2] is concave; it presents depressions corresponding to the cerebral convolutions, and numerous furrows (grooves) for the ramifications of the middle meningeal artery; the latter run upward and backward from the sphenoidal angle, and from the central and posterior part of the squamous border.

Ossification gradually extends in a radial manner from the center toward the margins of the bone; the angles are consequently the parts last formed, and it is here that the fontanelles exist.

Occasionally the parietal bone is divided into two parts, upper and lower, by an antero-posterior suture.

These frills, which overhang the neck and extend past the rest of the skull is a diagnostic trait of ceratopsians.

[4] This article incorporates text in the public domain from page 133 of the 20th edition of Gray's Anatomy (1918)