Welman has argued that the quadrate of "Protoavis" displays synapomorphies of Theropoda. Paul has demonstrated the drepanosaur affinities of the cervical vertebrae. Gauthier & Rowe, and Dingus & Rowe have argued convincingly for identifying the hind limb of "Protoavis" as belonging to a ceratosaur. Feduccia has argued that "Protoavis" represents an arboreal "thecodont". In a study of early ornithischian dinosaurs, Sterling Nesbitt and others determined some of the partial remains of "Protoavis" to be a non-tetanuran theropod. The entire skull and neck are considered to be most likely from a drepanosaurid because the skull and neck are too big compared to the dorsal vertebrae of "Protoavis".