assigned to clades known from other regions of Pangea, underscoring the global similarities among tetrapod communities during the early Mesozoic. Many of the Late Triassic forms, however, are distinct at lower taxonomic levels. In particular, one group of mammalian relatives, traversodont cynodonts, appears to have been represented by an endemic Laurasian radiation. The Norian-age tetrapods from the Newark Supergroup share a number of genera or proximate sister-taxa with coeval assemblages from the American Southwest and central Europe. The Early Jurassic tetrapods, best documented from the McCoy Brook Formation of the Fundy basin in Nova Scotia (Canada), for the most part represent genera with an apparently worldwide distribution. This faunal homogeneity during the Early Jurassic is puzzling in view of the fact that the disintegration of Pangea was already under way.