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Labra N, Mounier A, Leprince Y, Rivière D, Didier M, Bardinet E, Santin MD, Mangin JF, Filippo A, Albessard‐Ball L, Beaudet A, Broadfield D, Bruner E, Carlson KJ, Cofran Z, Falk D, Gilissen E, Gómez‐Robles A, Neubauer S, Pearson A, Röding C, Zhang Y, Balzeau A. What do brain endocasts tell us? A comparative analysis of the accuracy of sulcal identification by experts and perspectives in palaeoanthropology. J Anat 2024; 244:274-296. [PMID: 37935387 PMCID: PMC10780157 DOI: 10.1111/joa.13966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 10/12/2023] [Accepted: 10/12/2023] [Indexed: 11/09/2023] Open
Abstract
Palaeoneurology is a complex field as the object of study, the brain, does not fossilize. Studies rely therefore on the (brain) endocranial cast (often named endocast), the only available and reliable proxy for brain shape, size and details of surface. However, researchers debate whether or not specific marks found on endocasts correspond reliably to particular sulci and/or gyri of the brain that were imprinted in the braincase. The aim of this study is to measure the accuracy of sulcal identification through an experiment that reproduces the conditions that palaeoneurologists face when working with hominin endocasts. We asked 14 experts to manually identify well-known foldings in a proxy endocast that was obtained from an MRI of an actual in vivo Homo sapiens head. We observe clear differences in the results when comparing the non-corrected labels (the original labels proposed by each expert) with the corrected labels. This result illustrates that trying to reconstruct a sulcus following the very general known shape/position in the literature or from a mean specimen may induce a bias when looking at an endocast and trying to follow the marks observed there. We also observe that the identification of sulci appears to be better in the lower part of the endocast compared to the upper part. The results concerning specific anatomical traits have implications for highly debated topics in palaeoanthropology. Endocranial description of fossil specimens should in the future consider the variation in position and shape of sulci in addition to using models of mean brain shape. Moreover, it is clear from this study that researchers can perceive sulcal imprints with reasonably high accuracy, but their correct identification and labelling remains a challenge, particularly when dealing with extinct species for which we lack direct knowledge of the brain.
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Affiliation(s)
- Nicole Labra
- Département Homme et EnvironnementUMR 7194, CNRS, PaleoFED Team, Muséum national d’Histoire naturelleParisFrance
| | - Aurélien Mounier
- Département Homme et EnvironnementUMR 7194, CNRS, PaleoFED Team, Muséum national d’Histoire naturelleParisFrance
- Turkana Basin InstituteNairobiKenya
| | - Yann Leprince
- Université Paris‐Saclay, CEA, CNRS UMR 9027, Baobab, NeuroSpinGif‐sur‐YvetteFrance
| | - Denis Rivière
- Université Paris‐Saclay, CEA, CNRS UMR 9027, Baobab, NeuroSpinGif‐sur‐YvetteFrance
| | - Mélanie Didier
- ICM—Institut du Cerveau, Hôpital Pitié‐Salpêtrière, Centre de NeuroImagerie de Recherche—CENIRParisFrance
| | - Eric Bardinet
- ICM—Institut du Cerveau, Hôpital Pitié‐Salpêtrière, Centre de NeuroImagerie de Recherche—CENIRParisFrance
| | - Mathieu D. Santin
- ICM—Institut du Cerveau, Hôpital Pitié‐Salpêtrière, Centre de NeuroImagerie de Recherche—CENIRParisFrance
| | - Jean François Mangin
- Université Paris‐Saclay, CEA, CNRS UMR 9027, Baobab, NeuroSpinGif‐sur‐YvetteFrance
| | - Andréa Filippo
- Département Homme et EnvironnementUMR 7194, CNRS, PaleoFED Team, Muséum national d’Histoire naturelleParisFrance
| | - Lou Albessard‐Ball
- Département Homme et EnvironnementUMR 7194, CNRS, PaleoFED Team, Muséum national d’Histoire naturelleParisFrance
- Department of ArchaeologyPalaeoHub, University of YorkYorkUK
| | - Amélie Beaudet
- Laboratoire de Paléontologie, Évolution, Paléoécosystèmes et Paléoprimatologie (PALEVOPRIM), UMR 7262 CNRSUniversité de PoitiersPoitiersFrance
| | | | - Emiliano Bruner
- Paleobiología, Centro Nacional de Investigación sobre la Evolución HumanaBurgosSpain
| | - Kristian J. Carlson
- Evolutionary Studies InstituteUniversity of the Witwatersrand, Palaeosciences CentreJohannesburgSouth Africa
- Department of Integrative Anatomical Sciences, Keck School of MedicineUniversity of Southern CaliforniaCaliforniaLos AngelesUSA
| | - Zachary Cofran
- Anthropology DepartmentVassar CollegePoughkeepsieNew YorkUSA
| | - Dean Falk
- Department of AnthropologyFlorida State UniversityTallahasseeFloridaUSA
| | - Emmanuel Gilissen
- Department of African ZoologyRoyal Museum for Central AfricaTervurenBelgium
| | | | - Simon Neubauer
- Institute of Anatomy and Cell BiologyJohannes Kepler University LinzLinzAustria
| | - Alannah Pearson
- School of Archaeology and AnthropologyAustralian National UniversityCanberraAustralian Capital TerritoryAustralia
| | - Carolin Röding
- Paleoanthropology, Institute for Archaeological Sciences and Senckenberg Centre for Human Evolution and PaleoenvironmentEberhard Karls University of TübingenTübingenGermany
| | - Yameng Zhang
- Institute of Cultural HeritageShandong UniversityQingdaoShandongChina
| | - Antoine Balzeau
- Département Homme et EnvironnementUMR 7194, CNRS, PaleoFED Team, Muséum national d’Histoire naturelleParisFrance
- Department of African ZoologyRoyal Museum for Central AfricaTervurenBelgium
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Pusch LC, Kammerer CF, Fröbisch J. Cranial anatomy of the early cynodont Galesaurus planiceps and the origin of mammalian endocranial characters. J Anat 2019; 234:592-621. [PMID: 30772942 DOI: 10.1111/joa.12958] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/16/2019] [Indexed: 12/19/2022] Open
Abstract
The cranial anatomy of the early non-mammalian cynodont Galesaurus planiceps from the South African Karoo Basin is redescribed on the basis of a computed tomographic reconstruction of the skull. Previously, little was known about internal skull morphology and the nervous and sensory system of this taxon. The endocranial anatomy of various cynodonts has been intensively studied in recent years to understand the origin of mammalian characters in the nasal capsule, brain and ear. However, these studies have focused on only a few taxa, the earliest of which is another Early Triassic cynodont, Thrinaxodon liorhinus. Galesaurus is phylogenetically stemward of Thrinaxodon and thus provides a useful test of whether the mammal-like features observed in Thrinaxodon were present even more basally in cynodont evolution. The cranial anatomy of G. planiceps is characterized by an intriguing mosaic of primitive and derived features within cynodonts. In contrast to the very similar internal nasal and braincase morphology of Galesaurus and Thrinaxodon, parts of the skull that seem to be fairly conservative in non-prozostrodont cynodonts, the morphology of the maxillary canal differs markedly between these taxa. Unusually, the maxillary canal of Galesaurus has relatively few ramifications, more similar to those of probainognathian cynodonts than that of Thrinaxodon. However, its caudal section is very short, a primitive feature shared with gorgonopsians and therocephalians. The otic labyrinth of Galesaurus is generally similar to that of Thrinaxodon, but differs in some notable features (e.g. proportional size of the anterior semicircular canal). An extremely large, protruding paraflocculus of the brain and a distinct medioventrally located notch on the anterior surface of the tabular, which forms the dorsal border of the large parafloccular lobe, are unique to Galesaurus among therapsids with reconstructed endocasts. These features may represent autapomorphies of Galesaurus, but additional sampling is needed at the base of Cynodontia to test this.
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Affiliation(s)
- Luisa C Pusch
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany.,Institut für Biologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Christian F Kammerer
- North Carolina Museum of Natural Sciences, Raleigh, NC, USA.,Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Jörg Fröbisch
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany.,Institut für Biologie, Humboldt-Universität zu Berlin, Berlin, Germany.,Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
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Allemand R, Boistel R, Daghfous G, Blanchet Z, Cornette R, Bardet N, Vincent P, Houssaye A. Comparative morphology of snake (Squamata) endocasts: evidence of phylogenetic and ecological signals. J Anat 2017; 231:849-868. [PMID: 28960295 DOI: 10.1111/joa.12692] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/14/2017] [Indexed: 12/22/2022] Open
Abstract
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.
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Affiliation(s)
- Rémi Allemand
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, CR2P - UMR 7207 - CNRS, MNHN, UPMC, Muséum National d'Histoire Naturelle, Sorbonne Universités, Paris, France.,Département Adaptations du Vivant, UMR 7179 - CNRS/Muséum National d'Histoire Naturelle, Paris, France
| | - Renaud Boistel
- IPHEP-UMR CNRS 6046, UFR SFA, Université de Poitiers, Poitiers, France
| | - Gheylen Daghfous
- Groupe de Recherche sur le Système Nerveux Central, Département de Neurosciences, Université de Montréal, Montréal, QC, Canada
| | - Zoé Blanchet
- Département Adaptations du Vivant, UMR 7179 - CNRS/Muséum National d'Histoire Naturelle, Paris, France
| | - Raphaël Cornette
- Institut de Systématique, Evolution, Biodiversité, ISYEB - UMR 7205 - CNRS, MNHN, UPMC, EPHE, Muséum National d'Histoire Naturelle, Sorbonne Universités, Paris, France
| | - Nathalie Bardet
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, CR2P - UMR 7207 - CNRS, MNHN, UPMC, Muséum National d'Histoire Naturelle, Sorbonne Universités, Paris, France
| | - Peggy Vincent
- Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, CR2P - UMR 7207 - CNRS, MNHN, UPMC, Muséum National d'Histoire Naturelle, Sorbonne Universités, Paris, France
| | - Alexandra Houssaye
- Département Adaptations du Vivant, UMR 7179 - CNRS/Muséum National d'Histoire Naturelle, Paris, France
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