Jaw and tongue features in Psittaciformes and other orders with special reference to the anatomy of the Tooth‐billed pigeon (Didunculus strigirostris)

The parrot (Psittaciformes) show many highly distinctive features of head morphology. Jaw and tongue musculature have been investigated in seven other orders, for most of which parrot affinities have been postulated. The functional properties and evolution of various modifications found in parrots are discussed. Several features seen in the Tooth‐billed pigeon (Didunculus strigirostris) show a significant trend towards conditions in parrots, favouring the view that the Columbiformes are the order mostly closely related to the Psittaciformes. These features also set Didunculus apart from other pigeons, and it is strongly urged that it be given full family rank.