LAUSR

Abstract A diverse microfauna from the lower shale of the Aguja Formation of West Texas records a rare, early Campanian assemblage of fossil squamates from North America. This assemblage is comprised of scincomorph, anguimorph, and ophidian taxa and is the most inclusive of its kind thus far described from the southern faunal province of Laramidia. Among numerous taxa described herein, three (Hypostylos lehmani gen. et sp. nov., Bothriagenys flectomendax sp. nov., and Hydrargysaurus gladius gen. et sp. nov) pertain to new scincomorphs which dominate the assemblage; however, subordinate anguimorphs are also well-represented. Snakes are represented by a single taxon, aff. Coniophis; a species seemingly ubiquitous throughout most Campanian strata in the southern Western Interior. Comparison among squamate assemblages from similar coastal facies in the upper shale of the Aguja Formation as well as the paracontemporaneous Wahweap and Kaiparowits formations of southern Utah reveals patterns of biogeographic segregation among some lizard species and the presence of two distinct communities. These two ‘southern’ squamate faunas are likely the result of variables involving climate and eustacy which facilitated diversity as well as the development of sub-provincial quarters of endemism during early-middle Campanian time.