NEW OCCURRENCE OF EILENODON ROBUSTUS FROM THE AARON SCOTT QUARRY, MORRISON FORMATION (JURASSIC), UTAH

Eilenodon is a rare sphenodontian found in the Morrison Formation. Two new nearly complete dentaries of Eilenodon have been recovered from the Aaron Scott Quarry, Jurassic Morrison Formation of central Utah. The type specimen was described from the Fruita Paleontological area based two lower jaw fragments. The species is different from other sphenodontians of the Morrison Formation in having labiolingually expanded teeth, representing an herbivore (Rasmussen and Callison, 1981). Additional specimens have been collected from Westwater Canyon, Utah, Dry Mesa, Colorado and Garden Park, Colorado (Foster, 2003). A.S.S. 1371 is 5 cm long with 17 teeth preserved. The largest tooth is 3mm wide by 1.5mm deep. The jaw is 1.5 cm deep at the posterior-most tooth and tapers to 0.8cm at its shallowest point at tooth 13. All teeth are worn and the primary wear facet curves anterolingually. Teeth are progressively more worn anteriorly so that the anterior most teeth are nearly at the dentary line. A.S.S. 1402 is 4.1 cm long with 13 teeth preserved. The anterior-most portion of the jaw is broken off. The teeth are nearly horizontal labiolingually with little wear. The jaw is 1.4 cm deep at the posterior-most tooth and tapers to 0.7cm at its shallowest preserved point at tooth 13. These dentaries represent the most complete specimens of Eilenodon described.