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Allemand R, López-Aguirre C, Abdul-Sater J, Khalid W, Lang MM, Macrì S, Di-Poï N, Daghfous G, Silcox MT. A landmarking protocol for geometric morphometric analysis of squamate endocasts. Anat Rec (Hoboken) 2023; 306:2425-2442. [PMID: 36654187 DOI: 10.1002/ar.25162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 12/29/2022] [Accepted: 01/03/2023] [Indexed: 01/20/2023]
Abstract
Landmark-based geometric morphometrics is widely used to study the morphology of the endocast, or internal mold of the braincase, and the diversity associated with this structure across vertebrates. Landmarks, as the basic unit of such methods, are intended to be points of correspondence, selected depending on the question at hand, whose proper definition is essential to guarantee robustness and reproducibility of results. In this study, 20 landmarks are defined to provide a framework to analyze the morphological variability in squamate endocasts. Ten species representing a cross-section of the diversity of Squamata from both phylogenetic and ecological (i.e., habitat) perspectives were considered, to select landmarks replicable throughout the entire clade, regardless of the degree of neuroanatomical resolution of the endocast. To assess the precision, accuracy, and repeatability of these newly defined landmarks, both intraobserver and interobserver error were investigated. Estimates of measurement error show that most of the landmarks established here are highly replicable, and preliminary results suggest that they capture aspects of endocast shape related to both phylogenetic and ecologic signals. This study provides a basis for further examinations of squamate endocast disparity using landmark-based geometric morphometrics.
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Affiliation(s)
- Rémi Allemand
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Camilo López-Aguirre
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Jade Abdul-Sater
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Waqqas Khalid
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Madlen M Lang
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Simone Macrì
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Nicolas Di-Poï
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | | | - Mary T Silcox
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
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Allemand R, Abdul-Sater J, Macrì S, Di-Poï N, Daghfous G, Silcox MT. Endocast, brain, and bones: Correspondences and spatial relationships in squamates. Anat Rec (Hoboken) 2023; 306:2443-2465. [PMID: 36602153 DOI: 10.1002/ar.25142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 12/05/2022] [Accepted: 12/06/2022] [Indexed: 01/06/2023]
Abstract
Vertebrate endocasts are widely used in the fields of paleoneurology and comparative neuroanatomy. The validity of endocranial studies is dependent upon the extent to which an endocast reflects brain morphology. Due to the variable neuroanatomical resolution of vertebrate endocasts, direct information about the brain morphology can be sometimes difficult to assess and needs to be investigated across lineages. Here, we employ X-ray computed tomography (CT), including diffusible iodine-based contrast-enhanced CT, to qualitatively compare brains and endocasts in different species of squamates. The relative position of the squamate brain within the skull, as well as the variability that may exist in such spatial relationships, was examined to help clarify the neurological regions evidence on their endocasts. Our results indicate that squamate endocasts provide variable representation of the brain, depending on species and neuroanatomical regions. The olfactory bulbs and peduncles, cerebral hemispheres, as well as the medulla oblongata represent the most easily discernable brain regions from squamate endocasts. In contrast, the position of the optic lobes, the ventral diencephalon and the pituitary may be difficult to determine depending on species. Finally, squamate endocasts provide very limited or no information about the cerebellum. The spatial relationships revealed here between the brain and the surrounding bones may help to identify each of the endocranial region. However, as one-to-one correspondences between a bone and a specific region appear limited, the exact delimitation of these regions may remain challenging according to species. This study provides a basis for further examination and interpretation of squamate endocast disparity.
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Affiliation(s)
- Rémi Allemand
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Jade Abdul-Sater
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
| | - Simone Macrì
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Nicolas Di-Poï
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | | | - Mary T Silcox
- Department of Anthropology, University of Toronto Scarborough, Toronto, Ontario, Canada
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Gonzalez PN, Vallejo-Azar M, Aristide L, Lopes R, Dos Reis SF, Perez SI. Endocranial asymmetry in New World monkeys: a comparative phylogenetic analysis of morphometric data. Brain Struct Funct 2021; 227:469-477. [PMID: 34455496 DOI: 10.1007/s00429-021-02371-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 08/23/2021] [Indexed: 11/25/2022]
Abstract
Brain lateralization is a widespread phenomenon although its expression across primates is still controversial due to the reduced number of species analyzed and the disparity of methods used. To gain insight into the diversification of neuroanatomical asymmetries in non-human primates we analyze the endocasts, as a proxy of external brain morphology, of a large sample of New World monkeys and test the effect of brain size, home range and group sizes in the pattern and magnitude of shape asymmetry. Digital endocasts from 26 species were obtained from MicroCT scans and a set of 3D coordinates was digitized on endocast surfaces. Results indicate that Ateles, Brachyteles, Callicebus and Cacajao tend to have a rightward frontal and a leftward occipital lobe asymmetry, whereas Aotus, Callitrichinae and Cebinae have either the opposite pattern or no directional asymmetry. Such differences in the pattern of asymmetry were associated with group and home range sizes. Conversely, its magnitude was significantly associated with brain size, with larger-brained species showing higher inter-hemispheric differences. These findings support the hypothesis that reduction in inter-hemispheric connectivity in larger brains favors the lateralization and increases the structural asymmetries, whereas the patterns of shape asymmetry might be driven by socio-ecological differences among species.
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Affiliation(s)
- Paula N Gonzalez
- Unidad Ejecutora de Estudios en Neurociencias y Sistemas Complejos (CONICET-UNAJ-HEC), Florencio Varela, Buenos Aires, Argentina.
| | - Mariana Vallejo-Azar
- Unidad Ejecutora de Estudios en Neurociencias y Sistemas Complejos (CONICET-UNAJ-HEC), Florencio Varela, Buenos Aires, Argentina
| | | | - Ricardo Lopes
- Centro de Tecnologia (UFRJ), Laboratório de Instrumentação Nuclear, Rio de Janeiro, Brazil
| | | | - S Ivan Perez
- División Antropología (FCNyM-UNLP), CONICET, La Plata, Argentina
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Fontoura E, Ferreira JD, Bubadué J, Ribeiro AM, Kerber L. Virtual brain endocast of Antifer (Mammalia: Cervidae), an extinct large cervid from South America. J Morphol 2020; 281:1223-1240. [PMID: 32815595 DOI: 10.1002/jmor.21243] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 06/23/2020] [Accepted: 07/17/2020] [Indexed: 01/22/2023]
Abstract
A diverse fossil record of Cervidae (Mammalia) has been documented in the South American Pleistocene, when these animals arrived during the Great American Biotic Interchange. Using computed tomography-scanning techniques, it is possible to access the endocranial morphology of extinct species. Here, we studied the brain endocast of the extinct late Pleistocene cervid Antifer ensenadensis from southern Brazil, one of the largest forms that lived on this continent, using comparative morphology, geometric morphometrics, and encephalization quotients. The analyzed endocasts demonstrate that A. ensenadensis had a gyrencephalic brain, showing a prominent longitudinal sinus (=sagittal superior sinus), which is also observed in the large South American cervid Blastocerus dichotomus. The encephalization quotient is within the variation of extant cervids, suggesting maintenance of the pattern of encephalization from at least the late Pleistocene. Geometric morphometric analysis suggested a clear and linear allometric trend between brain endocast size and shape, and highlights A. ensenadensis as an extreme form within the analyzed cervids regarding brain morphology.
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Affiliation(s)
- Emmanuelle Fontoura
- Programa de Pós-Graduação em Biodiversidade Animal, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Brazil.,Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, São João do Polêsine, Brazil
| | - José Darival Ferreira
- Programa de Pós-Graduação em Biodiversidade Animal, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Brazil.,Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, São João do Polêsine, Brazil
| | - Jamile Bubadué
- Programa de Pós-Graduação em Biodiversidade Animal, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Brazil.,Laboratório de Ciências Ambientais, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Brazil
| | - Ana Maria Ribeiro
- Seção de Paleontologia, Museu de Ciências Naturais, Secretaria do Meio Ambiente e Infraestrutura, Porto Alegre, Brazil
| | - Leonardo Kerber
- Programa de Pós-Graduação em Biodiversidade Animal, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, Brazil.,Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, São João do Polêsine, Brazil.,Museu Paraense Emílio Goeldi, Coordenação de Ciências da Terra e Ecologia, Belém, Brazil
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The Evolutionary Radiation of Hominids: a Phylogenetic Comparative Study. Sci Rep 2019; 9:15267. [PMID: 31649259 PMCID: PMC6813319 DOI: 10.1038/s41598-019-51685-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 10/07/2019] [Indexed: 11/09/2022] Open
Abstract
Over the last 150 years the diversity and phylogenetic relationships of the hominoids have been one of the main focuses in biological and anthropological research. Despite this, the study of factors involved in their evolutionary radiation and the origin of the hominin clade, a key subject for the further understanding of human evolution, remained mostly unexplored. Here we quantitatively approach these events using phylogenetic comparative methods and craniofacial morphometric data from extant and fossil hominoid species. Specifically, we explore alternative evolutionary models that allow us to gain new insights into this clade diversification process. Our results show a complex and variable scenario involving different evolutionary regimes through the hominid evolutionary radiation –modeled by Ornstein-Uhlenbeck multi-selective regime and Brownian motion multi-rate scenarios–. These different evolutionary regimes might relate to distinct ecological and cultural factors previously suggested to explain hominid evolution at different evolutionary scales along the last 10 million years.
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