New Mexico Geological Society Annual Spring Meeting — Abstracts

The Bull Canyon Formation (Upper Triassic: Revueltian) of east-central New Mexico and West Texas contains the most diverse Late Triassic dinosaur fauna in the world. The majority of dinosaur specimens represent theropods, but several omithischian and prosauropod specimens are known.

Omithischian dinosaurs are represented by at least three taxa. Revueltosaurus callenderi Hunt, 1989 is known from five localities in the lower (R1) portion of the formation. R. callenderi is the most abundant herbivorous dinosaur in the Bull Canyon Formation although it is only known from isolated teeth. Technosaurus smalli Chatterjee, 1984 is a second R1 omithischian represented by a dentulous dentary from one locality. New Mexico Museum of Natural History specimen NMMNH P-17483 is a portion of a proximal femur with a prominent fourth trochanter. This specimen represents a small omithischian in the R1 portion of the Bull Canyon Formation. It could represent a juvenile of R. callenderi or T. smalli or a separate small taxon. Lucianosaurus wildi Hunt and Lucas, 1993 is only known from one locality in the upper (R2) portion of the formation and is represented by isolated teeth.

Prosauropods are poorly represented in the Bull Canyon Formation. The R1 fauna includes only an indeterminate premaxilla and a lower jaw fragment. The R2 fauna includes one dorsal centrum and a number of isolated teeth.

In conclusion, the lower R1 fauna of the Bull Canyon Formation includes R. callenderi, T. smalli, a possible third omithischian and an indeterminate prosauropod and the upper R2 fauna includes L. wildi and an indeterminate prosauropod.