NEW VERTEBRATE LOCALITIES IN THE EARLY PERMIAN OF TEXAS REVEAL COMMUNITIES DOMINATED BY OFFSHORE CHONDRICHTHYANS

The Lueders Formation (Permian, Cisuralian, Artinskian) is a sequence of terrestrial sediments and marine carbonates in north central Texas. In the last century or so of study, vertebrates from the Lake Kemp region of this formation illustrate a terrestrial, riverine, and estuarine community of synapsids, temnopsondyls, xenacanthiform sharks, paleonisciform fishes, and acanthodians. The exposure of the Lueders Formation, however, extends much farther into the Permian Basin than the Lake Kemp region, and we report two localities (in Shackleford and Runnels Counties) with off-shore marine vertebrate communities. The Runnels County site is of particular interest in that vertebrates have never been reported this far into the Permian Basin from this time. The osteichthyan material we recovered from the Runnels County site consists of piscivorous paleoniscoid fishes and platysomid fishes, extending their ranges closer to the mouth of the Permian embayment than previously thought. Among the chondrichthyans we report a hybodontiform shark which may represent a new species, as well as denticles associated with an unknown euselachian. We also recovered the only conodont ever found in the Lueders Formation, cf. Streptognathodus. Analysis of the aquatic vertebrate assemblage across the full spectrum of Lueders depositional environments, suggests that bony fishes ranged across a wider variety of ecosystems than the chondrichthyans, which were somewhat more localized in their occurrences.