 Caenagnathids persisted up until the end of the Cretaceous period, as shown by the presence of at least two species in the late Maastrichtian Hell Creek Formation, before vanishing at the end of the Cretaceous along with all other non-avian dinosaurs.The family Caenagnathidae, together with its sister group the Oviraptoridae, comprises the superfamily Caenagnathoidea.In phylogenetic taxonomy, the clade Caenagnathidae is defined as the most inclusive group containing "Chirostenotes pergracilis" but not "Oviraptor philoceratops".