title: Toward Understanding the Mammalian Zygoma: Insights From Comparative Anatomy, Growth and Development, and Morphometric Analysis.
abstract: The zygoma, or jugum, is a cranial element that was present in Mesozoic tetrapods, well before the appearance of mammals. Although as an entity the zygoma is a primitive retention among mammals, it has assumed myriad configurations as this group diversified. As the zygoma is located at the intersection of the visual, respiratory, and masticatory apparatuses, it is potentially of great importance in systematic, phylogenetic, and functional studies focused on this region. For example, the facial component of the zygoma and its contribution to a postorbital bar (POB) appear to be relevant to the systematics of a number of mammalian subclades, and the formation of a bony postorbital septum (POS) that separates the orbit from the infratemporal fossa is unique to, and thus potentially phylogenetically significant for uniting anthropoid primates, while the zygoma itself appears to serve to resist tension and bending forces during mastication. In order to better understand the zygoma in the context of its contributions to the circumorbital region, we documented its morphological expression in specimens representing 10 orders of mammals. Since the presence of a POB and of a POS has long been used to justify uniting extant primates and anthropoid primates as respective clades, and because postorbital closure (POC) is morphologically more complex than a POB, we provide detail necessary to address these claims. Our taxically broad overview also allowed us to provide for the first time definitions of configurations that can be applied to future studies. Using a different, but also taxically broad sample of mammals, and of primates in particular, we performed two geometric morphometric analyses that were geared toward testing long-held interpretations of the functional role of the zygoma, especially with regard to mastication and in the context of orbital frontation (to which the zygoma contributes). Further, overall, zygomatic morphology tends not to scale with allometry, sexual dimorphism, or angle of orbital convergence, but it does contribute to unique patterns of intraspecies variation. Anat Rec, 300:76-151, 2017. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Department of Cell Biology, SUNY Downstate Medical Center, New York, New York.|Department of Otolaryngology, SUNY Downstate Medical Center, New York, New York.
authors.forename: Samuel
authors.initials: S
authors.lastname: Márquez
authors.affiliation: Department of Cell Biology, New York University School of Medicine, New York, New York.
authors.forename: Anthony S
authors.initials: AS
authors.lastname: Pagano
authors.affiliation: Department of Anthropology, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Schwartz
authors.affiliation: Department of Mammalogy, American Museum of Natural History, New York, New York.
authors.forename: Abigail
authors.initials: A
authors.lastname: Curtis
authors.affiliation: Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Bradley N
authors.initials: BN
authors.lastname: Delman
authors.affiliation: Department of Otolaryngology, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: William
authors.initials: W
authors.lastname: Lawson
authors.affiliation: Department of Otolaryngology, Icahn School of Medicine at Mount Sinai, New York, New York.|Center of Anatomy and Functional Morphology, Icahn School of Medicine at Mount Sinai, New York, New York.|Department of Medical Education, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Jeffrey T
authors.initials: JT
authors.lastname: Laitman
mesh_terms: D000717:Anatomy, Comparative; D000818:Animals; D008322:Mammals / Q000033:anatomy & histology*; D009915:Orbit / Q000033:anatomy & histology; D010802:Phylogeny; D012886:Skull / Q000033:anatomy & histology*; D015050:Zygoma / Q000033:anatomy & histology*
keywords: anthropodea; geometrics morphometric; mammals; postorbital bar; zygoma