One last bone from the lower jaw got incorporated into the ear structure. This dome encloses the inner and middle ears. In development of middle ear, the spiracular pouch of the embryo forms the ...

ii. With loss of bones, switch to bones articulating hinge between upper and lower jaw. Amphibian, reptile: quadrate (upper) and articular (lower) jaw form hinge. 2 small bones form hinge: not very ...