<prompt> Bone does not present at bih isMalleusIncusStapesPetrous temporal  <response>: Malleus and incus - derived from the dorsal end of Meckel;s cailage Stapes - from the dorsal end of the cailage of the second pharyngeal arch. The ear ossicles ossify fully in the 4th month of IUL - 1st bones in the body to do so. The mastoid process is not present at bih and stas developing at end of the first year and reaches its adult size at pubey. Mastoid antrum is an air-filled sinus within petrous pa of temporal bone. Development of the mastoid air cell system doesnt occur until after bih. Reference: I B Singh;s Embryology, 10th edition, pg 368 