title: Eye Size and Set in Small-Bodied Fossil Primates: A Three-Dimensional Method.
abstract: We introduce a new method to geometrically reconstruct eye volume and placement in small-bodied primates based on the three-dimensional contour of the intraorbital surface. We validate it using seven species of living primates, with dry skulls and wet dissections, and test its application on seven species of Paleogene fossils of interest. The method performs well even when the orbit is damaged and incomplete, lacking the postorbital bar and represented only by the orbital floor. Eye volume is an important quantity for anatomic and metabolic reasons, which due to differences in eye set, or position within (or outside) the bony orbit, can be underestimated in living and fossil forms when calculated from aperture diameter. Our Ectopic Index quantifies how much the globe's volume protrudes anteriorly from the aperture. Lemur, Notharctus and Rooneyia resemble anthropoids, with deeply recessed eyes protruding 11%-13%. Galago and Tarsius are the other extreme, at 47%-56%. We argue that a laterally oriented aperture has little to do with line-of-sight in euprimates, as large ectopic eyes can position the cornea to enable a directly forward viewing axis, and soft tissue positions the eyes facing forward in megachiropteran bats, which have unenclosed, open eye sockets. The size and set of virtual eyes reconstructed from 3D cranial models confirm that eyes were large to hypertrophic in Hemiacodon, Necrolemur, Microchoerus, Pseudoloris and Shoshonius, but eye size in Rooneyia may have been underestimated by measuring the aperture, as in Aotus. Anat Rec, 299:1671-1689, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Department of Anthropology and Archaeology, Brooklyn College, City University of New York, Brooklyn, New York.|New York Consortium in Evolutionary Primatology (NYCEP), Department of Anthropology, The Graduate Center, City University of New York, New York, New York.|Department of Mammalogy, American Museum of Natural History, New York, New York.
authors.forename: Alfred L
authors.initials: AL
authors.lastname: Rosenberger
authors.affiliation: School of Physical Therapy, Slippery Rock University, Slippery Rock, Pennsylvania.|Department of Anthropology, University of Pittsburgh, Pittsburgh, Pennsylvania.
authors.forename: Tim D
authors.initials: TD
authors.lastname: Smith
authors.affiliation: Department of Anthropology, University of Florida, Gainesville, Florida.
authors.forename: Valerie B
authors.initials: VB
authors.lastname: DeLeon
authors.affiliation: Department of Physical Therapy, Duquesne University, Pittsburgh, Pennsylvania.
authors.forename: Anne M
authors.initials: AM
authors.lastname: Burrows
authors.affiliation: Earth and Environmental Sciences, CUNY Graduate Center, New York, New York.
authors.forename: Robert
authors.initials: R
authors.lastname: Schenck
authors.affiliation: Department of Biology, Farmingdale State College (SUNY), Farmingdale, New York.|New York Consortium in Evolutionary Primatology Morphometrics Group (NMG), City University of New York, New York, New York.
authors.forename: Lauren B
authors.initials: LB
authors.lastname: Halenar
mesh_terms: D000818:Animals; D005075:Biological Evolution; D005123:Eye / Q000033:anatomy & histology*; D005580:Fossils; D009915:Orbit / Q000033:anatomy & histology*; D011323:Primates / Q000033:anatomy & histology*; D012886:Skull / Q000033:anatomy & histology*
keywords: 3D reconstruction; Rooneyia; fossil primates; orbits; virtual eyes