Upper Triassic tetrapods from the Lucero uplift, central New Mexico

Abstract

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.