PALEOBIOGEOGRAPHY OF THE WESTERN INTERIOR SEAWAY AND THE RELEVANCE OF THE AUSTIN AND TAYLOR GROUPS (UPPER CRETACEOUS) OF NE TEXAS TO THE SOUTHERN PROVINCE

The Upper Cretaceous (Campanian) deposits of NE Texas have long been known to produce large volumes of marine vertebrate fossil material. This study is a new analysis of these vertebrates in relation to biostratigraphically equivalent units in North America and their relevance to the paleobiogeography of the Western Interior Seaway. Previous researchers have suggested dividing the Western Interior Seaway into Northern and Southern Provinces based on the vertebrate faunas. However, the vertebrate fauna of the Upper Cretaceous (Campanian) of Texas has yet to be placed within a biogeographic context of the seaway. Thus making an accurate zonation for the seaway difficult.

The Upper Cretaceous (Campanian) Austin and Taylor Groups of NE Texas are stratigraphically equivalent to the Mooreville Chalk from the Selma Group of Alabama; the Niobrara Chalk of Kansas; the Sharon Springs Member of the Pierre Shale of Wyoming and South Dakota; the Pembina Member of the Pierre Shale of Manitoba and the Smoking Hills Formation of the Anderson River in the Northwest Territories. The vertebrate faunas of the Austin and Taylor Groups are most similar to those of the Selma Group of Alabama, although bearing much similarity to those of the Niobrara. This analysis will discuss the faunal similarities of these units and will place the Austin and Taylor Groups into the paleobiogeographic framework of the Western Interior Seaway.