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Martinelli AG, Ezcurra MD, Fiorelli LE, Escobar J, Hechenleitner EM, von Baczko MB, Taborda JRA, Desojo JB. A new early-diverging probainognathian cynodont and a revision of the occurrence of cf. Aleodon from the Chañares Formation, northwestern Argentina: New clues on the faunistic composition of the latest Middle-?earliest Late Triassic Tarjadia Assemblage Zone. Anat Rec (Hoboken) 2024; 307:818-850. [PMID: 38282519 DOI: 10.1002/ar.25388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 01/03/2024] [Accepted: 01/08/2024] [Indexed: 01/30/2024]
Abstract
The Chañares Formation (Ischigualasto-Villa Unión Basin) is worldwide known by its exquisitely preserved fossil record of latest Middle-to-early Late Triassic tetrapods, including erpetosuchids, "rauisuchians," proterochampsids, gracilisuchids, dinosauromorphs, pterosauromorphs, kannemeyeriiform dicynodonts, and traversodontid, chiniquodontid and probainognathid cynodonts, coming from the Tarjadia (bottom) and Massetognathus-Chanaresuchus (top) Assemblage Zones of its lower member. Regarding cynodonts, most of its profuse knowledge comes from the traditional layers discovered by Alfred Romer and his team in the 1960s that are now enclosed in the Massetognathus-Chanaresuchus Assemblage Zone (AZ). In this contribution we focus our study on the probainognathian cynodonts discovered in levels of the Tarjadia Assemblage Zone. We describe a new chiniquodontid cynodont with transversely broad postcanine teeth (Riojanodon nenoi gen. et sp. nov.) which is related to the genus Aleodon. In addition, the specimen CRILAR-Pv 567 previously referred to cf. Aleodon is here described, compared, and included in a phylogenetic analysis. It is considered as an indeterminate Aleodontinae nov., a clade here proposed to included chiniquodontids with transversely broad upper and lower postcanines, by having a cuspidated sectorial labial margin and a lingual platform that is twice broader than a lingual cingulum. Cromptodon mamiferoides, from the Cerro de Las Cabras Formation (Cuyo Basin), was also included in the phylogenetic analysis and recovered as an Aleodontinae. The new cynodont and the record of Aleodontinae indet. reinforce the faunal differentiation between the Tarjadia and Massetognathus-Chanaresuchus Assemblage Zones, in the lower member of the Chañares Formation, and inform on the diverse chiniquodontid clade with both sectorial and transversely broad postcanine teeth.
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Affiliation(s)
- Agustín G Martinelli
- Sección Paleontología de Vertebrados, CONICET-Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Martín D Ezcurra
- Sección Paleontología de Vertebrados, CONICET-Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Lucas E Fiorelli
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (Prov. de La Rioja-UNLaR-SEGEMAR-UNCa-CONICET), La Rioja, Argentina
| | - Juan Escobar
- Sección Paleontología de Vertebrados, CONICET-Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - E Martín Hechenleitner
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja (Prov. de La Rioja-UNLaR-SEGEMAR-UNCa-CONICET), La Rioja, Argentina
| | - M Belén von Baczko
- Sección Paleontología de Vertebrados, CONICET-Museo Argentino de Ciencias Naturales "Bernardino Rivadavia", Buenos Aires, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Jeremías R A Taborda
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- CICTERRA, Ciudad Universitaria, Córdoba, Argentina
| | - Julia B Desojo
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- División Paleontología Vertebrados, Museo de La Plata, Facultad de Ciencias Naturales y Museo, Buenos Aires, Argentina
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Norton LA, Abdala F, Benoit J. Craniodental anatomy in Permian-Jurassic Cynodontia and Mammaliaformes (Synapsida, Therapsida) as a gateway to defining mammalian soft tissue and behavioural traits. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220084. [PMID: 37183903 PMCID: PMC10184251 DOI: 10.1098/rstb.2022.0084] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023] Open
Abstract
Mammals are diagnosed by more than 30 osteological characters (e.g. squamosal-dentary jaw joint, three inner ear ossicles, etc.) that are readily preserved in the fossil record. However, it is the suite of physiological, soft tissue and behavioural characters (e.g. endothermy, hair, lactation, isocortex and parental care), the evolutionary origins of which have eluded scholars for decades, that most prominently distinguishes living mammals from other amniotes. Here, we review recent works that illustrate how evolutionary changes concentrated in the cranial and dental morphology of mammalian ancestors, the Permian-Jurassic Cynodontia and Mammaliaformes, can potentially be used to document the origin of some of the most crucial defining features of mammals. We discuss how these soft tissue and behavioural traits are highly integrated, and how their evolution is intermingled with that of craniodental traits, thus enabling the tracing of their previously out-of-reach phylogenetic history. Most of these osteological and dental proxies, such as the maxillary canal, bony labyrinth and dental replacement only recently became more easily accessible-thanks, in large part, to the widespread use of X-ray microtomography scanning in palaeontology-because they are linked to internal cranial characters. This article is part of the theme issue 'The mammalian skull: development, structure and function'.
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Affiliation(s)
- Luke A Norton
- Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Wits 2050, Johannesburg, South Africa
| | - Fernando Abdala
- Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Wits 2050, Johannesburg, South Africa
- Unidad Ejecutora Lillo, CONICET-Fundación Miguel Lillo, Miguel Lillo 251, Tucumán 4000, Argentina
| | - Julien Benoit
- Evolutionary Studies Institute, University of the Witwatersrand, Private Bag 3, Wits 2050, Johannesburg, South Africa
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3
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Abdala F, Norton LA, Jasinoski SC, Botha J, Fernandez V, Rubidge B, Gill PG, Martinelli AG. On taxonomic issues, ontogenetic series and tooth replacement. Comments on Diphyodont tooth replacement of Brasilodon-A late Triassic eucynodont that challenges the time of origin of mammals by Cabreira et al. J Anat 2023; 242:737-742. [PMID: 36715111 PMCID: PMC10008281 DOI: 10.1111/joa.13803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 11/23/2022] [Indexed: 01/31/2023] Open
Affiliation(s)
- Fernando Abdala
- Unidad Ejecutora Lillo (CONICET-Fundación Miguel Lillo), Tucumán, Argentina.,Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Luke A Norton
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Sandra C Jasinoski
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Jennifer Botha
- National Museum, Bloemfontein, South Africa.,Department of Zoology and Entomology, University of the Free State, Bloemfontein, South Africa
| | - Vincent Fernandez
- European Synchrotron Radiation Facility, Structure of Materials Department, Grenoble, France
| | - Bruce Rubidge
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Pamela G Gill
- School of Earth Sciences, University of Bristol, Bristol, UK.,Department of Earth Sciences, Natural History Museum London, London, UK
| | - Agustín G Martinelli
- Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"-Consejo Nacional de Investigaciones Científicas y Técnicas (MACN-CONICET), Ciudad Autónoma de Buenos Aires, Argentina
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A complete skull of a stem mammal from the Late Triassic of Brazil illuminates the early evolution of prozostrodontian cynodonts. J MAMM EVOL 2023. [DOI: 10.1007/s10914-022-09648-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Cabreira SF, Schultz CL, da Silva LR, Lora LHP, Pakulski C, do Rêgo RCB, Soares MB, Smith MM, Richter M. Diphyodont tooth replacement of Brasilodon-A Late Triassic eucynodont that challenges the time of origin of mammals. J Anat 2022; 241:1424-1440. [PMID: 36065514 PMCID: PMC9644961 DOI: 10.1111/joa.13756] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 08/09/2022] [Accepted: 08/16/2022] [Indexed: 11/28/2022] Open
Abstract
Two sets of teeth (diphyodonty) characterise extant mammals but not reptiles, as they generate many replacement sets (polyphyodonty). The transition in long-extinct species from many sets to only two has to date only been reported in Jurassic eucynodonts. Specimens of the Late Triassic brasilodontid eucynodont Brasilodon have provided anatomical and histological data from three lower jaws of different growth stages. These reveal ordered and timed replacement of deciduous by adult teeth. Therefore, this diphyodont dentition, as contemporary of the oldest known dinosaurs, shows that Brasilodon falls within a range of wide variations of typically mammalian, diphyodont dental patterns. Importantly, these three lower jaws represent distinct ontogenetic stages that reveal classic features for timed control of replacement, by the generation of only one replacement set of teeth. This data shows that the primary premolars reveal a temporal replacement pattern, importantly from directly below each tooth, by controlled regulation of tooth resorption and regeneration. The complexity of the adult prismatic enamel structure with a conspicuous intra-structural Schmelzmuster array suggests that, as in the case of extant mammals, this extinct species would have probably sustained higher metabolic rates than reptiles. Furthermore, in modern mammals, diphyodonty and prismatic enamel are inextricably linked, anatomically and physiologically, to a set of other traits including placentation, endothermy, fur, lactation and even parental care. Our analysis of the osteodental anatomy of Brasilodon pushes back the origin of diphyodonty and consequently, its related biological traits to the Norian (225.42 ± 0.37 myr), and around 25 myr after the End-Permian mass extinction event.
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Affiliation(s)
- Sergio F Cabreira
- Associação Sul Brasileira de Paleontologia, Faxinal do Soturno, Brazil
| | - Cesar L Schultz
- Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Lúcio R da Silva
- Associação Sul Brasileira de Paleontologia, Faxinal do Soturno, Brazil
| | | | | | | | - Marina B Soares
- Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.,Departamento de Geologia e Paleontologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Moya Meredith Smith
- Earth Sciences Department, Natural History Museum, London, UK.,Centre for Craniofacial and Regenerative Biology, King's College London, London, UK
| | - Martha Richter
- Earth Sciences Department, Natural History Museum, London, UK
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6
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Duhamel A, Benoit J, Day M, Rubidge B, Fernandez V. Computed Tomography elucidates ontogeny within the basal therapsid clade Biarmosuchia. PeerJ 2021; 9:e11866. [PMID: 34527434 PMCID: PMC8403480 DOI: 10.7717/peerj.11866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 07/05/2021] [Indexed: 11/20/2022] Open
Abstract
Biarmosuchia is a clade of basal therapsids that includes forms possessing plesiomorphic ‘pelycosaurian’ cranial characters as well as the highly derived Burnetiamorpha which are characterised by cranial pachyostosis and a variety of cranial bosses. Potential ontogenetic variation in these structures has been suggested based on growth series of other therapsids with pachyostosed crania, which complicates burnetiamorph taxonomic distinction and thus it is essential to better understand cranial ontogeny of the Burnetiamorpha. Here, three new juvenile biarmosuchian skulls from the late Permian of South Africa are described using X-ray micro computed tomography (CT). We found that juvenile biarmosuchians are distinguished from adults by their relatively large orbits, open cranial sutures, and incomplete ossification of the braincase and bony labyrinth. Also, they manifest multiple centres of ossification within the parietal and preparietal bones. CT examination reveals that the holotype of Lemurosaurus pricei (BP/1/816), previously alleged to be a juvenile, shows no evidence of juvenility and is thus probably an adult. This suggests that the larger skull NMQR 1702, previously considered to be an adult L. pricei, may represent a new taxon. This study provides, for the first time, a list of characters by which to recognise juvenile biarmosuchians.
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Affiliation(s)
- Aliénor Duhamel
- ENS de Lyon, CNRS, UMR 5276, LGL-TPE, Université Claude Bernard (Lyon I), Lyon, France.,Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Julien Benoit
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Michael Day
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,Department of Earth Sciences, Natural History Museum, London, United Kingdom
| | - Bruce Rubidge
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa.,School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Vincent Fernandez
- Department of Earth Sciences, Natural History Museum, London, United Kingdom.,European Synchrotron Radiation Facility, Grenoble, France
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Olroyd SL, LeBlanc ARH, Araújo R, Angielczyk KD, Duhamel A, Benoit J, Amaral M. Histology and μCT reveal the unique evolution and development of multiple tooth rows in the synapsid Endothiodon. Sci Rep 2021; 11:16875. [PMID: 34413357 PMCID: PMC8377087 DOI: 10.1038/s41598-021-95993-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 07/27/2021] [Indexed: 02/07/2023] Open
Abstract
Several amniote lineages independently evolved multiple rows of marginal teeth in response to the challenge of processing high fiber plant matter. Multiple tooth rows develop via alterations to tooth replacement in captorhinid reptiles and ornithischian dinosaurs, but the specific changes that produce this morphology differ, reflecting differences in their modes of tooth attachment. To further understand the mechanisms by which multiple tooth rows can develop, we examined this feature in Endothiodon bathystoma, a member of the only synapsid clade (Anomodontia) to evolve a multi-rowed marginal dentition. We histologically sampled Endothiodon mandibles with and without multiple tooth rows as well as single-rowed maxillae. We also segmented functional and replacement teeth in µ-CT scanned mandibles and maxillae of Endothiodon and several other anomodonts with 'postcanine' teeth to characterize tooth replacement in the clade. All anomodonts in our sample displayed a space around the tooth roots for a soft tissue attachment between tooth and jaw in life. Trails of alveolar bone indicate varying degrees of labial migration of teeth through ontogeny, often altering the spatial relationships of functional and replacement teeth in the upper and lower jaws. We present a model of multiple tooth row development in E. bathystoma in which labial migration of functional teeth was extensive enough to prevent resorption and replacement by newer generations of teeth. This model represents another mechanism by which multiple tooth rows evolved in amniotes. The multiple tooth rows of E. bathystoma may have provided more extensive contact between the teeth and a triturating surface on the palatine during chewing.
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Affiliation(s)
| | - Aaron R H LeBlanc
- Centre for Oral, Clinical & Translational Sciences, King's College London, London, UK
| | - Ricardo Araújo
- Instituto de Plasmas e Fusão Nuclear, Universidade de Lisboa, Lisbon, Portugal
| | - Kenneth D Angielczyk
- Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, USA
| | - Aliénor Duhamel
- Evolutionary Studies Institute, School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Julien Benoit
- Evolutionary Studies Institute, School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
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