title: Morphoarchitectural variation in South African fossil cercopithecoid endocasts.
abstract: Despite the abundance of well-preserved crania and natural endocasts in the South African Plio-Pleistocene cercopithecoid record, which provide direct information relevant to the evolution of their endocranial characteristics, few studies have attempted to characterize patterns of external brain morphology in this highly successful primate Superfamily. The availability of non-destructive penetrating radiation imaging systems, together with recently developed computer-based analytical tools, allow for high resolution virtual imaging and modeling of the endocranial casts and thus disclose new perspectives in comparative paleoneurology. Here, we use X-ray microtomographic-based 3D virtual imaging and quantitative analyses to investigate the endocranial organization of 14 cercopithecoid specimens from the South African sites of Makapansgat, Sterkfontein, Swartkrans, and Taung. We present the first detailed comparative description of the external neuroanatomies that characterize these Plio-Pleistocene primates. Along with reconstruction of endocranial volumes, we combine a semi-automatic technique for extracting the neocortical sulcal pattern together with a landmark-free surface deformation method to investigate topographic differences in morphostructural organization. Besides providing and comparing for the first time endocranial volume estimates of extinct Plio-Pleistocene South African cercopithecoid taxa, we report additional information regarding the variation in the sulcal pattern of Theropithecus oswaldi subspecies, and notably of the central sulcus, and the neuroanatomical condition of the colobine taxon Cercopithecoides williamsi, suggested to be similar for some aspects to the papionin pattern, and discuss potential phylogenetic and taxonomic implications. Further research in virtual paleoneurology, applied to specimens from a wider geographic area, is needed to clarify the polarity, intensity, and timing of cortical surface evolution in cercopithecoid lineages.
authors.affiliation: Department of Anatomy, University of Pretoria, PO Box 2034, Pretoria 0001, South Africa; Laboratoire d'Anthropologie Moléculaire et Imagerie de Synthèse, UMR 5288 CNRS-Université de Toulouse (Paul Sabatier), 37 Allées Jules Guesde, 31073 Toulouse Cedex 3, France. Electronic address: beaudet.amelie@gmail.com.
authors.forename: Amélie
authors.initials: A
authors.lastname: Beaudet
authors.affiliation: Laboratoire d'Anthropologie Moléculaire et Imagerie de Synthèse, UMR 5288 CNRS-Université de Toulouse (Paul Sabatier), 37 Allées Jules Guesde, 31073 Toulouse Cedex 3, France; Institut de Recherche en Informatique de Toulouse, UMR 5505 CNRS-Université de Toulouse (Paul Sabatier), 118 Route de Narbonne, 31062 Toulouse Cedex 9, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Dumoncel
authors.affiliation: Radiation Science Department, South African Nuclear Energy Corporation, Pelindaba, North West Province, South Africa.
authors.forename: Frikkie
authors.initials: F
authors.lastname: de Beer
authors.affiliation: Centre Inter-universitaire de Recherche et d'Ingénierie des Matériaux, UMR 5085 CNRS-Université de Toulouse (Paul Sabatier), 118 Route de Narbonne, 31062 Toulouse Cedex 9, France.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Duployer
authors.affiliation: Aramis Team, INRIA Paris, Sorbonne Universités, UPMC Université Paris 06 UMR S 1127, Inserm U 1127, CNRS UMR 7225, Institut du Cerveau et de la Moelle épinière, 47 boulevard de l'hôpital, 75013 Paris, France.
authors.forename: Stanley
authors.initials: S
authors.lastname: Durrleman
authors.affiliation: Department of African Zoology, Royal Museum for Central Africa, Leuvensesteenweg, 3080 Tervuren, Belgium; Laboratory of Histology and Neuropathology, Université Libre de Bruxelles, 1070 Brussels, Belgium.
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Gilissen
authors.affiliation: Radiation Science Department, South African Nuclear Energy Corporation, Pelindaba, North West Province, South Africa.
authors.forename: Jakobus
authors.initials: J
authors.lastname: Hoffman
authors.affiliation: Centre Inter-universitaire de Recherche et d'Ingénierie des Matériaux, UMR 5085 CNRS-Université de Toulouse (Paul Sabatier), 118 Route de Narbonne, 31062 Toulouse Cedex 9, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Tenailleau
authors.affiliation: Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Private Bag 3, Wits, 2050 Johannesburg, South Africa.
authors.forename: John Francis
authors.initials: JF
authors.lastname: Thackeray
authors.affiliation: Laboratoire d'Anthropologie Moléculaire et Imagerie de Synthèse, UMR 5288 CNRS-Université de Toulouse (Paul Sabatier), 37 Allées Jules Guesde, 31073 Toulouse Cedex 3, France; Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Private Bag 3, Wits, 2050 Johannesburg, South Africa.
authors.forename: José
authors.initials: J
authors.lastname: Braga
mesh_terms: D000353:Africa, Southern; D000818:Animals; D005075:Biological Evolution; D001921:Brain / Q000033:anatomy & histology*; D002521:Cercopithecus / Q000033:anatomy & histology* / Q000145:classification; D005580:Fossils / Q000033:anatomy & histology*; D021621:Imaging, Three-Dimensional; D012886:Skull / Q000033:anatomy & histology*; D016671:Theropithecus / Q000033:anatomy & histology* / Q000145:classification; D055114:X-Ray Microtomography
keywords: Cercopithecoides; Deformation-based models; Endocranial organization; Old World monkey taxonomy; Plio-Pleistocene; Theropithecus