First occurrence of Doswellia cf. D. kaltenbachi (Archosauriformes) from the Late Triassic (middle Norian) Chinle Formation of Arizona and its implications on proposed biostratigraphic correlations across North America during the Late Triassic

Abstract

ABSTRACT Doswellia kaltenbachi is a long-snouted non-archosaur archosauriform known from the Late Triassic of the United States (Virginia and Texas). New material from the Chinle Formation of Arizona represents the first occurrence of D. cf. D. kaltenbachi from that formation and state. This occurrence is from the type section for the Adamanian estimated holochronozone (Late Triassic: middle Norian) in Petrified Forest National Park and firmly establishes the presence of this taxon in the Adamanian. This occurrence adds to the diverse vertebrate assemblage of the upper part of the Blue Mesa Member of the Chinle Formation (Adamanian). More broadly, the new occurrence strengthens biogeographic links to the older (latest Carnian or earliest Norian) Otischalkian from Texas and the possibly older Sanfordian/Conewagian assemblages of Virginia. The spatiotemporal distribution of Doswellia underscores the similarity of North American continental vertebrate assemblages across the Carnian–Norian boundary prior to the Adamanian–Revueltian boundary.