Borioteiioidean lizards skulls from Kleskun Hill (Wapiti Formation; Upper Campanian), west-central Alberta, Canada

New material of borioteiioidean lizards (Squamata: Scincomorpha) from west-central Alberta, Canada, represent the first and northernmost record of multiple articulated skull elements from the Cretaceous of North America. Specimens were recovered from the fluvial beds of the Wapiti Formation (Campanian) within a bentonitic paleosol exposed at the Kleskun Hill Park, east of the city of Grande Prairie. Such beds accumulated during the maximum transgression of the Bearpaw Seaway (73–74 Ma), thus providing crucial information on lizard faunas during a time interval represented in most of coeval North American deposits by marine strata. Cranial material ascribed to Socognathus unicuspis give the occasion for a revision of the taxon with respect to osteologically better-known Polyglyphanodon sternbergi from the Late Cretaceous of Utah as well as a comparison with several lizards reported from coeval strata of Mongolia. Furthermore, a new scincomorphan lizard, Kleskunsaurus grandeprairiensis, gen. et sp. nov., is described. Socognathus unicuspis is assigned to Chamopsiidae, taxon nov., which also includes Chamops, Leptochamops, and several other morphologically similar taxa from the Cretaceous of North America.