 The bony-toothed birds' attachment of the coronoideal part of the external mandible adductor muscles was located at the midline, the rostropterygoid process had a support at its base and the mesethmoid bone had a deep depression for the caudal concha, just as in waterfowl.As regards other parts of the skeleton, the proposed synapomorphies of pelagornithids and waterfowl are found mainly in the arm- and handbones