New Mexico Geological Society Annual Spring Meeting — Abstracts

The gigantic sauropod dinosaurs are the most commonly recorded vertebrates from the Upper Jurassic Morrison Formation, including famous dinosaur quarries in Colorado, Utah, Wyoming and Oklahoma. However, sauropod skulls remain exceedingly rare. We report an incomplete skull and lower jaws (NMMNH P-26082) from NMMNH locality 3282, the Peterson Quarry, which is the most productive Jurassic dinosaur locality in the state. The specimen was found in a float block but is clearly associated with the numerous other specimens from the Peterson Quarry. The float block was found close to a quarry wall, and was probably derived from the south end of the quarry as it was worked from 1989-1995.

The partially disarticulated and crushed skull consists of an incomplete right premaxilla and maxilla, incomplete left mandible, several palatal(?) skull fragments, and 33 teeth, all preserved in two matrix blocks. Of the teeth, 19 are associated with the larger matrix block and 14 with the smaller one. Diplodocid synapomorphies present in P-26084 include the presence of slender, peg-like teeth that lack labial grooves and a ventrally deflected anteroventral margin of the dentary. This fossil is important because it is the only sauropod skull and jaw material recovered from the Jurassic of New Mexico, and one of less than a dozen Morrison Formation diplodocid skulls known. The preserved skull is too incomplete to assign to a specific genus, but the numerous sauropod postcrania from the locality should, when prepared, facilitate genus-level identification of the sauropods at the Peterson Quarry. Although some of the preserved teeth were clearly unerupted, the presence of over 30 teeth suggests that nearly the entire dentition was preserved, and recovery of additional sauropod teeth from the Peterson Quarry suggests that more sauropod skulls might be found there in the future.