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Fonseca PHM, Martinelli AG, Gill PG, Rayfield EJ, Schultz CL, Kerber L, Ribeiro AM, Soares MB. Anatomy of the maxillary canal of Riograndia guaibensis (Cynodontia, Probainognathia)-A prozostrodont from the Late Triassic of southern Brazil. Anat Rec (Hoboken) 2024. [PMID: 39039851 DOI: 10.1002/ar.25540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 06/24/2024] [Accepted: 07/02/2024] [Indexed: 07/24/2024]
Abstract
Investigating the evolutionary trajectory of synapsid sensory and cephalic systems is pivotal for understanding the emergence and diversification of mammals. Recent studies using CT-scanning to analyze the rostral foramina and maxillary canals morphology in fossilized specimens of probainognathian cynodonts have contributed to clarifying the homology and paleobiological interpretations of these structures. In the present work, μCT-scannings of three specimens of Riograndia guaibensis, an early Norian cynodont from southern Brazil, were analyzed and revealed an incomplete separation between the lacrimal and maxillary canals, with points of contact via non-ossified areas. While the maxillary canal exhibits a consistent morphological pattern with other Prozostrodontia, featuring three main branches along the lateral region of the snout, the rostral alveolar canal in Riograndia displays variability in the number of extra branches terminating in foramina on the lateral surface of the maxilla, showing differences among individuals and within the same skull. Additionally, pneumatization is observed in the anterior region of the skull, resembling similar structures found in reptiles and mammals. Through this pneumatization, certain branches originating from the maxillary canal extend to the canine alveolus. Further investigation is warranted to elucidate the functionality of this structure and its occurrence in other cynodont groups.
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Affiliation(s)
- Pedro Henrique Morais Fonseca
- Programa de Pós-Graduação em Geociências, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Agustín Guillermo Martinelli
- CONICET-Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires, Argentina
- Núcleo Milenio EVOTEM-Evolutionary Transitions of Early Mammals-ANID, Santiago, Chile
| | - Pamela G Gill
- Palaeobiology Research Group, School of Earth Sciences, University of Bristol, Life Sciences Building, Bristol, UK
- Earth Sciences Department, The Natural History Museum, London, UK
| | - Emily J Rayfield
- Palaeobiology Research Group, School of Earth Sciences, University of Bristol, Life Sciences Building, Bristol, UK
| | - Cesar Leandro Schultz
- Programa de Pós-Graduação em Geociências, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Leonardo Kerber
- Centro de Apoio à Pesquisa Paleontológica, Universidade Federal de Santa Maria, São João do Polêsine, Brazil
| | - Ana Maria Ribeiro
- Programa de Pós-Graduação em Geociências, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Seção de Paleontologia, Museu de Ciências Naturais, Secretaria do Meio Ambiente e Infraestrutura do Rio Grande do Sul, Porto Alegre, Brazil
| | - Marina Bento Soares
- Departamento de Geologia e Paleontologia, Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Benoit J, Araujo R, Lund ES, Bolton A, Lafferty T, Macungo Z, Fernandez V. Early synapsids neurosensory diversity revealed by CT and synchrotron scanning. Anat Rec (Hoboken) 2024. [PMID: 38600433 DOI: 10.1002/ar.25445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 03/17/2024] [Accepted: 03/18/2024] [Indexed: 04/12/2024]
Abstract
Non-mammaliaform synapsids (NMS) represent the closest relatives of today's mammals among the early amniotes. Exploring their brain and nervous system is key to understanding how mammals evolved. Here, using CT and Synchrotron scanning, we document for the first time three extreme cases of neurosensory and behavioral adaptations that probe into the wide range of unexpected NMS paleoneurological diversity. First, we describe adaptations to low-frequency hearing and low-light conditions in the non-mammalian cynodont Cistecynodon parvus, supporting adaptations to an obligatory fossorial lifestyle. Second, we describe the uniquely complex and three-dimensional maxillary canal morphology of the biarmosuchian Pachydectes elsi, which suggests that it may have used its cranial bosses for display or low-energy combat. Finally, we introduce a paleopathology found in the skull of Moschognathus whaitsi. Since the specimen was not fully grown, this condition suggests the possibility that this species might have engaged in playful fighting as juveniles-a behavior that is both social and structured. Additionally, this paper discusses other evidence that could indicate that tapinocephalid dinocephalians were social animals, living and interacting closely with one another. Altogether, these examples evidence the wide range of diversity of neurological structures and complex behavior in NMS.
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Affiliation(s)
- J Benoit
- Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - R Araujo
- Instituto de Plasmas e Fusão Nuclear, InstitutoSuperior Técnico, Universidade de Lisboa, Lisboa, Portugal
| | - E S Lund
- Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - A Bolton
- Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - T Lafferty
- Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Z Macungo
- Evolutionary Studies Institute and School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - V Fernandez
- European Synchrotron Radiation Facility, Grenoble, France
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3
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Laaß M, Kaestner A. Nasal turbinates of the dicynodont Kawingasaurus fossilis and the possible impact of the fossorial habitat on the evolution of endothermy. J Morphol 2023; 284:e21621. [PMID: 37585231 DOI: 10.1002/jmor.21621] [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: 11/20/2022] [Revised: 06/28/2023] [Accepted: 06/29/2023] [Indexed: 08/17/2023]
Abstract
The nasal region of the fossorial anomodont Kawingasaurus fossilis was virtually reconstructed from neutron-computed tomographic data and compared with the terrestrial species Pristerodon mackayi and other nonmammalian synapsids. The tomography of the Kawingasaurus skull reveals a pattern of maxillo-, naso-, fronto- and ethmoturbinal ridges that strongly resemble the mammalian condition. On both sides of the nasal cavity, remains of scrolled maxilloturbinals were preserved that were still partially articulated with maxilloturbinal ridges. Furthermore, possible remains of the lamina semicircularis as well as fronto- or ethmoturbinals were found. In Kawingasaurus, the maxilloturbinal ridges were longer and stronger than in Pristerodon. Except for the nasoturbinal ridges, no other ridges in the olfactory region and no remains of turbinates were recognized. This supports the hypothesis that naso-, fronto-, ethmo- and maxilloturbinals were a plesiomorphic feature of synapsids, but due to their cartilaginous nature in most taxa were, in almost all cases, not preserved. The well-developed maxilloturbinals in Kawingasaurus were probably an adaptation to hypoxia-induced hyperventilation in the fossorial habitat, maintaining the high oxygen demands of Kawingasaurus' large brain. The surface area of the respiratory turbinates in Kawingasaurus falls into the mammalian range, which suggests that they functioned as a countercurrent exchange system for thermoregulation and conditioning of the respiratory airflow. Our results suggest that the environmental conditions of the fossorial habitat led to specific sensory adaptations, accompanied by a pulse in brain evolution and of endothermy in cistecephalids, ~50 million years before the origin of endothermy in the mammalian stem line. This supports the Nocturnal Bottleneck Theory, in that we found evidence for a similar evolutionary scenario in cistecephalids as proposed for early mammals.
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Affiliation(s)
- Michael Laaß
- Fakultät für Geowissenschaften, Geotechnik und Bergbau, TU Bergakademie Freiberg, Freiberg, Germany
- FRM II and Physics E21, Technische Universität München, Garching, Germany
| | - Anders Kaestner
- Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, Villigen PSI, Switzerland
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Benoit J, Norton LA, Jirah S. The maxillary canal of the titanosuchid Jonkeria (Synapsida, Dinocephalia). THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2023; 110:27. [PMID: 37272962 PMCID: PMC10241669 DOI: 10.1007/s00114-023-01853-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 05/13/2023] [Accepted: 05/15/2023] [Indexed: 06/06/2023]
Abstract
The maxillary canal of the titanosuchid dinocephalian Jonkeria is described based on digitised serial sections. We highlight that its morphology is more like that of the tapinocephalid Moschognathus than that of Anteosaurus. This is unexpected given the similarities between the dentition of Jonkeria and Anteosaurus (i.e., presence of a canine) and the fact that the branching pattern of the maxillary canal in synapsids usually co-varies with dentition. Hypotheses to account for similarities between Jonkeria and Moschognathus (common ancestry, function in social signalling or underwater sensing) are discussed. It is likely that the maxillary canal carries a strong phylogenetic signal, here supporting the clade Tapinocephalia.
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Affiliation(s)
- Julien Benoit
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.
| | - Luke A Norton
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Sifelani Jirah
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
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At the root of the mammalian mind: The sensory organs, brain and behavior of pre-mammalian synapsids. PROGRESS IN BRAIN RESEARCH 2023; 275:25-72. [PMID: 36841570 DOI: 10.1016/bs.pbr.2022.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
All modern mammals are descendants of the paraphyletic non-mammaliaform Synapsida, colloquially referred to as the "mammal-like reptiles." It has long been assumed that these mammalian ancestors were essentially reptile-like in their morphology, biology, and behavior, i.e., they had a small brain, displayed simple behavior, and their sensory organs were unrefined compared to those of modern mammals. Recent works have, however, revealed that neurological, sensory, and behavioral traits previously considered typically mammalian, such as whiskers, enhanced olfaction, nocturnality, parental care, and complex social interactions evolved before the origin of Mammaliaformes, among the early-diverging "mammal-like reptiles." In contrast, an enlarged brain did not evolve immediately after the origin of mammaliaforms. As such, in terms of paleoneurology, the last "mammal-like reptiles" were not significantly different from the earliest mammaliaforms. The abundant data and literature published in the last 10 years no longer supports the "three pulses" scenario of synapsid brain evolution proposed by Rowe and colleagues in 2011, but supports the new "outside-in" model of Rodrigues and colleagues proposed in 2018, instead. As Mesozoic reptiles were becoming the dominant taxa within terrestrial ecosystems, synapsids gradually adapted to smaller body sizes and nocturnality. This resulted in a sensory revolution in synapsids as olfaction, audition, and somatosensation compensated for the loss of visual cues. This altered sensory input is aligned with changes in the brain, the most significant of which was an increase in relative brain size.
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Abstract
Relationships between the complexity of the cranial sutures and the inferred ecology of dicynodont synapsids are explored. Simple complexity indices based on degree of sutural interdigitation were calculated for 70 anomodont species and indicate that the naso-frontal sutures of Cistecephalidae, a clade inferred to be dedicated fossors based on aspects of postcranial morphology, are substantially more complex than those of other dicynodonts. The elevated complexity of the naso-frontal suture in this clade is interpreted as being related to compressive forces sustained during burrowing, paralleling the condition in some other fossorial vertebrate groups (e.g., amphisbaenians). The most highly interdigitated sutures in the cistecephalid skull are those oriented transversely to its long axis, which would experience the greatest longitudinal stresses from contact with the substrate. Although it is uncertain to what degree cistecephalid burrowing was based on scratch vs. head-lift digging, it is argued that the head played an important role during locomotion in this group. Increased sutural complexity, rather than cranial fusion, as an adaptation to resisting compressive forces during burrowing may be related to indeterminate growth in dicynodonts.
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8
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Kerber L, Ferreira JD, Fonseca PHM, Franco A, Martinelli AG, Soares MB, Ribeiro AM. An additional brain endocast of the ictidosaur Riograndia guaibensis (Eucynodontia: Probainognathia): intraspecific variation of endocranial traits. AN ACAD BRAS CIENC 2021; 93:e20200084. [PMID: 33681891 DOI: 10.1590/0001-3765202120200084] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 07/08/2020] [Indexed: 11/22/2022] Open
Abstract
Recently, the morphology and encephalization of the brain endocast of the Triassic non-mammaliaform probainognathian cynodont Riograndia guaibensis were studied. Here, we analyzed the brain endocast of an additional specimen of this species. The new endocast shows well-defined olfactory bulbs and a median sulcus dividing the hemispheres, traits that were not clearly observed in the first studied specimen. Encephalization quotients were also calculated, revealing similar values to other non-mammaliaform cynodonts and lower than those of the first analyzed specimen. The analyzed cranium is slightly larger than the first studied one and may represent an advanced ontogenetic stage. Hence, these differences may be related to the intraspecific variation of this cynodont or alternatively, to the preservation of each specimen.
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Affiliation(s)
- Leonardo Kerber
- Universidade Federal de Santa Maria, Centro de Apoio à Pesquisa Paleontológica, Rua Maximiliano Vizzotto, 598, 97230-000 São João do Polêsine, RS, Brazil.,Museu Paraense Emílio Goeldi, Coordenação de Ciências da Terra e Ecologia, Av. Perimetral, 1901, 66077-830 Belém, PA, Brazil.,Universidade Federal de Santa Maria, Programa de Pós-Graduação em Biodiversidade Animal, Av. Roraima 1000, 97105-900 Santa Maria, RS, Brazil
| | - JosÉ Darival Ferreira
- Universidade Federal de Santa Maria, Programa de Pós-Graduação em Biodiversidade Animal, Av. Roraima 1000, 97105-900 Santa Maria, RS, Brazil
| | - Pedro Henrique M Fonseca
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Geociências, Av. Bento Gonçalves, 9500, 91501-970 Porto Alegre, RS, Brazil
| | - Arymatheia Franco
- Universidade Federal de Santa Maria, Programa de Pós-Graduação em Biodiversidade Animal, Av. Roraima 1000, 97105-900 Santa Maria, RS, Brazil
| | - AgustÍn G Martinelli
- Museo Argentino de Ciencias Naturales 'Bernardino Rivadavia', CONICET-Sección Paleontología de Vertebrados, Av. Ángel Gallardo, 470, C1405 DJR, Buenos Aires, Argentina
| | - Marina Bento Soares
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Geociências, Av. Bento Gonçalves, 9500, 91501-970 Porto Alegre, RS, Brazil.,Universidade Federal do Rio de Janeiro, Museu Nacional, Departamento de Geologia e Paleontologia, Quinta da Boa Vista, São Cristóvão, 20940-040 Rio de Janeiro, RJ, Brazil
| | - Ana Maria Ribeiro
- Universidade Federal do Rio Grande do Sul, Programa de Pós-Graduação em Geociências, Av. Bento Gonçalves, 9500, 91501-970 Porto Alegre, RS, Brazil.,Secretaria do Meio Ambiente e Infraestrutura, Museu de Ciências Naturais, Seção de Paleontologia, Av. Salvador França, 1427, 90690-000 Porto Alegre, RS, Brazil
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9
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Franchini LF. Genetic Mechanisms Underlying Cortical Evolution in Mammals. Front Cell Dev Biol 2021; 9:591017. [PMID: 33659245 PMCID: PMC7917222 DOI: 10.3389/fcell.2021.591017] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 01/08/2021] [Indexed: 12/13/2022] Open
Abstract
The remarkable sensory, motor, and cognitive abilities of mammals mainly depend on the neocortex. Thus, the emergence of the six-layered neocortex in reptilian ancestors of mammals constitutes a fundamental evolutionary landmark. The mammalian cortex is a columnar epithelium of densely packed cells organized in layers where neurons are generated mainly in the subventricular zone in successive waves throughout development. Newborn cells move away from their site of neurogenesis through radial or tangential migration to reach their specific destination closer to the pial surface of the same or different cortical area. Interestingly, the genetic programs underlying neocortical development diversified in different mammalian lineages. In this work, I will review several recent studies that characterized how distinct transcriptional programs relate to the development and functional organization of the neocortex across diverse mammalian lineages. In some primates such as the anthropoids, the neocortex became extremely large, especially in humans where it comprises around 80% of the brain. It has been hypothesized that the massive expansion of the cortical surface and elaboration of its connections in the human lineage, has enabled our unique cognitive capacities including abstract thinking, long-term planning, verbal language and elaborated tool making capabilities. I will also analyze the lineage-specific genetic changes that could have led to the modification of key neurodevelopmental events, including regulation of cell number, neuronal migration, and differentiation into specific phenotypes, in order to shed light on the evolutionary mechanisms underlying the diversity of mammalian brains including the human brain.
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Affiliation(s)
- Lucía Florencia Franchini
- Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
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10
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de Simão-Oliveira D, Kerber L, L Pinheiro F. Endocranial morphology of the Brazilian Permian dicynodont Rastodon procurvidens (Therapsida: Anomodontia). J Anat 2019; 236:384-397. [PMID: 31670465 DOI: 10.1111/joa.13107] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2019] [Indexed: 12/18/2022] Open
Abstract
Dicynodontia is a major clade of terrestrial tetrapods that greatly diversified during the Permian and Triassic periods, reaching a worldwide distribution. In this study, the endocranial cavity of the Brazilian Permian dicynodont Rastodon procurvidens is described based on a digital endocast obtained using digital imaging (X-ray computed tomography) and 3D modeling. It was possible to reconstruct the brain, olfactory bulbs, inner ear, some neurovascular canals, cranial nerves, the nasal cavity, and the maxillary recesses. The endocast of R. procurvidens preserves a typical plesiomorphic morphology of non-mammaliaform therapsids, being predominantly tubular and displaying a relatively short and robust hindbrain. Encephalization quotients (EQs) were calculated for R. procurvidens, resulting in EQs of 0.09 ± 0.03 and 0.13 ± 0.05 (Jerison's EQ and Manger's EQ, respectively). Finally, some biological implications of the endocast morphology were inferred for R. procurvidens. Its inner ear is especially small, and its orientation implies a slightly downturned head posture in life. Furthermore, the presence of uncompressed maxillary recesses in R. procurvidens indicates a correlation between the enlargement of the recesses and the reduction of the tusks, also seen in other dicynodonts with reduced tusks.
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Affiliation(s)
- Daniel de Simão-Oliveira
- Laboratório de Paleobiologia, Programa de Pós-Graduação em Ciências Biológicas, Universidade Federal do Pampa (Unipampa), São Gabriel, Rio Grande do Sul, Brazil.,Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia (CAPPA), Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria (UFSM), São João do Polêsine, Rio Grande do Sul, Brazil
| | - Leonardo Kerber
- Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia (CAPPA), Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria (UFSM), São João do Polêsine, Rio Grande do Sul, Brazil
| | - Felipe L Pinheiro
- Laboratório de Paleobiologia, Programa de Pós-Graduação em Ciências Biológicas, Universidade Federal do Pampa (Unipampa), São Gabriel, Rio Grande do Sul, Brazil
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Pavanatto AEB, Kerber L, Dias-da-Silva S. Virtual reconstruction of cranial endocasts of traversodontid cynodonts (Eucynodontia: Gomphodontia) from the upper Triassic of Southern Brazil. J Morphol 2019; 280:1267-1281. [PMID: 31241801 DOI: 10.1002/jmor.21029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 06/03/2019] [Accepted: 06/10/2019] [Indexed: 12/12/2022]
Abstract
The brain endocasts of the late Triassic (Carnian) traversodontids (Eucynodontia: Gomphodontia) Siriusgnathus niemeyerorum and Exaeretodon riograndensis from southern Brazil are described based on virtual models generated using computed tomography scan data. Their skull anatomy resembles that of other non-mammaliaform cynodonts, showing an endocranial cavity that is not fully ossified. A "V-shaped" orbitosphenoid, neither fully developed nor ossified is present in E. riograndensis. The nasal cavity is confluent with the encephalic cavity. Thus, the anterior limit of the olfactory bulbs is not definite. The brain endocast is elongated, being narrow anteriorly and wide posteriorly, with the maximum width at the parafloccular cast. The olfactory bulbs do not present a clear division between their counterparts, due to the absence of a longitudinal sulcus. A longitudinal sulcus in the forebrain delimiting the cerebral hemispheres, the pineal tube, and the parietal foramen are absent in both taxa. The large and well-developed unossified zone is partially separated from the remaining endocast by a notch formed by the supraoccipital. The encephalization quotients, as well as the endocranial volume/body mass relationships of S. niemeyerorum and E. riograndensis are within the range expected for non-mammaliaform Therapsida.
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Affiliation(s)
- Ane E B Pavanatto
- Programa de Pós-Graduação em Biodiversidade Animal, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, 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
| | - Sérgio Dias-da-Silva
- 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
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12
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Benoit J, Ruf I, Miyamae JA, Fernandez V, Rodrigues PG, Rubidge BS. The Evolution of the Maxillary Canal in Probainognathia (Cynodontia, Synapsida): Reassessment of the Homology of the Infraorbital Foramen in Mammalian Ancestors. J MAMM EVOL 2019. [DOI: 10.1007/s10914-019-09467-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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13
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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: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [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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14
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Urciuoli A, Zanolli C, Fortuny J, Almécija S, Schillinger B, Moyà‐Solà S, Alba DM. Neutron‐based computed microtomography:
Pliobates cataloniae
and
Barberapithecus huerzeleri
as a test‐case study. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2018; 166:987-993. [DOI: 10.1002/ajpa.23467] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 02/21/2018] [Accepted: 03/06/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Alessandro Urciuoli
- Institut Català de Paleontologia Miquel CrusafontUniversitat Autònoma de Barcelona, Edifici ICTA‐ICPc/Columnes s/n, Campus de la UAB, 08193 Cerdanyola del Vallès, Barcelona Spain
| | - Clément Zanolli
- Laboratoire AMIS, UMR 5288 CNRSUniversité Toulouse III Paul SabatierToulouse France
| | - Josep Fortuny
- Institut Català de Paleontologia Miquel CrusafontUniversitat Autònoma de Barcelona, Edifici ICTA‐ICPc/Columnes s/n, Campus de la UAB, 08193 Cerdanyola del Vallès, Barcelona Spain
- Centre de Recherches en Paléobiodiversité et PaléoenvironnementsMuséum National d'Histoire Naturelle, Bâtiment de PaléontologieCP38, 8 rue Buffon, Paris 75005 France
| | - Sergio Almécija
- Institut Català de Paleontologia Miquel CrusafontUniversitat Autònoma de Barcelona, Edifici ICTA‐ICPc/Columnes s/n, Campus de la UAB, 08193 Cerdanyola del Vallès, Barcelona Spain
- Center for the Advanced Study of Human Paleobiology, Department of AnthropologyThe George Washington UniversityWashington DC 20052
| | - Burkhard Schillinger
- Technische Universität MünchenFakultat für Physik E21, James‐Franck‐Str.1, Garching D‐85747 Germany
| | - Salvador Moyà‐Solà
- Institut Català de Paleontologia Miquel CrusafontUniversitat Autònoma de Barcelona, Edifici ICTA‐ICPc/Columnes s/n, Campus de la UAB, 08193 Cerdanyola del Vallès, Barcelona Spain
- Institució Catalana de Recerca i Estudis AvançatsPg. Lluís Companys 23, Barcelona 08010 Spain
- Unitat d'Antropologia, Departament de Biologia Animal, Biologia Vegetal i EcologiaUniversitat Autònoma de BarcelonaCerdanyola del Vallès, Barcelona 08193 Spain
| | - David M. Alba
- Institut Català de Paleontologia Miquel CrusafontUniversitat Autònoma de Barcelona, Edifici ICTA‐ICPc/Columnes s/n, Campus de la UAB, 08193 Cerdanyola del Vallès, Barcelona Spain
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Benoit J, Angielczyk KD, Miyamae JA, Manger P, Fernandez V, Rubidge B. Evolution of facial innervation in anomodont therapsids (Synapsida): Insights from X-ray computerized microtomography. J Morphol 2018; 279:673-701. [PMID: 29464761 DOI: 10.1002/jmor.20804] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 01/29/2018] [Accepted: 02/03/2018] [Indexed: 12/11/2022]
Abstract
Anomodontia was the most successful herbivorous clade of the mammalian stem lineage (non-mammalian synapsids) during the late Permian and Early Triassic. Among anomodonts, Dicynodontia stands apart because of the presence of an osseous beak that shows evidence of the insertion of a cornified sheath, the ramphotheca. In this study, fourteen anomodont specimens were microCT-scanned and their trigeminal canals reconstructed digitally to understand the origin and evolution of trigeminal nerve innervation of the ramphotheca. We show that the pattern of innervation of the anomodont "beak" is more similar to that in chelonians (the nasopalatine branch is enlarged and innervates the premaxillary part of the ramphotheca) than in birds (where the nasopalatine and maxillary branches play minor roles). The nasopalatine branch is noticeably enlarged in the beak-less basal anomodont Patranomodon, suggesting that this could be an anomodont or chainosaur synapomorphy. Our analyses suggest that the presence or absence of tusks and postcanine teeth are often accompanied by corresponding variations of the rami innervating the caniniform process and the alveolar region, respectively. The degree of ossification of the canal for the nasal ramus of the ophthalmic branch also appears to correlate with the presence of a nasal boss. The nasopalatine canal is absent from the premaxilla in the Bidentalia as they uniquely show a large plexus formed by the internal nasal branch of the maxillary canal instead. The elongated shape of this plexus in Lystrosaurus supports the hypothesis that the rostrum evolved as an elongation of the subnarial region of the snout. Finally, the atrophied and variable aspect of the trigeminal canals in Myosaurus supports the hypothesis that this genus had a reduced upper ramphotheca.
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Affiliation(s)
- Julien Benoit
- Evolutionary Studies Institute (ESI), School of Geosciences, University of the Witwatersrand, Johannesburg, 2050, South Africa
| | - Kenneth D Angielczyk
- Evolutionary Studies Institute (ESI), School of Geosciences, University of the Witwatersrand, Johannesburg, 2050, South Africa.,Integrative Research Center, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, Illinois, 60605
| | - Juri A Miyamae
- Department of Geology & Geophysics, P.O. Box 208109, Yale University, New Haven, Connecticut, 06520-8109
| | - Paul Manger
- School of Anatomical Sciences, University of the Witwatersrand, Johannesburg, 2193, South Africa
| | - Vincent Fernandez
- European Synchrotron Radiation Facility, Beamline ID19, Grenoble, 38000, France
| | - Bruce Rubidge
- Evolutionary Studies Institute (ESI), School of Geosciences, University of the Witwatersrand, Johannesburg, 2050, South Africa
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