Unlike mammals, the avian tongue has a bone in it. In this image the proximal end of the tongue is to the right, the
distal end to the left.
A typical synovial joint, complete with articular cartilages is visible; the articulation is at the proximal end of the mouth.
Both bones have a typical CT periosteum; skeletal muscles insert onto the short proximal bone opposite the articulation, and also on the ventral surface of the longer distal bone. At the very top edge of the field you can see some of the dorsal surface epithelium, heavily stained in comparison to the rest of the tissues.
The stiff avian tongue isn't used in vocalization to nearly the extent that the very mobile tongue of the mammal is. Its principal function is manipulating food.
Avian tongue, decalcified; H&E stain, paraffin section, 20x