Upper Triassic Tetrapods from the Lucero Uplift, Central New Mexico

Six localities in the lower Chinle Group of central New Mexico yield a tetrapod fauna consisting of the diminutive metoposaurid cf. Apachesaurus sp., and indeterminate large metoposaurids (probably Buettneria sp.), the phytosaur Rutiodon sp., indeterminate phytosaurs, the aetosaurs Desmatosuchus sp. and cf Stagonolepis sp., a probable theropod, and other, indeterminate archosaurs. Five of these localities are in the Bluewater Creek Formation, and yield all components of the Upper Triassic tetrapod fauna from the Lucero uplift (Lucero local fauna) except for an isolated scute of Desmatosuchus sp., recovered from the homotaxial San Pedro Arroyo Formation. Of the Bluewater Creek Formation tetrapods, the most complete specimen represents a large (4-m body length) phytosaur assigned to Rutiodon sp. and consists of a partial pelvis, an interclavicle, five articulated vertebrae, and numerous ribs. The remaining elements of this fauna closely resemble other faunas collected from the Bluewater Creek Formation. In particular, the abundance of metoposaurids and phytosaurs is similar to faunas in the Zuni Mountains in west-central New Mexico and the Blue Hills near 51. Johns, Arizona. The presence of the aetosaur cr. Stagonolepis sp. and the phytosaur Ruttodon sp., both of which are index taxa of the Adamanian land-vertebrate faunachron, indicates a latest Carnian age for the Lucero local fauna, an age assignment consistent with that of the Bluewater Creek Formation elsewhere. FIGURE 1. Outcrop distribution of Triassic strata in west-central New Mexico showing the position and large outcrop areas of the Lucero uplift. Modified from Stewart et al., 1972. and Lucas (1993a) summarized the known vertebrate fauna of the lower Chinle Group in the Lucero uplift, essentially reiterating the observations of Hunt et al. (1989). Lucas and Heckert (1994) identified a scute of the aetosaur Desmatosuchus from the San Pedro Arroyo Formation in the southern Lucero uplift. Following these reconnaissance efforts, the New Mexico Museum of Natural History and Science (NMMNH) initiated several collecting trips to the Lucero uplift in 1996 and 1997. Here, I document the results of these efforts, and provide a comprehensive faunal Est of the lower Chinle Group in the Lucero uplift that completely indexes all material collected there by parties of the NMMNH. I do this in part because existing documentation of these collections was never intended to be complete, but also because numerous nomenclatural changes have occurred since 1989, so that many of the taxonomic assignments made by Hunt et al. (1989) are out of dale,