Improved conodont biostratigraphic constraint of the Carboniferous/Permian boundary in south-central New Mexico, USA.

Recovery of P1 elements of Streptognathodus isolatus and associated nodose streptognathodids from the Laborcita Member of the Bursum Formation near Tularosa, New Mexico clarifies placement of the Carboniferous/Permian boundary in the northern SacramentoMountains. Conodont elements, fish teeth, and dermal plates are abundant in a thin (4.8m) highstand carbonate succession located approximately 70 m above the base of the 130 m-thick Laborcita Member. The fauna represents the oldest Permian conodonts discovered thus far inNew Mexico and in a basin associated with theAncestral RockyMountains orogen. The occurrence of S. isolatus in this tectonic and geographic setting further demonstrates its utility in defining and correlating the base of the Permian System on a global scale. Occurring with S. isolatus in earliest Asselian strata is S. barricki n. sp., which is described herein. [ABSTRACT FROM AUTHOR]