New Vertebrates from the Paleogene of Eastern Texas

Although early Paleogene vertebrates have been known since the 19th century in eastern Texas, major questions about the biota, biotic change, and the age of the exposed formations have yet to be addressed. A combination of published data with new field and lab work has expanded the known fossil record of the Paleogene of eastern Texas and has begun to place the Texas stratigraphic column into a regional and global context. Recent work has uncovered the first fossil vertebrates from several Paleocene and Eocene formations including the Calvert Bluff Formation, Reklaw Formation, and Queen City Sand. Additional new vertebrate taxa have been located in the Weches and Cook Mountain Formations.

A recently discovered vertebrate fauna from a storm bed in the Calvert Bluff Formation contains a diversity of sharks, rays, fish, turtles, and crocodilians. The faunal assemblage is most similar to those found near the P-E Boundary in the Tuscahoma and Bashi Formations in Mississippi. This marine Calvert Bluff outcrop (likely equivalent to the term Sabinetown, though lacking glauconite) may be latest Paleocene and would then contain the oldest record of thresher shark (Alopias) and sharpnose shark (Rhizoprionodon). Those taxa are absent in the much larger sample from Mississippi. The Reklaw fauna is diverse with the presence of batoids (Myliobatis and Rhinoptera), sharks (Striatolamia and Serratolamna), and a large lizard. The Weches Formation shark fauna is composed of Synodontaspis, Cretolamna, and Galeocerdo. The Cook Mountain Formation may be the most diverse assemblage with a large number of marine and terrestrial vertebrates including sharks, rays, fish, turtles, lizards, snakes, crocodilians, mammals, and birds. This diverse eastern Texas fossil assemblage will allow for the examination of the biotic response to climate change along the Gulf Coast in the Paleogene and should aid in the further correlation of exposed rock units.