 While before 2010s only about two to six species were commonly recognized as belonging to the Caenagnathidae, currently that number may be much greater, with new discoveries and theories about older species that may inflate this number to up to ten.Much of this historical difference centers on the first caenagnathid to be described, "Chirostenotes pergracilis".Due to the poor preservation of most caenagnathid remains and resulting misidentifications, different bones and different specimens of "Chirostenotes" have historically been assigned to a number of different species.