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Unveiling the neuroanatomy of Josephoartigasia monesi and the evolution of encephalization in caviomorph rodents


Ferreira, José Darival; Rinderknecht, Andrés; de Moura Bubadué, Jamile; Gasparetto, Luiza Flores; Dozo, Maria Teresa; Sánchez-Villagra, Marcelo R; Kerber, Leonardo (2024). Unveiling the neuroanatomy of Josephoartigasia monesi and the evolution of encephalization in caviomorph rodents. Brain Structure & Function, 229(4):971-985.

Abstract

Abstract
Caviomorph rodents are an exceptional model for studying the effects of ecological factors and size relations on brain evolution. These mammals are not only speciose and ecologically diverse but also present wide body size disparity, especially when considering their fossil relatives. Here, we described the brain anatomy of the largest known rodent, Josephoartigasia monesi, uncovering distinctive features within this species regarding other taxa. Albeit resembling extant pacarana Dinomys branickii, J. monesi stands out due to its longer olfactory tract and well-developed sagittal sinus. Challenging the previous hypothesis that giant rodents possessed comparatively smaller brains, we found that J. monesi and another giant extinct rodent, Neoepiblema acreensis, are within the encephalization range of extant caviomorphs. This was unraveled while developing the a Phylogenetic Encephalization Quotient (PEQ) for Caviomorpha. With PEQ, we were able to trace brainsize predictions more accurately, accounting for species-shared ancestry while adding the extinct taxa phenotypic diversity into the prediction model. According to our results, caviomorphs encephalization patterns are not the product of ecological adaptations, and brain allometry is highly conservative within the clade. We challenge future studies to investigate caviomorphs encephalization within different taxonomic ranks while increasing the sampled taxa diversity, especially of extinct forms, in order to fully comprehend the magnitude of this evolutionary stasis.
Keywords Adaptive regimes · Allometric trends · Brain evolution · Cranial endocast · South America

Abstract

Abstract
Caviomorph rodents are an exceptional model for studying the effects of ecological factors and size relations on brain evolution. These mammals are not only speciose and ecologically diverse but also present wide body size disparity, especially when considering their fossil relatives. Here, we described the brain anatomy of the largest known rodent, Josephoartigasia monesi, uncovering distinctive features within this species regarding other taxa. Albeit resembling extant pacarana Dinomys branickii, J. monesi stands out due to its longer olfactory tract and well-developed sagittal sinus. Challenging the previous hypothesis that giant rodents possessed comparatively smaller brains, we found that J. monesi and another giant extinct rodent, Neoepiblema acreensis, are within the encephalization range of extant caviomorphs. This was unraveled while developing the a Phylogenetic Encephalization Quotient (PEQ) for Caviomorpha. With PEQ, we were able to trace brainsize predictions more accurately, accounting for species-shared ancestry while adding the extinct taxa phenotypic diversity into the prediction model. According to our results, caviomorphs encephalization patterns are not the product of ecological adaptations, and brain allometry is highly conservative within the clade. We challenge future studies to investigate caviomorphs encephalization within different taxonomic ranks while increasing the sampled taxa diversity, especially of extinct forms, in order to fully comprehend the magnitude of this evolutionary stasis.
Keywords Adaptive regimes · Allometric trends · Brain evolution · Cranial endocast · South America

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Paleontology
Dewey Decimal Classification:560 Fossils & prehistoric life
Scopus Subject Areas:Health Sciences > Anatomy
Life Sciences > General Neuroscience
Health Sciences > Histology
Uncontrolled Keywords:Histology, General Neuroscience, Anatomy
Language:English
Date:19 March 2024
Deposited On:25 Apr 2024 06:24
Last Modified:30 Jun 2024 01:41
Publisher:Springer
ISSN:1863-2653
OA Status:Closed
Publisher DOI:https://doi.org/10.1007/s00429-024-02762-y
PubMed ID:38502332
Project Information:
  • : FunderFP7
  • : Grant ID100016
  • : Project TitleCESAR - Cost-Efficient Methods and Processes for Safety Relevant Embedded Systems
  • : FunderFundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
  • : Grant ID
  • : Project Title