40 - Predicting Adult Primate Pterion Suture Patterns Through Newborn Cranial Bone Development

Poster Board Number: 40
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Abstract Body : The pterion is a region on the lateral skull where the zygomatic, frontal, parietal, sphenoid, and squamosal bones articulate. The pattern of sutures at pterion distinguishes New World (platyrrhine) and Old World (catarrhine) anthropoid primates. In humans and other catarrhines, the frontal bone articulates with the sphenoid. The parietal and zygomatic bones do not touch. In contrast, in platyrrhines, the parietal articulates with the zygomatic, and the frontal and sphenoid do not touch. There are many exceptions to this rule, and even within humans there are sutural variations at pterion. Scientific literature largely fails to identify the biological reason for the distinction between catarrhines and platyrrhines and the mechanism producing sutural variations at pterion.

We examined the crania of newborn primates using 3D virtual reconstructions from microCT scans to study comparative development of cranial bones. We also used diceCT imaging for a subset of the specimens to relate cranial bones to underlying regions of the brain. Three-dimensional models of the newborn primate skulls were constructed using 3D Slicer software and MeshLab. Quantifiable data included endocast volume and relative surface area of the bones involved at pterion: parietal bones, greater wings of the sphenoid, frontal, zygomatic, and squamous temporal. One of the most compelling results was the surface area of the parietal relative to that of the frontal bone. The parietal was significantly larger in platyrrhines than catarrhines. In contrast, catarrhines had more expansive frontal squama. This appears to relate to the relatively larger frontal lobes of the brain in this clade. We also observed relatively larger squamous temporals in the catarrhine sample, likely related to expanded temporal lobes. The timing and relative expansion of the frontal, squamous temporal, and alisphenoid versus the parietal bone appears to explain the difference observed in pterion patterns. Identifying the cause of these morphological differences has implications for anthropological, anatomy, neurosurgical, and zoological primate research due to pterion serving as a clinically and phylogenetically important landmark.

Funding provided by the National Science Foundation (BCS-1830894 and BCS-1830919)