 "Caenagnathus sternbergi", for example, was described on the basis of a jaw bone.It has been interpreted as either the jaws of "Chirostenotes pergracilis" (described on the basis of a pair of hands) or "Chirostenotes elegans" (described on the basis of a foot), but because no complete skeleton is known, it is difficult to be certain which animal it belongs to.The relationships of other species remain in doubt.