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Pinto JL, Marshall CR, Nesbitt SJ, Varajão de Latorre D. Quantitative evidence for dimorphism suggests sexual selection in the maxillary caniniform process of Placerias hesternus. PLoS One 2024; 19:e0297894. [PMID: 38820280 PMCID: PMC11142433 DOI: 10.1371/journal.pone.0297894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 01/16/2024] [Indexed: 06/02/2024] Open
Abstract
Placerias hesternus, a Late Triassic dicynodont, is one of the last megafaunal synapsids of the Mesozoic. The species has a tusk-like projection on its maxillary bone, known as the caniniform process. This process has been hypothesized to be sexually dimorphic since the 1950s, however this claim has not been thoroughly investigated quantitatively. Here, we examined maxillae, premaxillae, quadrates, and fibulae from a single population from the Placerias Quarry in the Blue Mesa Member of the Chinle Formation, near St. Johns, Arizona, USA to determine if the caniniform process is dimorphic. We made a total of 25 measurements from the four bones and used a maximum likelihood framework to compare the fit of unimodal versus bimodal distributions for each set of measurements. Our results from complete maxillae reveal that the caniniform process has two distinct morphs, with a shorter and longer form. This interpretation is substantiated both by strong statistical support for bimodal distribution of caniniform lengths, and by clustering analysis that clearly distinguishes two morphs for the maxillae. Clustering analysis also shows support for potential dimorphism in the shape of the quadrate. However, no measurements from elements other than the maxilla have a strong likelihood of bimodal distribution. These results support the long-standing hypothesis that the caniniform in Placerias was dimorphic. Alternative explanations to sexual dimorphism that could account for the dimorphism among these fossils include the presence of juveniles in the sample or time-averaged sampling of a chronospecies, but both have been previously rejected for the Placerias Quarry population. The lack of strong dimorphism in non-maxilla elements and increased variation in caniniform length of the large-caniniform morph suggest that the caniniform is a secondary sexual trait, possibly used in intraspecific competition.
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Affiliation(s)
- James L. Pinto
- Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, California, United States of America
| | - Charles R. Marshall
- Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, California, United States of America
| | - Sterling J. Nesbitt
- Department of Geosciences, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Daniel Varajão de Latorre
- Department of Integrative Biology and Museum of Paleontology, University of California, Berkeley, California, United States of America
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2
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Bishop PJ, Pierce SE. The fossil record of appendicular muscle evolution in Synapsida on the line to mammals: Part II-Hindlimb. Anat Rec (Hoboken) 2024; 307:1826-1896. [PMID: 37727023 DOI: 10.1002/ar.25310] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 07/15/2023] [Accepted: 08/08/2023] [Indexed: 09/21/2023]
Abstract
This paper is the second in a two-part series that charts the evolution of appendicular musculature along the mammalian stem lineage, drawing upon the exceptional fossil record of extinct synapsids. Here, attention is focused on muscles of the hindlimb. Although the hindlimb skeleton did not undergo as marked a transformation on the line to mammals as did the forelimb skeleton, the anatomy of extant tetrapods indicates that major changes to musculature have nonetheless occurred. To better understand these changes, this study surveyed the osteological evidence for muscular attachments in extinct mammalian and nonmammalian synapsids, two extinct amniote outgroups, and a large selection of extant mammals, saurians, and salamanders. Observations were integrated into an explicit phylogenetic framework, comprising 80 character-state complexes covering all muscles crossing the hip, knee, and ankle joints. These were coded for 33 operational taxonomic units spanning >330 Ma of tetrapod evolution, and ancestral state reconstruction was used to evaluate the sequence of muscular evolution along the stem lineage from Amniota to Theria. The evolutionary history of mammalian hindlimb musculature was complex, nonlinear, and protracted, with several instances of convergence and pulses of anatomical transformation that continued well into the crown group. Numerous traits typically regarded as characteristically "mammalian" have much greater antiquity than previously recognized, and for some traits, most synapsids are probably more reflective of the ancestral amniote condition than are extant saurians. More broadly, this study highlights the utility of the fossil record in interpreting the evolutionary appearance of distinctive anatomies.
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Affiliation(s)
- Peter J Bishop
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
- Geosciences Program, Queensland Museum, Brisbane, Queensland, Australia
| | - Stephanie E Pierce
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
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3
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Bishop PJ, Pierce SE. The fossil record of appendicular muscle evolution in Synapsida on the line to mammals: Part I-Forelimb. Anat Rec (Hoboken) 2024; 307:1764-1825. [PMID: 37726984 DOI: 10.1002/ar.25312] [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: 03/17/2023] [Revised: 07/15/2023] [Accepted: 08/08/2023] [Indexed: 09/21/2023]
Abstract
This paper is the first in a two-part series that charts the evolution of appendicular musculature along the mammalian stem lineage, drawing upon the exceptional fossil record of extinct synapsids. Here, attention is focused on muscles of the forelimb. Understanding forelimb muscular anatomy in extinct synapsids, and how this changed on the line to mammals, can provide important perspective for interpreting skeletal and functional evolution in this lineage, and how the diversity of forelimb functions in extant mammals arose. This study surveyed the osteological evidence for muscular attachments in extinct mammalian and nonmammalian synapsids, two extinct amniote outgroups, and a large selection of extant mammals, saurians, and salamanders. Observations were integrated into an explicit phylogenetic framework, comprising 73 character-state complexes covering all muscles crossing the shoulder, elbow, and wrist joints. These were coded for 33 operational taxonomic units spanning >330 Ma of tetrapod evolution, and ancestral state reconstruction was used to evaluate the sequence of muscular evolution along the stem lineage from Amniota to Theria. In addition to producing a comprehensive documentation of osteological evidence for muscle attachments in extinct synapsids, this work has clarified homology hypotheses across disparate taxa and helped resolve competing hypotheses of muscular anatomy in extinct species. The evolutionary history of mammalian forelimb musculature was a complex and nonlinear narrative, punctuated by multiple instances of convergence and concentrated phases of anatomical transformation. More broadly, this study highlights the great insight that a fossil-based perspective can provide for understanding the assembly of novel body plans.
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Affiliation(s)
- Peter J Bishop
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
- Geosciences Program, Queensland Museum, Brisbane, Queensland, Australia
| | - Stephanie E Pierce
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
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4
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Shi YT, Liu J. The tetrapod fauna of the upper Permian Naobaogou Formation of China: 10. Jimusaria monanensis sp. nov. (Dicynodontia) shows a unique epipterygoid. PeerJ 2023; 11:e15783. [PMID: 37547715 PMCID: PMC10399559 DOI: 10.7717/peerj.15783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 07/03/2023] [Indexed: 08/08/2023] Open
Abstract
Jimusaria is the first reported Chinese dicynodont, previously only known from Xinjiang. Here we refer two specimens from the Naobaogou Formation, Nei Mongol, China to Jimusaria based on the following features: squamosal separated from supraoccipital by tabular, tabular contacting opisthotic, sharp and thin lateral dentary shelf expanding anteriorly into a thick swelling, nasals fused as single element, rod-like medial bar formed by footplate of epipterygoid connecting to the parabasisphenoid and periotic medially. A new species, J. monanensis, is named based on the diagnostic characters on these two specimens such as distinct caniniform buttress lacking posteroventral furrow, naso-frontal suture forming an anterior directed sharp angle, and converging ventral ridges on posterior portion of anterior pterygoid rami. In Jimusaria, the epipterygoid posteromedially contacts the parabasisphenoid and the periotic as a rod-like bar, a unique morphology unknown in any other dicynodonts. This structure probably increases the stability of the palatal complex. A similar structure might also appear in other dicynodonts as a cartilage connection. The new occurrence of Jimusaria increases the diversity of the tetrapod assemblage from the Naobaogou Formation, and further strengthens the connection between the tetrapod faunas from Nei Mongol and Xinjiang. Based on the current record, Jimusaria is one of the few tetrapod genera which survived in the end-Permian mass extinction.
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Affiliation(s)
- Yu-Tai Shi
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
| | - Jun Liu
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
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5
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Sues HD, Schoch RR. A new Middle Triassic (Ladinian) trilophosaurid stem-archosaur from Germany increases diversity and temporal range of this clade. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230083. [PMID: 36968237 PMCID: PMC10031418 DOI: 10.1098/rsos.230083] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 02/28/2023] [Indexed: 06/18/2023]
Abstract
We report the first trilophosaurid stem-archosaur from Central Europe, Rutiotomodon tytthos gen. et sp. nov., from the Middle Triassic (Ladinian) Erfurt Formation of Baden-Württemberg (Germany). It is currently known from two jaw fragments with distinctive teeth. The labiolingually wide but mesiodistally narrow maxillary and dentary teeth each have a large labial cusp from which an occlusal ridge extends lingually to a small lingual cusp. A mesial and a distal cingulum extend between the labial and lingual cusps. The mesial and distal faces of the labial cusp each bear three prominent, lingually curved apicobasal ridges (arrises). A referred partial dentary has an edentulous, expanded symphysis similar to the mandibular 'beak' in Trilophosaurus buettneri. A review of Coelodontognathus ricovi, from the Lower Triassic (Olenekian) of southwestern Russia, supports its referral to Trilophosauridae rather than Procolophonidae. Based on this reassessment and the new material from the Middle Triassic, the temporal range of trilophosaurids now spans nearly the entire Triassic Period, from the Olenekian to the Rhaetian. Trilophosaurids present craniodental features that indicate omnivory or herbivory with limited oral food processing. They were more diverse in terms of dental structure (and presumably diet) than previously assumed.
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Affiliation(s)
- Hans-Dieter Sues
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Rainer R. Schoch
- Staatliches Museum für Naturkunde Stuttgart, Stuttgart, Germany
- Institut für Biologie, Universität Hohenheim, Stuttgart, Germany
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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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Liu J. The tetrapod fauna of the upper Permian Naobaogou Formation of China: 6. Turfanodon jiufengensis sp. nov. (Dicynodontia). PeerJ 2021; 9:e10854. [PMID: 33643709 PMCID: PMC7896508 DOI: 10.7717/peerj.10854] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 01/06/2021] [Indexed: 11/20/2022] Open
Abstract
The dicynodont fossils from the Naobaogou Formation of Nei Mongol, China are abundant and diverse but poorly studied. In this article, one nearly complete skeleton and four cranial specimens from the Naobaogou Formation are referred to the dicynodontoid genus Turfanodon as a new species, T. jiufengensis. Previously, Turfanodon was known only from upper Permian sites in Xinjiang and Gansu. The new specimens are referred to Turfanodon based on the following characters: snout tall with steeply sloping profile, anterior tip of the snout squared off, facial region heavily pitted, nasal bosses present as paired swellings near the posterodorsal margin of the external nares, preparietal depressed, intertemporal bar long and narrow, premaxilla contacting frontal, palatal surface of premaxilla exposed in lateral view, and anterior pterygoid keel restricted to the anterior tip of the anterior ramus of the pterygoid. Turfanodon jiufengensis is differentiated from the type species, T. bogdaensis, by a contact of the lacrimal with the septomaxilla, discrete, raised nasal bosses, the dorsal edge of the erupted portion of the canine tusk slightly posterior to the anterior orbital margin, an anterior extension of the lacrimal distinctly shorter than that of the prefrontal, and a premaxillary dorsal surface with a median ridge. The holotype skeleton of T. jiufengensis includes a complete axial column with 50 vertebrae (six cervical, 23 dorsal, six sacral, and 15 caudal). Turfanodon represents the first confirmed tetrapod genus shared by the late Permian faunas of the Junggar and Ordos basins, and appears to be the first dicynodont genus distributed across both tropical and temperate zones (based on paleoclimate reconstructions). Based on tetrapod fossil content, the Naobaogou Formation can be roughly correlated to the Daptocephalus Assemblage Zone of South Africa (255-252 Ma in age).
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Affiliation(s)
- Jun Liu
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing, China
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing, China
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9
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Sulej T, Niedźwiedzki G. An elephant-sized Late Triassic synapsid with erect limbs. Science 2018; 363:78-80. [PMID: 30467179 DOI: 10.1126/science.aal4853] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 08/04/2018] [Accepted: 10/19/2018] [Indexed: 11/02/2022]
Abstract
Here, we describe the dicynodont Lisowicia bojani, from the Late Triassic of Poland, a gigantic synapsid with seemingly upright subcursorial limbs that reached an estimated length of more than 4.5 meters, height of 2.6 meters, and body mass of 9 tons. Lisowicia is the youngest undisputed dicynodont and the largest nondinosaurian terrestrial tetrapod from the Triassic. The lack of lines of arrested growth and the highly remodeled cortex of its limb bones suggest permanently rapid growth and recalls that of dinosaurs and mammals. The discovery of Lisowicia overturns the established picture of the Triassic megaherbivore radiation as a phenomenon restricted to dinosaurs and shows that stem-group mammals were capable of reaching body sizes that were not attained again in mammalian evolution until the latest Eocene.
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Affiliation(s)
- Tomasz Sulej
- Institute of Paleobiology, Polish Academy of Sciences (PAS), Twarda 51/55, 00-818 Warsaw, Poland
| | - Grzegorz Niedźwiedzki
- Department of Organismal Biology, Uppsala University, Norbyvägen 18A, 752 36 Uppsala, Sweden.
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10
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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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11
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Liu J, Schneider VP, Olsen PE. The postcranial skeleton of Boreogomphodon (Cynodontia: Traversodontidae) from the Upper Triassic of North Carolina, USA and the comparison with other traversodontids. PeerJ 2017; 5:e3521. [PMID: 28929007 PMCID: PMC5601084 DOI: 10.7717/peerj.3521] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Accepted: 06/08/2017] [Indexed: 12/02/2022] Open
Abstract
Postcranial remains of Boreogomphodon from the Upper Triassic of North Carolina are described and compared to those of other known traversodontid cynodonts. The postcranial skeleton of Boreogomphodon is characterized by four sacral ribs, simple ribs lacking costal plates, the extension of the scapular neck below the acromion process, a short scapular facet on the procoracoid, a concave anterior margin of the procoracoid, humerus entepicondyle with smooth corner, and the presence of a fifth distal carpal. Four types of ribs are identified among traversodontids: ‘normal’ form, tubercular rib, costal plate, and Y-shaped rib. Fossorial behavior is suggested for traversodontids with elaborate costal plates. Within Traversodontidae, the procoracoid is relatively small; the anterior process of the iliac blade extends anteroventrally to different degrees in different taxa, which facilitates retraction of the femur; and the limb bones show allometric growth in terms of length and width.
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Affiliation(s)
- Jun Liu
- Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Vincent P Schneider
- North Carolina Museum of Natural Sciences, Raleigh, NC, United States of America
| | - Paul E Olsen
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, United States of America
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12
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Olivier C, Houssaye A, Jalil NE, Cubo J. First palaeohistological inference of resting metabolic rate in an extinct synapsid, Moghreberia nmachouensis (Therapsida: Anomodontia). Biol J Linn Soc Lond 2017. [DOI: 10.1093/biolinnean/blw044] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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13
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Kammerer CF, Smith RMH. An early geikiid dicynodont from the Tropidostoma Assemblage Zone (late Permian) of South Africa. PeerJ 2017; 5:e2913. [PMID: 28168104 PMCID: PMC5289114 DOI: 10.7717/peerj.2913] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 12/14/2016] [Indexed: 11/20/2022] Open
Abstract
Based on specimens previously identified as Tropidostoma, a new taxon of dicynodont (Bulbasaurus phylloxyron gen. et sp. nov.) from the Karoo Basin of South Africa is described. Bulbasaurus is a medium-sized dicynodont (maximum dorsal skull length 16.0 cm) restricted to the Tropidostoma Assemblage Zone (early Lopingian) of the Beaufort Group. Bulbasaurus can be distinguished from Tropidostoma by an array of characters including the presence of a tall, sharp premaxillary ridge, large, rugose, nearly-confluent nasal bosses, a nasofrontal ridge, massive tusks, robust pterygoids, prominently twisted subtemporal bar, and absence of a distinct postfrontal. Inclusion of Bulbasaurus in a phylogenetic analysis of anomodont therapsids recovers it as a member of Geikiidae, a clade of otherwise later Permian dicynodonts such as Aulacephalodon and Pelanomodon. Bulbasaurus exhibits many of the characters typical of adult Aulacephalodon, but at substantially smaller skull size (these characters are absent in comparably-sized Aulacephalodon juveniles), suggesting that the evolution of typical geikiid morphology preceded gigantism in the clade. Bulbasaurus is the earliest known geikiid and the only member of the group known from the Tropidostoma Assemblage Zone; discovery of this taxon shortens a perplexing ghost lineage and indicates that abundant clades from the later Permian of South Africa (e.g., Geikiidae, Dicynodontoidea) may have originated as rare components of earlier Karoo assemblage zones.
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Affiliation(s)
- Christian F Kammerer
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany; Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Roger M H Smith
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa; Iziko Museums of South Africa, Cape Town, South Africa
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14
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Boos ADS, Kammerer CF, Schultz CL, Soares MB, Ilha ALR. A New Dicynodont (Therapsida: Anomodontia) from the Permian of Southern Brazil and Its Implications for Bidentalian Origins. PLoS One 2016; 11:e0155000. [PMID: 27224287 PMCID: PMC4880204 DOI: 10.1371/journal.pone.0155000] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 04/22/2016] [Indexed: 01/17/2023] Open
Abstract
Dicynodonts were a highly successful group of herbivorous therapsids that inhabited terrestrial ecosystems from the Middle Permian through the end of the Triassic periods. Permian dicynodonts are extremely abundant in African deposits, but are comparatively poorly known from the other regions of Gondwana. Here we describe a new South American dicynodont, Rastodon procurvidens gen. et sp. nov., from the Boqueirão farm site of the Rio do Rasto Formation, Paraná Basin, Guadalupian/Lopingian of Brazil. Diagnostic features of R. procurvidens include uniquely anteriorly-curved maxillary tusks, well-developed ridges extending from the crista oesophagea anteriorly along the pterygoid rami, strong posterior angulation of the posterior pterygoid rami, and a bulbous, well-developed retroarticular process of the articular. Phylogenetic analysis indicates that R. procurvidens is the earliest and most basal member of Bidentalia, a cosmopolitan clade that includes Permian and Triassic dicynodonts whose dentition is usually reduced to a pair of maxillary tusks.
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Affiliation(s)
- Alessandra D. S. Boos
- Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
- Departamento de Ciências Naturais, Fundação Universidade Regional de Blumenau, Blumenau, Santa Catarina, Brazil
- * E-mail:
| | - Christian F. Kammerer
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
| | - Cesar L. Schultz
- Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Marina B. Soares
- Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Ana L. R. Ilha
- Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
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15
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Cisneros JC, Abdala F, Jashashvili T, de Oliveira Bueno A, Dentzien-Dias P. Tiarajudens eccentricus and Anomocephalus africanus, two bizarre anomodonts (Synapsida, Therapsida) with dental occlusion from the Permian of Gondwana. ROYAL SOCIETY OPEN SCIENCE 2015; 2:150090. [PMID: 26587266 PMCID: PMC4632579 DOI: 10.1098/rsos.150090] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 06/16/2015] [Indexed: 06/05/2023]
Abstract
Anomodontia was a highly successful tetrapod clade during the Permian and the Triassic. New morphological information regarding two bizarre basal anomodonts is provided and their palaeoecological significance is explored. The osteology of the recently discovered Tiarajudens eccentricus Cisneros et al. 2011, from the Brazilian Permian, is described in detail. The taxon exhibits unusual postcranial features, including the presence of gastralia. Additional preparation and computed tomography scans of the holotype of Anomocephalus africanus Modesto et al. 1999 discovered in the Karoo Basin of South Africa allow a reappraisal of this genus. Anomocephalus is similar to Tiarajudens with regard to several traits, including a battery of large, transversally expanded, palatal teeth. Molariform teeth are present in the mandible of the African taxon, providing additional insight into the function of the earliest tooth-occlusion mechanism known in therapsids. At least two waves of tooth replacement can be recognized in the palate of Anomocephalus. The outsized, blade-like caniniforms of the herbivorous Tiarajudens allow several non-exclusive ecological interpretations, among which we favour intraspecific display or combat. This behaviour was an alternative to the head-butting practised by the contemporary dinocephalians. Combat specializations that are considered typical of Cenozoic herbivores likely evolved during the Middle Permian, at the time the first communities with diverse, abundant tetrapod herbivores were being assembled.
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Affiliation(s)
| | - Fernando Abdala
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Tea Jashashvili
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
| | - Ana de Oliveira Bueno
- Departamento de Paleontologia e Estratigrafia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
| | - Paula Dentzien-Dias
- Laboratório de Paleontologia e Paleoceanografia, Universidade Federal do Rio Grande, Rio Grande, Brazil
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Mongiardino Koch N, Soto IM, Ramírez MJ. Overcoming problems with the use of ratios as continuous characters for phylogenetic analyses. ZOOL SCR 2015. [DOI: 10.1111/zsc.12120] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nicolás Mongiardino Koch
- Departamento de Ecología, Genética y Evolución; Facultad de Ciencias Exactas y Naturales; Universidad de Buenos Aires
- Instituto de Ecología; Genética y Evolución de Buenos Aires (IEGEBA - CONICET/UBA); Intendente Güiraldes 2160, Ciudad Universitaria (C1428 EHA); Capital Federal Buenos Aires Argentina
| | - Ignacio M. Soto
- Departamento de Ecología, Genética y Evolución; Facultad de Ciencias Exactas y Naturales; Universidad de Buenos Aires
- Instituto de Ecología; Genética y Evolución de Buenos Aires (IEGEBA - CONICET/UBA); Intendente Güiraldes 2160, Ciudad Universitaria (C1428 EHA); Capital Federal Buenos Aires Argentina
| | - Martín J. Ramírez
- Museo Argentino de Ciencias Naturales - CONICET; Ángel Gallardo 490 (C1405 DJR) Capital Federal Buenos Aires Argentina
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17
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Castanhinha R, Araújo R, Júnior LC, Angielczyk KD, Martins GG, Martins RMS, Chaouiya C, Beckmann F, Wilde F. Bringing dicynodonts back to life: paleobiology and anatomy of a new emydopoid genus from the Upper Permian of Mozambique. PLoS One 2013; 8:e80974. [PMID: 24324653 PMCID: PMC3852158 DOI: 10.1371/journal.pone.0080974] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 10/04/2013] [Indexed: 11/19/2022] Open
Abstract
Dicynodontia represent the most diverse tetrapod group during the Late Permian. They survived the Permo-Triassic extinction and are central to understanding Permo-Triassic terrestrial ecosystems. Although extensively studied, several aspects of dicynodont paleobiology such as, neuroanatomy, inner ear morphology and internal cranial anatomy remain obscure. Here we describe a new dicynodont (Therapsida, Anomodontia) from northern Mozambique: Niassodon mfumukasi gen. et sp. nov. The holotype ML1620 was collected from the Late Permian K5 formation, Metangula Graben, Niassa Province northern Mozambique, an almost completely unexplored basin and country for vertebrate paleontology. Synchrotron radiation based micro-computed tomography (SRµCT), combined with a phylogenetic analysis, demonstrates a set of characters shared with Emydopoidea. All individual bones were digitally segmented allowing a 3D visualization of each element. In addition, we reconstructed the osseous labyrinth, endocast, cranial nerves and vasculature. The brain is narrow and the cerebellum is broader than the forebrain, resembling the conservative, "reptilian-grade" morphology of other non-mammalian therapsids, but the enlarged paraflocculi occupy the same relative volume as in birds. The orientation of the horizontal semicircular canals indicates a slightly more dorsally tilted head posture than previously assumed in other dicynodonts. In addition, synchrotron data shows a secondary center of ossification in the femur. Thus ML1620 represents, to our knowledge, the oldest fossil evidence of a secondary center of ossification, pushing back the evolutionary origins of this feature. The fact that the specimen represents a new species indicates that the Late Permian tetrapod fauna of east Africa is still incompletely known.
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Affiliation(s)
- Rui Castanhinha
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
- Museu da Lourinhã, Lourinhã, Portugal
| | - Ricardo Araújo
- Museu da Lourinhã, Lourinhã, Portugal
- Huffington Department of Earth Sciences, Southern Methodist University, Dallas, Texas, United States of America
| | | | - Kenneth D. Angielczyk
- Integrative Research Center, Field Museum of Natural History, Chicago, Illinois, United States of America
| | - Gabriel G. Martins
- Centro de Biologia Ambiental, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Rui M. S. Martins
- Museu da Lourinhã, Lourinhã, Portugal
- Campus Tecnológico e Nuclear, Instituto Superior Técnico, Bobadela, Portugal
- Centro de Investigação em Materiais, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Caparica, Portugal
- Centro de Física Nuclear da Universidade de Lisboa, Lisboa, Portugal
| | | | | | - Fabian Wilde
- Helmholtz-Zentrum Geesthacht, Geesthacht, Germany
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