Morphology and systematics of a new fossil snake from the early Rupelian (Oligocene) White River Formation, Wyoming.

The article focuses on the identification and description of a new extinct snake taxon, *Hibernophis breithaupti* gen. et sp. nov., from the early Oligocene White River Formation in Wyoming, USA. Based on four nearly complete and articulated fossil snakes, detailed morphological and phylogenetic analyses distinguish *Hibernophis* from previously assigned North American fossil "erycine" vertebral form taxa such as *Ogmophis* and *Calamagras*. Phylogenetic results place *Hibernophis* as a basal member of Booidea, a major clade within constricting snakes (Constrictores), although an alternative placement within Charinaidae close to New World "erycines" and ungaliophiines cannot be statistically rejected. This discovery provides rare cranial and postcranial data that contribute to understanding the early evolution and biogeography of Booidea in North America during the Oligocene.