Leandro Aristide1,2, André Strauss3,4,5, Lauren B Halenar-Price6,7, Emmanuel Gilissen8,9, Francisco W Cruz10, Castor Cartelle11, Alfred L Rosenberger7,12, Ricardo T Lopes13, Sergio F Dos Reis14, S Ivan Perez1,15. 1. División Antropología (FCNyM-UNLP), CONICET, La Plata, Argentina. 2. Institut de biologie de l'Ecole normale supérieure (IBENS), Ecole normale supérieure, CNRS, INSERM, PSL Université Paris, Paris, France. 3. Museu de Arqueologia e Etnologia, Universidade de São Paulo, São Paulo, Brazil. 4. Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil. 5. Palaeoanthropology Senckenberg Centre for Human Evolution and Palaeoenvironment, Eberhard Karls Universität Tübingen, Tübingen, Germany. 6. Department of Biology, Farmingdale State College (SUNY), New York, New York. 7. NYCEP Morphometrics Group, New York, NY. 8. Department of African Zoology, Royal Museum for Central Africa, Tervuren, Belgium. 9. Laboratory of Histology and Neuropathology, Université Libre de Bruxelles, Brussels, Belgium. 10. Instituto de Geociências, Universidade de São Paulo, São Paulo, Brazil. 11. Museu de Ciências Naturais, Pontificia Universidade Católica de Minas Gerais, Belo Horizonte, Brazil. 12. Department of Anthropology, City of New York Graduate Center, New York, New York. 13. Laboratório de Instrumentação Nuclear, Centro de Tecnologia (UFRJ), Río de Janeiro, Brazil. 14. Instituto de Biologia Animal (UNICAMP), Campinas, Brazil. 15. Instituto de Física 'Gleb Wataghin' (UNICAMP), Campinas, Brazil.
Abstract
OBJECTIVES: Platyrrhines constitute a diverse clade, with the modern Atelidae exhibiting the most variation in cranial and endocast morphology. The processes responsible for this diversification are not well understood. Here, we present a geometric morphometric study describing variation in cranial and endocranial shape of 14 species of Alouatta, Ateles, Brachyteles, and Lagothrix and two extinct taxa, Cartelles and Caipora. METHODS: We examined cranial and endocranial shape variation among species using images reconstructed from CT scans and geometric morphometric techniques based on three-dimensional landmarks and semilandmarks. Principal components analyses were used to explore variation, including the Procrustes shape coordinates, summing the logarithm of the Centroid Size, the common allometric component, and residual shape components. RESULTS: Differences in endocranial shape are related to a relative increase or decrease in the volume of the neocortex region with respect to brainstem and cerebellum regions. The relative position of the brainstem varies from a posterior position in Alouatta to a more ventral position in Ateles. The shape of both the cranium and endocast of Caipora is within the observed variation of Brachyteles. Cartelles occupies the most differentiated position relative to the extant taxa, especially in regards to its endocranial shape. CONCLUSIONS: The pattern of variation in the extant species in endocranial shape is similar to the variation observed in previous cranial studies, with Alouatta as an outlier. The similarities between Caipora and Brachyteles were unexpected and intriguing given the frugivorous adaptations inferred from the fossil's dentition. Our study shows the importance of considering both extant and fossil species when studying diversification of complex traits.
OBJECTIVES:Platyrrhines constitute a diverse clade, with the modern Atelidae exhibiting the most variation in cranial and endocast morphology. The processes responsible for this diversification are not well understood. Here, we present a geometric morphometric study describing variation in cranial and endocranial shape of 14 species of Alouatta, Ateles, Brachyteles, and Lagothrix and two extinct taxa, Cartelles and Caipora. METHODS: We examined cranial and endocranial shape variation among species using images reconstructed from CT scans and geometric morphometric techniques based on three-dimensional landmarks and semilandmarks. Principal components analyses were used to explore variation, including the Procrustes shape coordinates, summing the logarithm of the Centroid Size, the common allometric component, and residual shape components. RESULTS: Differences in endocranial shape are related to a relative increase or decrease in the volume of the neocortex region with respect to brainstem and cerebellum regions. The relative position of the brainstem varies from a posterior position in Alouatta to a more ventral position in Ateles. The shape of both the cranium and endocast of Caipora is within the observed variation of Brachyteles. Cartelles occupies the most differentiated position relative to the extant taxa, especially in regards to its endocranial shape. CONCLUSIONS: The pattern of variation in the extant species in endocranial shape is similar to the variation observed in previous cranial studies, with Alouatta as an outlier. The similarities between Caipora and Brachyteles were unexpected and intriguing given the frugivorous adaptations inferred from the fossil's dentition. Our study shows the importance of considering both extant and fossil species when studying diversification of complex traits.
Authors: Paula N Gonzalez; Mariana Vallejo-Azar; Leandro Aristide; Ricardo Lopes; Sergio F Dos Reis; S Ivan Perez Journal: Brain Struct Funct Date: 2021-08-29 Impact factor: 3.270