The upper teeth form gomphoses with the bones:

The answer to this question would be: Maxilla

Gomphoses is a kind of joint that gives no movement. The bone that located upper of the teeth is maxilla bone. This bone is the one who responsible for the shape of the cheeck. On the lower teeth, the gomphoses should be made with mandible bone.

Spherical shaped cell might increase the surface area and decrease the volume.

A) early horses is your answer