Association of the chondrocranium and dermatocranium in early skull formation

Kazuhiko Kawasaki, Joan T. Richtsmeier

Research output: Chapter in Book/Report/Conference proceedingChapter

27 Scopus citations


Terminology for the branchial/visceral/pharyngeal arches, and for the skull in general, grew out of a number of distinct anatomic and paleontologic traditions and suffers from a lack of cohesion. Depew et al. (2002) Introduction Studies of the skull have long played a fundamental role in anthropological research and many studies support the idea that major changes in the cranial base have played crucial roles in the evolution of early primates, in the origin of anthropoids, and in the origin of Homo sapiens (Scott, 1958; Lieberman et al., 2000). The cranial base angle, measured on the sagittal plane according to various designs (McCarthy, 2001), is a measure of the relationship between the anterior (prechordal) and the posterior (parachordal) cranial base and is thought to be key to elucidating developmental and evolutionary events as evidenced in the association of cranial base morphology and skull form (Lieberman et al., 2008). Studies of the influence of brain size and shape on cranial base morphology has a long history in anthropological theory (Lieberman et al., 2000), prompting ideas like the spatial packing hypothesis (Biegert, 1963), which states that basicranial flexion in haplorhines maximizes braincase volume relative to basicranial length, and has motivated recent studies designed to test the hypothesis that a relatively larger brain is accommodated by a more flexed cranial base in anthropoids (Ross and Ravosa, 1993; Ross and Henneberg, 1995; Spoor, 1997; McCarthy, 2001). Additional hypotheses proposed to account for variation in the cranial base angle in primates (and specifically for the increased flexion in Homo sapiens) include: that basicranial flexion is an adaptation to repositioning of the foramen magnum to place the center of mass of the head over the axial skeleton (the postural hypothesis) and reduce stresses on the rostral portion of the cranial base; that flexion accommodates a more globular brain that minimizes the distances between neurons thereby facilitating cognitive function; and that flexion accommodates hyolaryngeal descent permitting quantal speech (see McCarthy, 2001 for a detailed list of references to research that has tested these hypotheses). The cranial base angle has served as a surrogate metric for complex cranial base morphology that can now be measured without difficulty using 3D imaging methods or digitizers.

Original languageEnglish (US)
Title of host publicationBuilding Bones
Subtitle of host publicationBone Formation and Development in Anthropology
PublisherCambridge University Press
Number of pages27
ISBN (Electronic)9781316388907
ISBN (Print)9781107122789
StatePublished - Jan 1 2017

All Science Journal Classification (ASJC) codes

  • General Social Sciences


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