title: Cerebral complexity preceded enlarged brain size and reduced olfactory bulbs in Old World monkeys.
abstract: Analysis of the only complete early cercopithecoid (Old World monkey) endocast currently known, that of 15-million-year (Myr)-old Victoriapithecus, reveals an unexpectedly small endocranial volume (ECV) relative to body size and a large olfactory bulb volume relative to ECV, similar to extant lemurs and Oligocene anthropoids. However, the Victoriapithecus brain has principal and arcuate sulci of the frontal lobe not seen in the stem catarrhine Aegyptopithecus, as well as a distinctive cercopithecoid pattern of gyrification, indicating that cerebral complexity preceded encephalization in cercopithecoids. Since larger ECVs, expanded frontal lobes, and reduced olfactory bulbs are already present in the 17- to 18-Myr-old ape Proconsul these features evolved independently in hominoids (apes) and cercopithecoids and much earlier in the former. Moreover, the order of encephalization and brain reorganization was apparently different in hominoids and cercopithecoids, showing that brain size and cerebral organization evolve independently.
authors.affiliation: Department of Evolutionary Anthropology, Duke University, 104 Biological Sciences Building, Box 90383, Durham, North Carolina 27708-9976, USA.
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Gonzales
authors.affiliation: Department of Anthropology, New Mexico State University, PO Box 30001, Las Cruces, New Mexico 88003-8001, USA.
authors.forename: Brenda R
authors.initials: BR
authors.lastname: Benefit
authors.affiliation: Department of Anthropology, New Mexico State University, PO Box 30001, Las Cruces, New Mexico 88003-8001, USA.
authors.forename: Monte L
authors.initials: ML
authors.lastname: McCrossin
authors.affiliation: 1] Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig 04103, Germany [2] Department of Cell and Developmental Biology, UCL, Gower Street, London WC1E 6BT, UK.
authors.forename: Fred
authors.initials: F
authors.lastname: Spoor
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002520:Cercopithecidae; D054022:Cerebrum / Q000033:anatomy & histology; D005580:Fossils / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D005625:Frontal Lobe / Q000033:anatomy & histology*; D015186:Hominidae; D009830:Olfactory Bulb / Q000033:anatomy & histology*; D009929:Organ Size; D012886:Skull / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed