Birds have fused carpals and metacarpals. 8 Tarsals in the ankle are free with the exception of the fused third tarsal. Birds have fused tarsals. The bones are solid and lack pneumaticity, with the exception of the cervical and anterior vertebrae. The sternum was not bony or keeled, leaving no attachment point for flight muscles.
Birds have a bony sternum, but some birds lack a keel.
This may have been reported in some dinosaurs. The quadrate bone articulates with the braincase. This may be a general amniote condition. 15 Fused clavicles form the furcula. This has also been reported in some theropods.