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Pusch LC, Kammerer CF, Fröbisch J. The origin and evolution of Cynodontia (Synapsida, Therapsida): Reassessment of the phylogeny and systematics of the earliest members of this clade using 3D-imaging technologies. Anat Rec (Hoboken) 2024; 307:1634-1730. [PMID: 38444024 DOI: 10.1002/ar.25394] [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: 10/12/2023] [Revised: 01/13/2024] [Accepted: 01/14/2024] [Indexed: 03/07/2024]
Abstract
The origin of cynodonts, the group ancestral to and including mammals, is one of the major outstanding problems in therapsid evolution. One of the most troubling aspects of the cynodont fossil record is the lengthy Permian ghost lineage between the latest possible divergence from its sister group Therocephalia and the first appearance of definitive cynodonts in the late Permian. The absence of cynodonts and dominance of therocephalians in middle Permian strata has led some workers to argue that cynodonts evolved from within therocephalians, rendering the latter paraphyletic, but more recent analyses support the reciprocal monophyly of Cynodontia and Therocephalia. Furthermore, although a fundamental dichotomy in the derived subclade Eucynodontia is well-supported in cynodont phylogeny, the relationships of more stemward cynodonts from the late Permian and Early Triassic are unresolved. Here, we provide a re-evaluation of the phylogeny of Eutheriodontia (Cynodontia + Therocephalia) and an assessment of character evolution within the group. Using computed tomographic data derived from extensive sampling of the earliest known (late Permian and Early Triassic) cynodonts and selected exemplars of therocephalians and later (Middle Triassic onwards) cynodonts, we describe novel aspects of the endocranial anatomy of these animals. These data were incorporated into a new phylogenetic data set including a comprehensive sample of early cynodonts. Our phylogenetic analyses support some results previously recovered by other authors, but recover therocephalians as paraphyletic with regards to cynodonts, with cynodonts and eutherocephalians forming a clade to the exclusion of the "basal therocephalian" families Lycosuchidae and Scylacosauridae. Though both conservatism and homoplasy mark the endocranial anatomy of early non-mammalian cynodonts, we were able to identify several new endocranial synapomorphies for eutheriodont subclades and recovered generally better-supported topologies than previous analyses using primarily external craniodental characters.
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Affiliation(s)
- Luisa C Pusch
- Museum für Naturkunde, Leibniz-Institut füsr Evolutions- und Biodiversitätsforschung, Berlin, Germany
- Institut für Biologie, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Christian F Kammerer
- North Carolina Museum of Natural Sciences, Raleigh, North Carolina, USA
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Jörg Fröbisch
- Museum für Naturkunde, Leibniz-Institut füsr 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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2
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Kerber L, Roese-Miron L, Medina TGM, da Roberto-da-Silva L, Cabreira SF, Pretto FA. Skull anatomy and paleoneurology of a new traversodontid from the Middle-Late Triassic of Brazil. Anat Rec (Hoboken) 2024; 307:791-817. [PMID: 38282563 DOI: 10.1002/ar.25385] [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: 10/16/2023] [Revised: 12/28/2023] [Accepted: 12/30/2023] [Indexed: 01/30/2024]
Abstract
Traversodontidae, a clade of gomphodont cynodonts, thrived during the Middle and Late Triassic, displaying a wide geographical distribution. During fieldwork in 2009, a new specimen was discovered in Ladinian/early Carnian stratigraphic layers in southern Brazil. Here, we describe this specimen and propose a new taxon closely related to Traversodon stahleckeri (Traversodontinae) but displaying a unique combination of traits (e.g., presence of a poorly developed suborbital process, mesiodistal length of the paracanine fossa similar to the length of the canine, short diastema between the fourth incisor and the upper canine, and coronoid process not entirely covering the distalmost lower postcanine). Furthermore, the endocranial anatomy of the new taxon was examined. The reconstruction of the cranial endocast revealed paleoneurological features consistent with non-Gomphodontosuchinae traversodontids. These features include the presence of a pineal body (but the absence of an open parietal foramen). These recent findings contribute significantly to our understanding of the evolutionary history and cranial anatomy of Middle-Late Triassic traversodontids, shedding light on the diversity and adaptations of non-mammaliaform cynodonts.
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Affiliation(s)
- Leonardo Kerber
- Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria (CAPPA/UFSM), São João do Polêsine, Brazil
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Lívia Roese-Miron
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Thais G M Medina
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | | | | | - Flávio A Pretto
- Centro de Apoio à Pesquisa Paleontológica da Quarta Colônia, Universidade Federal de Santa Maria (CAPPA/UFSM), São João do Polêsine, Brazil
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
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3
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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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Beck RM, Voss RS, Jansa SA. Craniodental Morphology and Phylogeny of Marsupials. BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY 2022. [DOI: 10.1206/0003-0090.457.1.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Robin M.D. Beck
- School of Science, Engineering and Environment University of Salford, U.K. School of Biological, Earth & Environmental Sciences University of New South Wales, Australia Division of Vertebrate Zoology (Mammalogy) American Museum of Natural History
| | - Robert S. Voss
- Division of Vertebrate Zoology (Mammalogy) American Museum of Natural History
| | - Sharon A. Jansa
- Bell Museum and Department of Ecology, Evolution, and Behavior University of Minnesota
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Krause DW, Hoffmann S, Lyson TR, Dougan LG, Petermann H, Tecza A, Chester SGB, Miller IM. New Skull Material of Taeniolabis taoensis (Multituberculata, Taeniolabididae) from the Early Paleocene (Danian) of the Denver Basin, Colorado. J MAMM EVOL 2021; 28:1083-1143. [PMID: 34924738 PMCID: PMC8667543 DOI: 10.1007/s10914-021-09584-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/27/2021] [Indexed: 11/26/2022]
Abstract
Taeniolabis taoensis is an iconic multituberculate mammal of early Paleocene (Puercan 3) age from the Western Interior of North America. Here we report the discovery of significant new skull material (one nearly complete cranium, two partial crania, one nearly complete dentary) of T. taoensis in phosphatic concretions from the Corral Bluffs study area, Denver Formation (Danian portion), Denver Basin, Colorado. The new skull material provides the first record of the species from the Denver Basin, where the lowest in situ specimen occurs in river channel deposits ~730,000 years after the Cretaceous-Paleogene boundary, roughly coincident with the first appearance of legumes in the basin. The new material, in combination with several previously described and undescribed specimens from the Nacimiento Formation of the San Juan Basin, New Mexico, is the subject of detailed anatomical study, aided by micro-computed tomography. Our analyses reveal many previously unknown aspects of skull anatomy. Several regions (e.g., anterior portions of premaxilla, orbit, cranial roof, occiput) preserved in the Corral Bluffs specimens allow considerable revision of previous reconstructions of the external cranial morphology of T. taoensis. Similarly, anatomical details of the ascending process of the dentary are altered in light of the new material. Although details of internal cranial anatomy (e.g., nasal and endocranial cavities) are difficult to discern in the available specimens, we provide, based on UCMP 98083 and DMNH.EPV 95284, the best evidence to date for inner ear structure in a taeniolabidoid multituberculate. The cochlear canal of T. taoensis is elongate and gently curved and the vestibule is enlarged, although to a lesser degree than in Lambdopsalis.
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Affiliation(s)
- David W. Krause
- Department of Earth Sciences, Denver Museum of Nature & Science, 2001 Colorado Boulevard, Denver, CO 80205 USA
- Department of Anatomical Sciences, Stony Brook University, Stony Brook, NY 11794-8081 USA
| | - Simone Hoffmann
- Department of Anatomy, College of Osteopathic Medicine, New York Institute of Technology, Old Westbury, NY 11568 USA
| | - Tyler R. Lyson
- Department of Earth Sciences, Denver Museum of Nature & Science, 2001 Colorado Boulevard, Denver, CO 80205 USA
| | - Lindsay G. Dougan
- Department of Earth Sciences, Denver Museum of Nature & Science, 2001 Colorado Boulevard, Denver, CO 80205 USA
| | - Holger Petermann
- Department of Earth Sciences, Denver Museum of Nature & Science, 2001 Colorado Boulevard, Denver, CO 80205 USA
| | - Adrienne Tecza
- Department of Earth Sciences, Denver Museum of Nature & Science, 2001 Colorado Boulevard, Denver, CO 80205 USA
| | - Stephen G. B. Chester
- Department of Anthropology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210 USA
- Department of Anthropology, The Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016 USA
- New York Consortium in Evolutionary Primatology, 200 Central Park West, New York, NY 10024 USA
| | - Ian M. Miller
- Department of Earth Sciences, Denver Museum of Nature & Science, 2001 Colorado Boulevard, Denver, CO 80205 USA
- National Geographic Society, 1145 17th Street NW, Washington, DC 20036 USA
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Mammalian Petrosals from the Upper Jurassic Morrison Formation (Utah, USA) Reveal Non-canonical Evolution of Middle and Inner Ear Characters. J MAMM EVOL 2021. [DOI: 10.1007/s10914-021-09586-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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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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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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Benoit J, Jasinoski SC, Fernandez V, Abdala F. The mystery of a missing bone: revealing the orbitosphenoid in basal Epicynodontia (Cynodontia, Therapsida) through computed tomography. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2017; 104:66. [PMID: 28721557 DOI: 10.1007/s00114-017-1487-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 04/12/2017] [Accepted: 06/29/2017] [Indexed: 11/26/2022]
Abstract
The basal non-mammaliaform cynodonts from the late Permian (Lopingian) and Early Triassic are a major source of information for the understanding of the evolutionary origin of mammals. Detailed knowledge of their anatomy is critical for understanding the phylogenetic transition toward mammalness and the paleobiological reconstruction of mammalian precursors. Using micro-computed tomography (μCT), we describe the internal morphology of the interorbital region that includes the rarely fossilized orbitosphenoid elements in four basal cynodonts. These paired bones, which are positioned relatively dorsally in the skull, contribute to the wall of the anterior part of the braincase and form the floor for the olfactory lobes. Unlike procynosuchids and the more basal therapsids in which the orbitosphenoids are well developed, dense, and bear a ventral keel, the basal epicynodonts Cynosaurus, Galesaurus, and Thrinaxodon display cancellous, reduced, and loosely articulated orbitosphenoids, a condition shared with many eucynodonts. The hemi-cylindrical orbitosphenoid from which the mammalian condition is derived re-evolved convergently in traversodontid and some probainognathian cynodonts.
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Affiliation(s)
- Julien Benoit
- Evolutionary Studies Institute; School of Geosciences, University of the Witwatersrand, Private Bag 3, WITS, Johannesburg, 2050, South Africa.
- School of Anatomical Sciences, University of the Witwatersrand, 7 York Road, Johannesburg, 2193, South Africa.
| | - Sandra C Jasinoski
- Evolutionary Studies Institute; School of Geosciences, University of the Witwatersrand, Private Bag 3, WITS, Johannesburg, 2050, South Africa
| | - Vincent Fernandez
- European Synchrotron Radiation Facility, 71 rue des Martyrs, 38000, Grenoble, France
| | - Fernando Abdala
- Evolutionary Studies Institute; School of Geosciences, University of the Witwatersrand, Private Bag 3, WITS, Johannesburg, 2050, South Africa
- Unidad Ejecutora Lillo CONICET, Miguel Lillo, 251, Tucumán, Argentina
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