small parietal bone thin neurocranium thin parietal bone 2017-10-13T11:12:39Z MPheno.ontology reduced thickness of the paired membranous bones located between the frontal and occipital bones that are large, curved and quadrilateral in outline, articulate with each other at the midline in the sagittal suture, and form most of the superior and lateral aspects of the cranium MP:0030281 reduced parietal bone thickness thin parietal bones decreased parietal bone thickness decreased thickness of the tetrapod parietal bone