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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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2
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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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3
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Bendel EM, Kammerer CF, Smith RMH, Fröbisch J. The postcranial anatomy of Gorgonops torvus (Synapsida, Gorgonopsia) from the late Permian of South Africa. PeerJ 2023; 11:e15378. [PMID: 37434869 PMCID: PMC10332358 DOI: 10.7717/peerj.15378] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 04/18/2023] [Indexed: 07/13/2023] Open
Abstract
Gorgonopsians are among the most recognizable groups of synapsids from the Permian period and have an extensive but mostly cranial fossil record. By contrast, relatively little is known about their postcranial anatomy. Here, we describe a nearly complete, semi-articulated skeleton of a gorgonopsian (identified as Gorgonops torvus) from the late Permian Endothiodon Assemblage Zone of the South African Karoo Basin and discuss its paleobiological implications. Known gorgonopsian postcrania indicate morphological conservatism in the group, but the skeletal anatomy of Gorgonops does differ from that of other gorgonopsians in some respects, such as in the triangular radiale and short terminal phalanges in the manus, and a weakly developed distinction between pubis and ischium in ventral aspect of the pelvic girdle. Similarities between the specimen described herein and a historically problematic specimen originally referred to "Scymnognathus cf. whaitsi" confirm referral of the latter specimen to Gorgonops. Since descriptions of gorgonopsian postcrania are rare, new interpretations of the lifestyle and ecology of Gorgonopsia can be drawn from our contribution. We conclude that gorgonopsians were likely ambush predators, able to chase their prey over short distances and pin them down with strong forelimbs before using their canines for the kill. This is evidenced by their different fore- and hindlimb morphology; the former stouter and more robust in comparison to the longer, more gracile, back legs. Furthermore, the completeness of the study specimen facilitates calculation of an estimated body mass of approximately 98 kg, similar to that of a modern lioness.
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Affiliation(s)
- Eva-Maria Bendel
- Institut für Biologie, Humboldt Universität zu Berlin, Berlin, Germany
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
| | - Christian F. Kammerer
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
- North Carolina Museum of Natural Sciences, Raleigh, North Carolina, United States of America
| | - Roger M. H. Smith
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
- Department of Karoo Palaeontology, Iziko South African Museum, Cape Town, South Africa
| | - Jörg Fröbisch
- Institut für Biologie, Humboldt Universität zu Berlin, Berlin, Germany
- Evolutionary Studies Institute, University of the Witwatersrand, Johannesburg, South Africa
- Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Museum für Naturkunde, Berlin, Germany
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4
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Bazzana-Adams KD, Evans DC, Reisz RR. Neurosensory anatomy and function in Dimetrodon, the first terrestrial apex predator. iScience 2023; 26:106473. [PMID: 37096050 PMCID: PMC10122045 DOI: 10.1016/j.isci.2023.106473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 02/16/2023] [Accepted: 03/19/2023] [Indexed: 04/05/2023] Open
Abstract
Dimetrodon is among the most recognizable fossil taxa, as well as the earliest terrestrial amniote apex predator. The neuroanatomy and auditory abilities of Dimetrodon has long been the subject of interest, but palaeoneurological analyses have been limited by the lack of three-dimensional endocast data. The first virtual endocasts reveal a strongly flexed brain with enlarged floccular fossae and a surprisingly well-ossified bony labyrinth clearly preserving the semicircular canals, along with an undifferentiated vestibule and putative perilymphatic duct. This first detailed palaeoneurological reconstruction reveals potential adaptations for a predatory lifestyle and suggests Dimetrodon was able to hear a wider range of frequencies than anticipated, potentially being sensitive to frequencies equal to or higher than many extant sauropsids, despite lacking an impedance matching ear. Ancestral state reconstructions support the long-standing view of Dimetrodon as representative of the ancestral state for therapsids, while underscoring the importance of validating reconstructive analyses with fossil data.
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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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6
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Bazzana KD, Evans DC, Bevitt JJ, Reisz RR. Neurosensory anatomy of Varanopidae and its implications for early synapsid evolution. J Anat 2022; 240:833-849. [PMID: 34775594 PMCID: PMC9005680 DOI: 10.1111/joa.13593] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 11/04/2021] [Accepted: 11/04/2021] [Indexed: 12/11/2022] Open
Abstract
Varanopids are a group of Palaeozoic terrestrial amniotes which represent one of the earliest-diverging groups of synapsids, but their palaeoneurology has gone largely unstudied and recent analyses have challenged their traditional placement within synapsids. We utilized computed tomography (CT) to study the virtual cranial and otic endocasts of six varanopids, including representative taxa of both mycterosaurines and varanodontines. Our results show that the varanopid brain is largely plesiomorphic, being tubular in shape and showing no expansion of the cerebrum or olfactory bulbs, but is distinct in showing highly expanded floccular fossae. The housing of the varanopid bony labyrinth is also distinct, in that the labyrinth is bounded almost entirely by the supraoccipital-opisthotic complex, with the prootic only bordering the ventral portion of the vestibule. The bony labyrinth is surprisingly well-ossified, clearly preserving the elliptical, sub-orthogonal canals, prominent ampullae, and the short, undifferentiated vestibule; this high degree of ossification is similar to that seen in therapsid synapsids and supports the traditional placement of varanopids within Synapsida. The enlarged anterior canal, together with the elliptical, orthogonal canals and enlarged floccular fossa, lend support for the fast head movements indicated by the inferred predatory feeding mode of varanopids. Reconstructed neurosensory anatomy indicates that varanopids may have a much lower-frequency hearing range compared to more derived synapsids, suggesting that, despite gaining some active predatory features, varanopids retain plesiomorphic hearing capabilities. As a whole, our data reveal that the neuroanatomy of pelycosaur-grade synapsids is far more complex than previously anticipated.
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Affiliation(s)
- Kayla D. Bazzana
- Department of BiologyUniversity of Toronto MississaugaMississaugaCanada
- Department of Natural HistoryRoyal Ontario MuseumTorontoCanada
| | - David C. Evans
- Department of Natural HistoryRoyal Ontario MuseumTorontoCanada
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoCanada
| | - Joseph J. Bevitt
- Australian Centre for Neutron ScatteringAustralian Nuclear Science and Technology OrganisationLucas HeightsNew South WhalesAustralia
| | - Robert R. Reisz
- Department of BiologyUniversity of Toronto MississaugaMississaugaCanada
- International Center of Future ScienceDinosaur Evolution Research CenterJilin UniversityChangchunJilin ProvinceChina
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7
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8
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Kulik ZT, Lungmus JK, Angielczyk KD, Sidor CA. Living fast in the Triassic: New data on life history in Lystrosaurus (Therapsida: Dicynodontia) from northeastern Pangea. PLoS One 2021; 16:e0259369. [PMID: 34739492 PMCID: PMC8570511 DOI: 10.1371/journal.pone.0259369] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 10/19/2021] [Indexed: 11/29/2022] Open
Abstract
Lystrosaurus was one of the few tetrapods to survive the Permo-Triassic mass extinction, the most profound biotic crisis in Earth’s history. The wide paleolatitudinal range and high abundance of Lystrosaurus during the Early Triassic provide a unique opportunity to investigate changes in growth dynamics and longevity following the mass extinction, yet most studies have focused only on species that lived in the southern hemisphere. Here, we present the long bone histology from twenty Lystrosaurus skeletal elements spanning a range of sizes that were collected in the Jiucaiyuan Formation of northwestern China. In addition, we compare the average body size of northern and southern Pangean Triassic-aged species and conduct cranial geometric morphometric analyses of southern and northern taxa to begin investigating whether specimens from China are likely to be taxonomically distinct from South African specimens. We demonstrate that Lystrosaurus from China have larger average body sizes than their southern Pangean relatives and that their cranial morphologies are distinctive. The osteohistological examination revealed sustained, rapid osteogenesis punctuated by growth marks in some, but not all, immature individuals from China. We find that the osteohistology of Chinese Lystrosaurus shares a similar growth pattern with South African species that show sustained growth until death. However, bone growth arrests more frequently in the Chinese sample. Nevertheless, none of the long bones sampled here indicate that maximum or asymptotic size was reached, suggesting that the maximum size of Lystrosaurus from the Jiucaiyuan Formation remains unknown.
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Affiliation(s)
- Zoe T. Kulik
- Department of Biology and Burke Museum, University of Washington, Seattle, WA, United States of America
- * E-mail:
| | - Jacqueline K. Lungmus
- Smithsonian National Museum of Natural History, Washington, D.C., United States of America
| | - Kenneth D. Angielczyk
- Negaunee Integrative Research Center, Field Museum of Natural History, Chicago, IL, United States of America
| | - Christian A. Sidor
- Department of Biology and Burke Museum, University of Washington, Seattle, WA, United States of America
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9
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Pusch LC, Kammerer CF, Fröbisch J. Cranial anatomy of Bolotridon frerensis, an enigmatic cynodont from the Middle Triassic of South Africa, and its phylogenetic significance. PeerJ 2021; 9:e11542. [PMID: 34178451 PMCID: PMC8214396 DOI: 10.7717/peerj.11542] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 05/10/2021] [Indexed: 01/17/2023] Open
Abstract
The cynodont fauna of the Trirachodon-Kannemeyeria Subzone of the Middle Triassic Cynognathus Assemblage Zone (AZ) is almost exclusively represented by taxa belonging to the clade Eucynodontia. However, there is one basal (non-eucynodont) cynodont known to have survived into this assemblage: the enigmatic Bolotridon frerensis. BSPG 1934-VIII-7 represents by far the most extensive specimen of B. frerensis, consisting of a partial skull with occluded lower jaw. The specimen was initially described by Broili & Schröder (1934), but their description was limited to surface details of the skull and the dental morphology. Here, by using a computed tomographic (CT) reconstruction, we redescribe this specimen, providing novel information on its palatal and internal anatomy. New endocranial characters recognized for this taxon include ridges in the nasal cavity indicating the presence of cartilaginous respiratory turbinals. New data obtained from the CT scan were incorporated into the most recently published data matrix of early non-mammalian cynodonts to test the previously unstable phylogenetic position of Bolotridon. Our phylogenetic analyses recovered Bolotridon as the sister-taxon of Eucynodontia, a more crownward position than previously hypothesized.
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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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10
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Whitney MR, LeBlanc ARH, Reynolds AR, Brink KS. Convergent dental adaptations in the serrations of hypercarnivorous synapsids and dinosaurs. Biol Lett 2020; 16:20200750. [PMID: 33321067 DOI: 10.1098/rsbl.2020.0750] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Theropod dinosaurs are well known for having a ziphodont dentition: serrated, blade-shaped teeth that they used for cutting through prey. Serrations along the carinae of theropod teeth are composed of true denticles, a complex arrangement of dentine, enamel, and interdental folds. This structure would have supported individual denticles and dissipated the stresses associated with feeding. These particular serrations were previously thought to be unique to theropod dinosaurs and some other archosaurs. Here, we identify the same denticles and interdental folds forming the cutting edges in the teeth of a Permian gorgonopsian synapsid, extending the temporal and phylogenetic distribution of this dental morphology. This remarkable instance of convergence not only represents the earliest record of this adaptation to hypercarnivory but also demonstrates that the first iteration of this feature appeared in non-mammalian synapsids. Comparisons of tooth serrations in gorgonopsians with those of earlier synapsids and hypercarnivorous mammals reveal some gorgonopsians acquired a complex tissue arrangement that differed from other synapsids.
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Affiliation(s)
- M R Whitney
- Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138, USA
| | - A R H LeBlanc
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9
| | - A R Reynolds
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada M5S 3B2
| | - K S Brink
- Department of Geological Sciences, University of Manitoba, 125 Dysart Road, Winnipeg, Manitoba, Canada R3T 2N2
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11
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A test of the lateral semicircular canal correlation to head posture, diet and other biological traits in "ungulate" mammals. Sci Rep 2020; 10:19602. [PMID: 33177568 PMCID: PMC7658238 DOI: 10.1038/s41598-020-76757-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 11/02/2020] [Indexed: 02/08/2023] Open
Abstract
For over a century, researchers have assumed that the plane of the lateral semicircular canal of the inner ear lies parallel to the horizon when the head is at rest, and used this assumption to reconstruct head posture in extinct species. Although this hypothesis has been repeatedly questioned, it has never been tested on a large sample size and at a broad taxonomic scale in mammals. This study presents a comprehensive test of this hypothesis in over one hundred "ungulate" species. Using CT scanning and manual segmentation, the orientation of the skull was reconstructed as if the lateral semicircular canal of the bony labyrinth was aligned horizontally. This reconstructed cranial orientation was statistically compared to the actual head posture of the corresponding species using a dataset of 10,000 photographs and phylogenetic regression analysis. A statistically significant correlation between the reconstructed cranial orientation and head posture is found, although the plane of the lateral semicircular canal departs significantly from horizontal. We thus caution against the use of the lateral semicircular canal as a proxy to infer precisely the horizontal plane on dry skulls and in extinct species. Diet (browsing or grazing) and head-butting behaviour are significantly correlated to the orientation of the lateral semicircular canal, but not to the actual head posture. Head posture and the orientation of the lateral semicircular canal are both strongly correlated with phylogenetic history.
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12
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Pusch LC, Ponstein J, Kammerer CF, Fröbisch J. Novel Endocranial Data on the Early Therocephalian Lycosuchus vanderrieti Underpin High Character Variability in Early Theriodont Evolution. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2019.00464] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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13
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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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14
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Bullar CM, Zhao Q, Benton MJ, Ryan MJ. Ontogenetic braincase development in Psittacosaurus lujiatunensis (Dinosauria: Ceratopsia) using micro-computed tomography. PeerJ 2019; 7:e7217. [PMID: 31428535 PMCID: PMC6698140 DOI: 10.7717/peerj.7217] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 05/31/2019] [Indexed: 11/20/2022] Open
Abstract
Ontogenetic sequences are relatively rare among dinosaurs, with Ceratopsia being one of the better represented clades, and especially among geologically earlier forms, such as Psittacosaurus. Psittacosaurus is a small, bipedal basal ceratopsian abundant in the Lower Cretaceous deposits of Asia, whose cranial and endocranial morphology has been well studied, but only cursory details have been published on the bones surrounding the brain. Using reconstructions created from micro-computed tomography scans of well-preserved skulls from the Barremian–Aptian Yixian Formation, China, we document morphological changes in the braincase of Psittacosaurus lujiatunensis through three growth stages, hatchling, juvenile, and adult, thus providing the first detailed study of ceratopsian braincase morphology through ontogeny. Notable ontogenetic changes in the braincase of P. lujiatunensis include a dramatic relative reduction in size of the supraoccipital, an increase in the lateral expansion of the paroccipital processes and a decrease in the angle between the lateral semicircular canal and the palatal plane. These ontogenetic morphological changes in the braincase relate to expansion of the cranium and brain through growth, as well as reflecting the switch from quadrupedal juveniles to bipedal adults as documented in the changing orientation of the horizontal semicircular canal through ontogeny. Recognition of these patterns in a basal ceratopsian has implications for understanding key events in later ceratopsian evolution, such as the development of the parieto-squamosal frill in derived neoceratopsians.
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Affiliation(s)
- Claire M Bullar
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - Qi Zhao
- School of Earth Sciences, University of Bristol, Bristol, UK.,Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
| | | | - Michael J Ryan
- Department of Earth Sciences, Carleton University, Ottawa, ON, Canada
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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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16
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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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17
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Bendel EM, Kammerer CF, Kardjilov N, Fernandez V, Fröbisch J. Cranial anatomy of the gorgonopsian Cynariops robustus based on CT-reconstruction. PLoS One 2018; 13:e0207367. [PMID: 30485338 PMCID: PMC6261584 DOI: 10.1371/journal.pone.0207367] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 10/30/2018] [Indexed: 11/19/2022] Open
Abstract
Gorgonopsia is one of the major clades of non-mammalian synapsids, and includes an array of large-bodied carnivores that were the top terrestrial predators of the late Permian. Most research on the clade has focused on these largest members; small-bodied gorgonopsians are relatively little-studied. Here, we redescribe a small gorgonopsian skull (MB.R.999) from the late Permian (Tropidostoma Assemblage Zone) of South Africa on the basis of neutron and synchrotron CT reconstructions, which yield new data on internal cranial morphology in Gorgonopsia. Because of the largely undistorted nature of MB.R.999, we were also able to reconstruct unossified areas such as the brain endocast and the otic labyrinth. MB.R.999 can be referred to the taxon Cynariops robustus based on its general skull proportions, postcanine tooth count, preparietal morphology, and vomerine morphology. We refer additional small gorgonopsian specimens from the Victoria West area to Cynariops robustus, and consider Cynarioides grimbeeki and Cynarioides laticeps to be synonymous with C. robustus. Inclusion of Cynariops in a phylogenetic analysis of Gorgonopsia recovers it within a large clade of African taxa, more closely related to Lycaenops and rubidgeines than Eriphostoma or Gorgonops.
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Affiliation(s)
- Eva-Maria Bendel
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
| | - Christian F. Kammerer
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
- North Carolina Museum of Natural Sciences, Raleigh, NC, United States of America
- Evolutionary Studies Institute & School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Nikolay Kardjilov
- Helmholtz-Zentrum Berlin–Institute of Applied Materials, Berlin, Germany
| | - Vincent Fernandez
- Imaging and Analysis Centre, The Natural History Museum, London, United Kingdom
- European Synchrotron Radiation Facility, Grenoble, France
| | - Jörg Fröbisch
- Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Berlin, Germany
- Evolutionary Studies Institute & School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
- Institut für Biologie, Humboldt-Universität zu Berlin, Berlin, Germany
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18
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Maggio LA, Leroux TC, Meyer HS, Artino AR. #MedEd: exploring the relationship between altmetrics and traditional measures of dissemination in health professions education. PERSPECTIVES ON MEDICAL EDUCATION 2018; 7:239-247. [PMID: 29949099 PMCID: PMC6086816 DOI: 10.1007/s40037-018-0438-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
INTRODUCTION Researchers, funders, and institutions are interested in understanding and quantifying research dissemination and impact, particularly related to communicating with the public. Traditionally, citations have been a primary impact measure; however, citations can be slow to accrue and focus on academic use. Recently altmetrics, which track alternate dissemination forms (e. g., social media), have been suggested as a complement to citation-based metrics. This study examines the relationship between altmetrics and traditional measures: journal article citations and access counts. METHODS The researchers queried Web of Science and Altmetric Explorer for articles published in HPE journals between 2013-2015. They identified 2,486 articles with altmetrics. Data were analyzed using negative binomial and linear regression models. RESULTS Blogging was associated with the greatest increase in citations (13% increase), whereas Tweets (1.2%) and Mendeley (1%) were associated with smaller increases. Journal impact factor (JIF) was associated with a 21% increase in citations. Publicly accessible articles were associated with a 19% decrease, but the interactive effect between accessible articles and JIF was associated with a 12% increase. When examining access counts, publicly accessible articles had an increase of 170 access counts whereas blogging was associated with a decrease of 87 accesses. DISCUSSION This study suggests that several altmetrics outlets are positively associated with citations, and that public accessibility, holding all other independent variables constant, is positively related to article access. Given the scientific community's evolving focus on dissemination these findings have implications for stakeholders, providing insight into the factors that may improve citations and access of articles.
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Affiliation(s)
- Lauren A Maggio
- Division of Health Professions Education, Department of Medicine, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.
| | - Todd C Leroux
- Division of Health Services Administration, Department of Preventive Medicine and Biostatistics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Holly S Meyer
- Division of Health Professions Education, Department of Medicine, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Anthony R Artino
- Division of Health Professions Education, Department of Medicine, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
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Abstract
The semicircular canal (SC) system of the inner ear detects head angular accelerations and is essential for navigation and spatial awareness in vertebrates. Because the bony labyrinth encloses the membranous labyrinth SCs, it can be used as a proxy for animal behavior. The bony labyrinth of dicynodonts, a clade of herbivorous non-mammalian synapsids, has only been described in a handful of individuals and remains particularly obscure. Here we describe the bony labyrinth anatomy of three Endothiodon cf. bathystoma specimens from Mozambique based on digital reconstructions from propagation phase-contrast synchrotron micro-computed tomography. We compare these findings with the bony labyrinth anatomy of their close relative Niassodon. The bony labyrinths of Endothiodon and Niassodon are relatively similar and show only differences in the shape of the horizontal SCs and the orientation of the vertical SCs. When compared to extant mammals, Endothiodon and Niassodon have highly eccentric SCs. In addition, the Endothiodon SCs are nearly orthogonal. An eccentric and orthogonal SC morphology is consistent with a specialization in rapid head movements, which are typical of foraging or feeding behaviors. Furthermore, we estimate the body mass of these Endothiodon specimens at ~116 to 182 kg, based on the average SC radii calculated using a linear regression model optimized by the Amemiya Prediction Criterion. Our findings provide novel insights into the paleobiology of Endothiodon which are consistent with the peculiar feeding mechanism among dicynodonts presumed from their multiple postcanine toothrows.
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Lautenschlager S, Ferreira GS, Werneburg I. Sensory Evolution and Ecology of Early Turtles Revealed by Digital Endocranial Reconstructions. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00007] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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21
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Schellhorn R. A potential link between lateral semicircular canal orientation, head posture, and dietary habits in extant rhinos (Perissodactyla, Rhinocerotidae). J Morphol 2017; 279:50-61. [DOI: 10.1002/jmor.20753] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 08/18/2017] [Accepted: 08/26/2017] [Indexed: 11/10/2022]
Affiliation(s)
- Rico Schellhorn
- Steinmann-Institut für Geologie, Mineralogie und Paläontologie, Rheinische Friedrich-Wilhelms-Universität Bonn, Nussallee 8; Bonn 53115 Germany
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Benoit J, Manger PR, Norton L, Fernandez V, Rubidge BS. Synchrotron scanning reveals the palaeoneurology of the head-butting Moschops capensis (Therapsida, Dinocephalia). PeerJ 2017; 5:e3496. [PMID: 28828230 PMCID: PMC5554600 DOI: 10.7717/peerj.3496] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 06/02/2017] [Indexed: 12/17/2022] Open
Abstract
Dinocephalian therapsids are renowned for their massive, pachyostotic and ornamented skulls adapted for head-to-head fighting during intraspecific combat. Synchrotron scanning of the tapinocephalid Moschops capensis reveals, for the first time, numerous anatomical adaptations of the central nervous system related to this combative behaviour. Many neural structures (such as the brain, inner ear and ophthalmic branch of the trigeminal nerve) were completely enclosed and protected by bones, which is unusual for non-mammaliaform therapsids. The nearly complete ossification of the braincase enables precise determination of the brain cavity volume and encephalization quotient, which appears greater than expected for such a large and early herbivore. The practice of head butting is often associated with complex social behaviours and gregariousness in extant species, which are known to influence brain size evolution. Additionally, the plane of the lateral (horizontal) semicircular canal of the bony labyrinth is oriented nearly vertically if the skull is held horizontally, which suggests that the natural position of the head was inclined about 60–65°to the horizontal. This is consistent with the fighting position inferred from osteology, as well as ground-level browsing. Finally, the unusually large parietal tube may have been filled with thick conjunctive tissue to protect the delicate pineal eye from injury sustained during head butting.
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Affiliation(s)
- Julien Benoit
- Evolutionary Institute, School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa.,School of Anatomical Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Paul R Manger
- School of Anatomical Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Luke Norton
- Evolutionary Institute, School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Vincent Fernandez
- Beamline ID19, European Synchrotron Radiation Facility, Grenoble, France
| | - Bruce S Rubidge
- Evolutionary Institute, School of Geosciences, University of the Witwatersrand, Johannesburg, South Africa
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