The Experts below are selected from a list of 1788 Experts worldwide ranked by ideXlab platform
Dean Falk - One of the best experts on this subject based on the ideXlab platform.
-
First virtual reconstructions of the frontal lobe and temporal pole of the Taung (Australopithecus africanus) Endocast
2011Co-Authors: Dean Falk, Benoit Combes, Jose Braga, Gérard Subsol, Sylvain PrimaAbstract:The Taung type specimen for Australopithecus africanus includes a natural Endocast that reproduces external morphology of a large portion of the right cerebral hemisphere, and a separate fragment of the fossilized face that articulates with the Endocast. The natural Endocast lacks the right temporal pole and rostral part of the frontal lobes, which were embedded in the back of the facial fragment. Although these structures have previously been reconstructed manually using the external morphology of the facial fragment as a guide, we used advanced 3D-CT technology to prepare virtual reconstructions of the frontal lobes and right temporal pole. We then joined these parts of Taung's virtual Endocast to a virtual image of the natural Endocast, and reconstructed the remaining missing areas using mirror imaging. The resulting virtual Endocast of Taung was compared with 3D geometrical models of chimpanzee and bonobo Endocasts reconstructed from CT scans of dry skulls representing individuals at the same dental developmental age as Taung. We employed recently developed automated computational tools that allowed processing of 3D free-form surfaces and quantification of the mean anatomy within each species (chimpanzees and bonobos) as well as the pattern of variability around these means. These results were compared to those for Taung, and allowed us to test Raymond Dart's hypothesis that Taung's brain was advanced toward a human condition in the shape of its prefrontal as well as parieto-occipital association cortices. Our findings lend strength to Dart's suggestion that australopithecine brains evolved in a global rather than mosaic manner.
-
The natural Endocast of Taung (Australopithecus africanus): insights from the unpublished papers of Raymond Arthur Dart.
American Journal of Physical Anthropology, 2009Co-Authors: Dean FalkAbstract:Dart's 1925 announcement of Australopithecus africanus (Dart: Nature 115 [1925] 195–199) was highly controversial, partly because of an interpretation of the Taung natural Endocast that rested on an erroneous identification of the lambdoid suture as the lunate sulcus. Unpublished materials from the University of Witwatersrand Archives (Dart, unpublished material) reveal that Dart reacted to the controversy by: 1) describing and illustrating the entire sulcal pattern on the Taung Endocast, in contrast to just two sulcal identifications in 1925, 2) identifying a hypothetical part of the lambdoid suture and revising his description of the lunate sulcus, and 3) bolstering his argument that Taung's brain was advanced by detailing expansions in three significant cortical association areas. Four unpublished illustrations of Dart's identifications for sulci and sutures on the Taung Endocast are compared here with those published by Keith (Keith: New discoveries relating to the antiquity of man (1931)), Schepers (Schepers: The endocranial casts of the South African ape-men. In: Broom R, Schepers GWH, editors. The South African fossil ape-men; the Australopithecinae [1946] p 155–272), and Falk (Falk: Am J Phys Anthropol 53 [1980] 525–539), and the thorny issue of the location of the lunate sulcus is revisited in light of new information. Archival materials reveal that Dart believed that Taung's brain was reorganized globally rather than in a mosaic manner, and that the shapes of certain cortical association areas showed that Australopithecus was closer to Pithecanthropus than to the living apes. Although a few of Dart's hitherto-unpublished sulcal identifications, including his revision for the lunate sulcus, were questionable, his claim that the Taung Endocast reproduced a shape that was advanced toward a human condition in its prefrontal cortex and caudally protruded occipital lobe was correct. Yrbk Phys Anthropol 52:49–65, 2009. © 2009 Wiley-Liss, Inc.
-
The natural Endocast of Taung (Australopithecus africanus): insights from the unpublished papers of Raymond Arthur Dart.
American journal of physical anthropology, 2009Co-Authors: Dean FalkAbstract:Dart's 1925 announcement of Australopithecus africanus (Dart: Nature 115 [1925] 195-199) was highly controversial, partly because of an interpretation of the Taung natural Endocast that rested on an erroneous identification of the lambdoid suture as the lunate sulcus. Unpublished materials from the University of Witwatersrand Archives (Dart, unpublished material) reveal that Dart reacted to the controversy by: 1) describing and illustrating the entire sulcal pattern on the Taung Endocast, in contrast to just two sulcal identifications in 1925, 2) identifying a hypothetical part of the lambdoid suture and revising his description of the lunate sulcus, and 3) bolstering his argument that Taung's brain was advanced by detailing expansions in three significant cortical association areas. Four unpublished illustrations of Dart's identifications for sulci and sutures on the Taung Endocast are compared here with those published by Keith (Keith: New discoveries relating to the antiquity of man (1931)), Schepers (Schepers: The endocranial casts of the South African ape-men. In: Broom R, Schepers GWH, editors. The South African fossil ape-men; the Australopithecinae [1946] p 155-272), and Falk (Falk: Am J Phys Anthropol 53 [1980] 525-539), and the thorny issue of the location of the lunate sulcus is revisited in light of new information. Archival materials reveal that Dart believed that Taung's brain was reorganized globally rather than in a mosaic manner, and that the shapes of certain cortical association areas showed that Australopithecus was closer to Pithecanthropus than to the living apes. Although a few of Dart's hitherto-unpublished sulcal identifications, including his revision for the lunate sulcus, were questionable, his claim that the Taung Endocast reproduced a shape that was advanced toward a human condition in its prefrontal cortex and caudally protruded occipital lobe was correct.
-
Brief communication: new reconstruction of the Taung Endocast.
American Journal of Physical Anthropology, 2007Co-Authors: Dean Falk, Ronald J. ClarkeAbstract:Earlier reconstructions of the Taung Endocast, from the juvenile type specimen for Australopithecus africanus, were achieved without benefit of the advanced computer technology that is available today and before morphological differences were identified that distinguish Endocasts of Paranthropus from those of A. africanus. Here, we reconstruct and measure a relatively complete virtual Endocast of Taung and provide a new cranial capacity estimate of 382 cm(3) and a projected adult capacity of 406 cm(3), which are smaller than previous estimates. Linear measurements and ratios were also obtained from an Endocast of Sts 5 and five Paranthropus Endocasts and compared with those of Taung. A number of previously unrecognized foramina, processes, and canals are identified in the bony material that adheres to the base of the Taung Endocast. The newly reconstructed virtual Endocast of Taung displays a number of shape features that sort it more closely with gracile than robust australopithecines, including squared-off frontal lobes in dorsal view, and the shape of the tips of its temporal poles. The Taung Endocast also shares some features with Paranthropus Endocasts, while other characteristics such as small temporal lobes may be due to its juvenile status. Just how much of Taung's unique morphology is due to its juvenile status may eventually be clarified by comparing its Endocast with those from other juvenile australopithecines such as the 3.3-million-year-old juvenile from Dikika, Ethiopia.
-
early hominid brain evolution a new look at old Endocasts
Journal of Human Evolution, 2000Co-Authors: Dean Falk, John C Redmond, John Guyer, C Conroy, Wolfgang Recheis, Gerhard W Weber, Horst SeidlerAbstract:Early hominid brain morphology is reassessed from Endocasts of Australopithecus africanus and three species of Paranthropus, and new Endocast reconstructions and cranial capacities are reported for four key specimens from the Paranthropus clade. The brain morphology of Australopithecus africanus appears more human like than that of Paranthropus in terms of overall frontal and temporal lobe shape. These new data do not support the proposal that increased encephalization is a shared feature between Paranthropus and early Homo. Our findings are consistent with the hypothesis that Australopithecus africanus could have been ancestral to Homo, and have implications for assessing the tempo and mode of early hominid neurological and cognitive evolution.
Emmanuel Gilissen - One of the best experts on this subject based on the ideXlab platform.
-
The endocranial shape of Australopithecus africanus: surface analysis of the Endocasts of Sts 5 and Sts 60.
Journal of Anatomy, 2017Co-Authors: Amélie Beaudet, Emmanuel Gilissen, Jean Dumoncel, Gérard Subsol, Stanley Durrleman, Anna Catherina Oettle, Frikkie De Beer, John Francis Thackeray, Jose BragaAbstract:Assessment of global endocranial morphology and regional neuroanatomical changes in early hominins is critical for the reconstruction of evolutionary trajectories of cerebral regions in the human lineage. Early evidence of cortical reorganization in specific local areas (e.g. visual cortex, inferior frontal gyrus) is perceptible in the non-human South African hominin fossil record. However, to date, little information is available regarding potential global changes in the early hominin brain. The introduction of non-invasive imaging techniques opens up new perspectives for the study of hominin brain evolution. In this context, our primary aim in this study is to explore the organization of the Australopithecus africanus Endocasts, and highlight the nature and extent of the differences distinguishing A. africanus from the extant hominids at both local and global scales. By means of X-ray-based imaging techniques, we investigate two A. africanus specimens from Sterkfontein Member 4, catalogued as Sts 5 and Sts 60, respectively a complete cranium and a partial cranial Endocast. Endocrania were virtually reconstructed and compared by using a landmark-free registration method based on smooth and invertible surface deformation. Both local and global information provided by our deformation-based approach are used to perform statistical analyses and topological mapping of inter-specific variation. Statistical analyses indicate that the endocranial shape of Sts 5 and Sts 60 approximates the Pan condition. Furthermore, our study reveals substantial differences with respect to the extant human condition, particularly in the parietal regions. Compared with Pan, the endocranial shape of the fossil specimens differs in the anterior part of the frontal gyri.
-
virtual endocranial cast of earliest eocene diacodexis artiodactyla mammalia and morphological diversity of early artiodactyl brains
Proceedings of The Royal Society B: Biological Sciences, 2012Co-Authors: Maeva J Orliac, Emmanuel GilissenAbstract:The study of brain evolution, particularly that of the neocortex, is of primary interest because it directly relates to how behavioural variations arose both between and within mammalian groups. Artiodactyla is one of the most diverse mammalian clades. However, the first 10 Myr of their brain evolution has remained undocumented so far. Here, we used high-resolution X-ray computed tomography to investigate the endocranial cast of Diacodexis ilicis of earliest Eocene age. Its virtual reconstruction provides unprecedented access to both metric parameters and fine anatomy of the most complete Endocast of the earliest artiodactyl. This picture is assessed in a broad comparative context by reconstructing Endocasts of 14 other Early and Middle Eocene representatives of basal artiodactyls, allowing the tracking of the neocortical structure of artiodactyls back to its simplest pattern. We show that the earliest artiodactyls share a simple neocortical pattern, so far never observed in other ungulates, with an almond-shaped gyrus instead of parallel sulci as previously hypothesized. Our results demonstrate that artiodactyls experienced a tardy pulse of encephalization during the Late Neogene, well after the onset of cortical complexity increase. Comparisons with Eocene perissodactyls show that the latter reached a high level of cortical complexity earlier than the artiodactyls.
-
Digital cranial Endocast of Hyopsodus (Mammalia, "Condylarthra"): a case of paleogene terrestrial echolocation?
PLoS ONE, 2012Co-Authors: Maeva J Orliac, Christine C. Argot, Emmanuel GilissenAbstract:We here describe the endocranial cast of the Eocene archaic ungulate Hyopsodus lepidus AMNH 143783 (Bridgerian, North America) reconstructed from X-ray computed microtomography data. This represents the first complete cranial Endocast known for Hyopsodontinae. The Hyopsodus Endocast is compared to other known “condylarthran” Endocasts, i. e. those of Pleuraspidotherium (Pleuraspidotheriidae), Arctocyon (Arctocyonidae), Meniscotherium (Meniscotheriidae), Phenacodus (Phenacodontidae), as well as to basal perissodactyls (Hyracotherium) and artiodactyls (Cebochoerus, Homacodon). Hyopsodus presents one of the highest encephalization quotients of archaic ungulates and shows an “advanced version” of the basal ungulate brain pattern, with a mosaic of archaic characters such as large olfactory bulbs, weak ventral expansion of the neopallium, and absence of neopallium fissuration, as well as more specialized ones such as the relative reduction of the cerebellum compared to cerebrum or the enlargement of the inferior colliculus. As in other archaic ungulates, Hyopsodus midbrain exposure is important, but it exhibits a dorsally protruding largely developed inferior colliculus, a feature unique among “Condylarthra”. A potential correlation between the development of the inferior colliculus in Hyopsodus and the use of terrestrial echolocation as observed in extant tenrecs and shrews is discussed. The detailed analysis of the overall morphology of the postcranial skeleton of Hyopsodus indicates a nimble, fast moving animal that likely lived in burrows. This would be compatible with terrestrial echolocation used by the animal to investigate subterranean habitat and/or to minimize predation during nocturnal exploration of the environment.
Juan Ignacio Canale - One of the best experts on this subject based on the ideXlab platform.
-
Cranial Endocast of the carcharodontosaurid theropod Giganotosaurus carolinii Coria & Salgado, 1995
Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen, 2010Co-Authors: Ariana Paulina Carabajal, Juan Ignacio CanaleAbstract:A complete Endocast of Giganotosaurus carolinii CORIA & SALGADO, 1995 was made in latex after removing mechanically the sediment filling of the cerebral cavity of the braincase, thereby allowing the description of the endocranial anatomy of the specimen. The Endocast was compared with the other few known natural or artificial theropod Endocasts, including the two species of the African allosauroid species Carcharodontosaurus saharicus and C. idiguensis. As in Carcharodontosaurus, the olfactory bulbs in Giganotosaurus are aligned with the forebrain, the midbrain is posteroventrally inclined and the hindbrain is parallel but ventral to the forebrain, showing similarly angled cephalic and pontine flexures. The cranial nerves and blood vessels have a similar disposition as in Carcharodontosaurus saharicus. However, in Giganotosaurus there is only one branch for cranial nerve XII, and cranial nerve XI has a separate internal opening from the vagus foramen (metotic foramen). In C. saharicus, there is a separate opening as well, but it is anterior in position and was probably utilized by cranial nerve IX. The length of the Endocast of Giganotosaurus, including the olfactory bulbs, is approximately 19 % longer than the Endocast in Carcharodontosaurus saharicus.
-
cranial Endocast of the carcharodontosaurid theropod giganotosaurus carolinii coria salgado 1995
Neues Jahrbuch Fur Geologie Und Palaontologie-abhandlungen, 2010Co-Authors: Ariana Paulina Carabajal, Juan Ignacio CanaleAbstract:A complete Endocast of Giganotosaurus carolinii CORIA & SALGADO, 1995 was made in latex after removing mechanically the sediment filling of the cerebral cavity of the braincase, thereby allowing the description of the endocranial anatomy of the specimen. The Endocast was compared with the other few known natural or artificial theropod Endocasts, including the two species of the African allosauroid species Carcharodontosaurus saharicus and C. idiguensis. As in Carcharodontosaurus, the olfactory bulbs in Giganotosaurus are aligned with the forebrain, the midbrain is posteroventrally inclined and the hindbrain is parallel but ventral to the forebrain, showing similarly angled cephalic and pontine flexures. The cranial nerves and blood vessels have a similar disposition as in Carcharodontosaurus saharicus. However, in Giganotosaurus there is only one branch for cranial nerve XII, and cranial nerve XI has a separate internal opening from the vagus foramen (metotic foramen). In C. saharicus, there is a separate opening as well, but it is anterior in position and was probably utilized by cranial nerve IX. The length of the Endocast of Giganotosaurus, including the olfactory bulbs, is approximately 19 % longer than the Endocast in Carcharodontosaurus saharicus.
Peggy Vincent - One of the best experts on this subject based on the ideXlab platform.
-
Endocranial anatomy of plesiosaurians (Reptilia, Plesiosauria) from the Late Cretaceous (Turonian) of Goulmima (Southern Morocco)
Journal of Vertebrate Paleontology, 2019Co-Authors: Rémi Allemand, Nathalie Bardet, Alexandra Houssaye, Peggy VincentAbstract:Despite recent advances in noninvasive imaging, Plesiosauria remains one of the least explored clades of reptiles with respect to paleoneuroanatomy. Only partial Endocasts, obtained from either latex casts or imprints left on the braincase, have been described. In this contribution, the digital Endocasts of three plesiosaurian specimens were analyzed: two referred to the elasmosaurid Libonectes morgani and one to Polycotylidae indet., all from the Late Cretaceous (Turonian) of Goulmima (Morocco). They were computed tomography (CT)-scanned to provide new anatomical information on the plesiosaurian Endocast, endosseous labyrinth, and cranial nerves. Results show that the three Endocasts are very similar to each other. They appear anteroposteriorly elongated and horizontally oriented in lateral view, with long olfactory tracts, relatively small and incomplete olfactory bulbs, a reduced pineal organ, distinguishable optic lobes, and a possible large cerebellum constituting the main component in size of the Endocast. The endocranial features reconstructed here are compared with those of other plesiosaurians, as well as other marine reptiles, notably to discuss their intraspecific and interspecific variability. This study provides pioneer data in order to estimate the impact of both phylogenetic and ecological constraints on the endocranial morphology of plesiosaurians and proposes a few preliminary paleobiological suggestions.
-
Comparative morphology of snake (Squamata) Endocasts: evidence of phylogenetic and ecological signals.
Journal of Anatomy, 2017Co-Authors: Rémi Allemand, Renaud Boistel, Gheylen Daghfous, Zoé Blanchet, Raphaël Cornette, Nathalie Bardet, Peggy Vincent, Alexandra HoussayeAbstract:Brain Endocasts obtained from computed tomography (CT) are now widely used in the field of comparative neuroanatomy. They provide an overview of the morphology of the brain and associated tissues located in the cranial cavity. Through anatomical comparisons between species, insights on the senses, the behavior, and the lifestyle can be gained. Although there are many studies dealing with mammal and bird Endocasts, those performed on the brain Endocasts of squamates are comparatively rare, thus limiting our understanding of their morphological variability and interpretations. Here, we provide the first comparative study of snake brain Endocasts in order to bring new information about the morphology of these structures. Additionally, we test if the snake brain Endocast encompasses a phylogenetic and/or an ecological signal. For this purpose, the digital Endocasts of 45 snake specimens, including a wide diversity in terms of phylogeny and ecology, were digitized using CT, and compared both qualitatively and quantitatively. Snake Endocasts exhibit a great variability. The different methods performed from descriptive characters, linear measurements and the outline curves provided complementary information. All these methods have shown that the shape of the snake brain Endocast contains, as in mammals and birds, a phylogenetic signal but also an ecological one. Although phylogenetically related taxa share several similarities between each other, the brain Endocast morphology reflects some notable ecological trends: e.g. (i) fossorial species possess both reduced optic tectum and pituitary gland; (ii) both fossorial and marine species have cerebral hemispheres poorly developed laterally; (iii) cerebral hemispheres and optic tectum are more developed in arboreal and terrestrial species.
Jose Braga - One of the best experts on this subject based on the ideXlab platform.
-
The endocranial shape of Australopithecus africanus: surface analysis of the Endocasts of Sts 5 and Sts 60.
Journal of Anatomy, 2017Co-Authors: Amélie Beaudet, Emmanuel Gilissen, Jean Dumoncel, Gérard Subsol, Stanley Durrleman, Anna Catherina Oettle, Frikkie De Beer, John Francis Thackeray, Jose BragaAbstract:Assessment of global endocranial morphology and regional neuroanatomical changes in early hominins is critical for the reconstruction of evolutionary trajectories of cerebral regions in the human lineage. Early evidence of cortical reorganization in specific local areas (e.g. visual cortex, inferior frontal gyrus) is perceptible in the non-human South African hominin fossil record. However, to date, little information is available regarding potential global changes in the early hominin brain. The introduction of non-invasive imaging techniques opens up new perspectives for the study of hominin brain evolution. In this context, our primary aim in this study is to explore the organization of the Australopithecus africanus Endocasts, and highlight the nature and extent of the differences distinguishing A. africanus from the extant hominids at both local and global scales. By means of X-ray-based imaging techniques, we investigate two A. africanus specimens from Sterkfontein Member 4, catalogued as Sts 5 and Sts 60, respectively a complete cranium and a partial cranial Endocast. Endocrania were virtually reconstructed and compared by using a landmark-free registration method based on smooth and invertible surface deformation. Both local and global information provided by our deformation-based approach are used to perform statistical analyses and topological mapping of inter-specific variation. Statistical analyses indicate that the endocranial shape of Sts 5 and Sts 60 approximates the Pan condition. Furthermore, our study reveals substantial differences with respect to the extant human condition, particularly in the parietal regions. Compared with Pan, the endocranial shape of the fossil specimens differs in the anterior part of the frontal gyri.
-
3D automated quantification of asymmetries on fossil Endocasts
2016Co-Authors: Benoit Combes, Francis Thackeray, Jose Braga, Sylvain PrimaAbstract:Over the last 15 years computed tomography (CT) has become a common way to obtain high resolution three-dimensional images of cranial Endocast of hominids. Among the different features that can be seen on such Endocasts, of key interest are their shape asymmetries. In particular, protrusions of the frontal and occipital lobes, as well as differences in their width, have been typically observed in modern humans' brains. These have been often hypothesized to be linked to functional specialization, and especially language and handedness. The imprints of these protrusions on the inner surface of the skull are called the petalia. There is a lack of automated, reproducible and objective methods to quantify these protrusions and to assess (for instance) whether they are present in species other than Homo sapiens. We propose a new method for the automated quantification of 3D endocranial shape asymmetries. We mathematically define the symmetry plane of the Endocast as the 3D plane which best superposes the "right" and "left" sides of the endocranial surface. Then, we compute a 3D pointwise deformation field between the two sides of the Endocast, allowing to match homologous points, and to assess their relative spatial position. The analysis of this 3D deformation field allows quantifying the shape asymmetries everywhere on the Endocast. We illustrate our method on the Endocast of Sts 5 (Mrs. Ples, Australopithecus africanus) whose very high resolution CT scan has been segmented using ITK-SNAP. The results suggest an opposite shape asymmetry in the fronto-temporal and occipital regions.
-
New 3D automatic methods for the analysis of the endocranial shape and its relationship with ectocranial structures: assessment and preliminary experiments
2011Co-Authors: Sylvain Prima, Benoit Combes, Jose Braga, Gérard Subsol, Ralph Holloway, Tom Schoenemann, Janet MongeAbstract:Over these last years, new computerized methods have been proposed to build virtual Endocasts based on 3D CT images of extant or fossil skulls. This allows analyzing large samples automatically and then obtaining significant statistical results about the shape of the Endocast and its correlation relative to other anatomical structures. We assessed two new algorithms to segment and process virtual Endocasts. The first tool allows delineating the boundary of the 3D endocranial surface without any manual interaction, even in presence of large holes (such as the foramen magnum). We compared these virtual Endocasts with the corresponding plaster Endocasts manually casted by one the authors. The second algorithm allows the automated measurement of 3D asymmetry on the virtual Endocasts, and the computation of a mean 3D endocranial shape over several individuals on which the mean population asymmetry can be assessed. To show the potential of such automatic tools, we propose to study the relationship between the shape of the Endocast and the external shape of the skull. For this purpose, we selected about twenty dry skulls in the Morton collection. These skulls were selected from populational samples which have been considered in the past to evince pronounced exo-cranial secondary-developing super-structures. These samples were CT-scanned and we automatically segmented both the external surface of the skull and the Endocast. We present the first results of our analysis by focusing on the exocranial versus endocranial differences at the level of the neurocranium of each individual. We also compare asymmetry patterns between individuals.
-
Mapping the distance between the brain and the inner surface of the skull: interest for the study of fossil Endocasts
2011Co-Authors: Marc Fournier, Benoit Combes, Jose Braga, Neil Roberts, Sylvain PrimaAbstract:Endocranial casts are commonly used to infer the shape, size, asymmetry or overall organization of the brain of fossil species. However, Endocasts are only an indirect representation of the brain. Few studies seek to assess the faithfulness of this representation, upon which is based much of our knowledge on the evolution of the brain of hominids. The aim of this work is to automatically map in 3D the distance between the brain and the inner surface of the skull in humans and other primates to see how some morphological characteristics of the Endocast (and in particular its asymmetries) relate to those of the brain. MR images are used to automatically extract the brain and virtual Endocast. Point-to-point distances are evaluated between the two surfaces to generate a distance map. Bilateral asymmetries of the brain and virtual Endocast are also computed. A mean endocranial shape evaluation provides average distances and asymmetries maps. Results show that the local distance between the brain and the virtual Endocast strongly varies between anatomical regions, but symmetrically with respect to the mid-sagittal plane. It follows that global asymmetries of the brain and Endocast are closely related. These findings suggest that in paleoanthropology, the study of natural or virtual Endocasts gives significant information about the morphology of the brain of fossil species. Moreover, we may use the distance map computed on extant species to infer more precise information about the potential surface of the brain of fossil species.
-
First virtual reconstructions of the frontal lobe and temporal pole of the Taung (Australopithecus africanus) Endocast
2011Co-Authors: Dean Falk, Benoit Combes, Jose Braga, Gérard Subsol, Sylvain PrimaAbstract:The Taung type specimen for Australopithecus africanus includes a natural Endocast that reproduces external morphology of a large portion of the right cerebral hemisphere, and a separate fragment of the fossilized face that articulates with the Endocast. The natural Endocast lacks the right temporal pole and rostral part of the frontal lobes, which were embedded in the back of the facial fragment. Although these structures have previously been reconstructed manually using the external morphology of the facial fragment as a guide, we used advanced 3D-CT technology to prepare virtual reconstructions of the frontal lobes and right temporal pole. We then joined these parts of Taung's virtual Endocast to a virtual image of the natural Endocast, and reconstructed the remaining missing areas using mirror imaging. The resulting virtual Endocast of Taung was compared with 3D geometrical models of chimpanzee and bonobo Endocasts reconstructed from CT scans of dry skulls representing individuals at the same dental developmental age as Taung. We employed recently developed automated computational tools that allowed processing of 3D free-form surfaces and quantification of the mean anatomy within each species (chimpanzees and bonobos) as well as the pattern of variability around these means. These results were compared to those for Taung, and allowed us to test Raymond Dart's hypothesis that Taung's brain was advanced toward a human condition in the shape of its prefrontal as well as parieto-occipital association cortices. Our findings lend strength to Dart's suggestion that australopithecine brains evolved in a global rather than mosaic manner.