title: Developmental and Evolutionary Significance of the Zygomatic Bone.
abstract: The zygomatic bone is derived evolutionarily from the orbital series. In most modern mammals the zygomatic bone forms a large part of the face and usually serves as a bridge that connects the facial skeleton to the neurocranium. Our aim is to provide information on the contribution of the zygomatic bone to variation in midfacial protrusion using three samples; humans, domesticated dogs, and monkeys. In each case, variation in midface protrusion is a heritable trait produced by one of three classes of transmission: localized dysmorphology associated with single gene dysfunction, selective breeding, or long-term evolution from a common ancestor. We hypothesize that the shape of the zygomatic bone reflects its role in stabilizing the connection between facial skeleton and neurocranium and consequently, changes in facial protrusion are more strongly reflected by the maxilla and premaxilla. Our geometric morphometric analyses support our hypothesis suggesting that the shape of the zygomatic bone has less to do with facial protrusion. By morphometrically dissecting the zygomatic bone we have determined a degree of modularity among parts of the midfacial skeleton suggesting that these components have the ability to vary independently and thus can evolve differentially. From these purely morphometric data, we propose that the neural crest cells that are fated to contribute to the zygomatic bone experience developmental cues that distinguish them from the maxilla and premaxilla. The spatiotemporal and molecular identity of the cues that impart zygoma progenitors with their identity remains an open question that will require alternative data sets. Anat Rec, 299:1616-1630, 2016. © 2016 The Authors The Anatomical Record Published by Wiley Periodicals, Inc.
authors.affiliation: UMR5199 PACEA, Bordeaux Archaeological Sciences Cluster of Excellence, Université De Bordeaux.
authors.forename: Yann
authors.initials: Y
authors.lastname: Heuzé
authors.affiliation: Department of Anthropology, Pennsylvania State University, University Park, PA.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Kawasaki
authors.affiliation: Department of Veterinary Clinical Studies, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Veterinary Centre, Roslin, Midlothian, UK.
authors.forename: Tobias
authors.initials: T
authors.lastname: Schwarz
authors.affiliation: Division of Genetics and Genomics, The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, UK.
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Schoenebeck
authors.affiliation: Department of Anthropology, Pennsylvania State University, University Park, PA.
authors.forename: Joan T
authors.initials: JT
authors.lastname: Richtsmeier
mesh_terms: D000818:Animals; D005075:Biological Evolution; D004285:Dogs; D005145:Face / Q000033:anatomy & histology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008437:Maxilla / Q000033:anatomy & histology; D015050:Zygoma / Q000033:anatomy & histology*
keywords: FGFR-related craniosynostosis syndromes; New World monkeys; Old World monkeys; domesticated dogs; midfacial hypoplasia; midfacial retrusion; prognathism