Bone does not present at bih is

*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 doesn't occur until after bih. Reference: I B Singh&;s Embryology, 10th edition, pg 368