Early Cretaceous (Comanchean) vertebrates of central Texas

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Abstract
Vertebrates from the Comanche Series (Lower Cretaceous) in central Texas occur in the superposed Twin Mountains, Glen Rose, and Paluxy formations. Stratigraphie position and relationship to marine units are more clearly defined for the central Texas localities than for the classic mammal-producing sites in the Antlers Formation of north-central Texas. The diverse terrestrial to marine faunas include new records for the ray Rhinobatos, a ptychodont (cf. Hylaeobatis ornata), and the salmoniform Enchodus. Anurans, salamanders, lacertilians, and mammals representing early forms relevant to the emergence of extant higher taxa are present but fragmentary. Crocodilians are represented by at least three taxa and theropods by more than three. Eight species of mammals have been named from the Comanche Series, with perhaps as many as four other unnamed species represented. Paleoenvironments appear to control the distribution of taxa: dinosaurs are found in coastal settings and are abundant in some terrestrial sites with little aquatic component, while mammals occur in mixed sites with abundant fish faunas. During the Early Cretaceous, the Texas coast was flanked by a broad, flat, carbonate-dominated shelf, and fed by southeast flowing streams in low-relief paleovalleys under a semiarid climate.