1
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Sues HD, Schoch RR. The oldest known rhynchocephalian reptile from the Middle Triassic (Ladinian) of Germany and its phylogenetic position among Lepidosauromorpha. Anat Rec (Hoboken) 2024; 307:776-790. [PMID: 37937325 DOI: 10.1002/ar.25339] [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: 08/11/2023] [Revised: 09/25/2023] [Accepted: 10/02/2023] [Indexed: 11/09/2023]
Abstract
Skeletal remains of a small lepidosaurian reptile from the Middle Triassic (Ladinian: Longobardian) Erfurt Formation, exposed in a commercial limestone quarry near Vellberg (Germany), represent the oldest rhynchocephalian known to date. The new taxon, Wirtembergia hauboldae, is diagnosed by the following combination of features: Premaxilla with four teeth, first being largest and decreasing in size from first to fourth. Jugal with tiny, spur-like posterior process. Lateral surface of dentary strongly convex dorsoventrally for much of length of bone, bearing distinct longitudinal ridge and sculpturing in large specimens. Coronoid eminence of dentary low, subrectangular, and with dorsoventrally concave lateral surface in larger specimens. Dentition with pleurodont anterior and acrodont posterior teeth. Posterior (=additional) teeth with (in side view) triangular, at mid-crown level labiolingually somewhat flattened crowns, and with oval bases. Phylogenetic analysis recovered the new rhynchocephalian as the earliest-diverging member of its clade known to date.
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Affiliation(s)
- Hans-Dieter Sues
- Department of Paleobiology, National Museum of Natural History, Washington, DC, USA
| | - Rainer R Schoch
- Staatliches Museum für Naturkunde Stuttgart, Stuttgart, Germany
- Institut für Biologie, Fachgebiet Paläontologie, Universität Hohenheim, Stuttgart, Germany
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2
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Roese-Miron L, Jones MEH, Ferreira JD, Hsiou AS. Virtual endocasts of Clevosaurus brasiliensis and the tuatara: Rhynchocephalian neuroanatomy and the oldest endocranial record for Lepidosauria. Anat Rec (Hoboken) 2024; 307:1366-1389. [PMID: 36951279 DOI: 10.1002/ar.25212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 03/02/2023] [Accepted: 03/07/2023] [Indexed: 03/24/2023]
Abstract
Understanding the origins of the vertebrate brain is fundamental for uncovering evolutionary patterns in neuroanatomy. Regarding extinct species, the anatomy of the brain and other soft tissues housed in endocranial spaces can be approximated by casts of these cavities (endocasts). The neuroanatomical knowledge of Rhynchocephalia, a reptilian clade exceptionally diverse in the early Mesozoic, is restricted to the brain of its only living relative, Sphenodon punctatus, and unknown for fossil species. Here, we describe the endocast and the reptilian encephalization quotient (REQ) of the Triassic rhynchocephalian Clevosaurus brasiliensis and compare it with an ontogenetic series of S. punctatus. To better understand the informative potential of endocasts in Rhynchocephalia, we also examine the brain-endocast relationship in S. punctatus. We found that the brain occupies 30% of its cavity, but the latter recovers the general shape and length of the brain. The REQ of C. brasiliensis (0.27) is much lower than S. punctatus (0.84-1.16), with the tuatara being close to the mean for non-avian reptiles. The endocast of S. punctatus is dorsoventrally flexed and becomes more elongated throughout ontogeny. The endocast of C. brasiliensis is mostly unflexed and tubular, possibly representing a more plesiomorphic anatomy in relation to S. punctatus. Given the small size of C. brasiliensis, the main differences may result from allometric and heterochronic phenomena, consistent with suggestions that S. punctatus shows peramorphic anatomy compared to Mesozoic rhynchocephalians. Our results highlight a previously undocumented anatomical diversity among rhynchocephalians and provide a framework for future neuroanatomical comparisons among lepidosaurs.
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Affiliation(s)
- Lívia Roese-Miron
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Marc Emyr Huw Jones
- Science Group: Fossil Reptiles, Amphibians and Birds Section, Natural History Museum, London, UK
- Research Department of Cell and Developmental Biology, University College London, London, UK
- School of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - José Darival Ferreira
- Programa de Pós-Graduação em Biodiversidade Animal, Universidade Federal de Santa Maria, Santa Maria, Brazil
| | - Annie Schmaltz Hsiou
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
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3
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Singh YP, Sharma KM, Tiwari RP, Patnaik R, Singh NA, Singh NP. Lepidosauromorphs and associated vertebrate fauna from the Late Triassic Tiki Formation, South Rewa, Gondwana basin, India: implication for paleoenvironment and paleobiogeography. PROCEEDINGS OF THE INDIAN NATIONAL SCIENCE ACADEMY 2023. [DOI: 10.1007/s43538-023-00162-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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4
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An exceptionally preserved Sphenodon-like sphenodontian reveals deep time conservation of the tuatara skeleton and ontogeny. Commun Biol 2022; 5:195. [PMID: 35241764 PMCID: PMC8894340 DOI: 10.1038/s42003-022-03144-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 02/09/2022] [Indexed: 11/09/2022] Open
Abstract
Sphenodontian reptiles are an extremely old evolutionary lineage forming the closest relatives to squamates (lizards and snakes) and were globally distributed and more diverse than squamates during the first half of their evolutionary history. However, the majority of their fossils are highly fragmentary, especially within sphenodontines-the group including its single surviving species, Sphenodon punctatus (the tuatara of New Zealand)-thus severely hampering our understanding on the origins of the tuatara. Here, we present a new sphenodontian species from the Early Jurassic of North America (Arizona, USA) represented by a nearly complete articulated skeleton and dozens of upper and lower jaws forming the most complete ontogenetic series in the sphenodontian fossil record. CT-scanning provides plentitude of data that unambiguously place this new taxon as one of the earliest evolving and oldest known sphenodontines. Comparisons with Sphenodon reveal that fundamental patterns of mandibular ontogeny and skeletal architecture in Sphenodon may have originated at least ~190Mya. In combination with recent findings, our results suggest strong morphological stability and an ancient origin of the modern tuatara morphotype.
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5
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Isip JE, Jones MEH, Cooper N. Clade-wide variation in bite-force performance is determined primarily by size, not ecology. Proc Biol Sci 2022; 289:20212493. [PMID: 35193399 PMCID: PMC8864353 DOI: 10.1098/rspb.2021.2493] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Performance traits are tightly linked to the fitness of organisms. However, because studies of variation in performance traits generally focus on just one or several closely related species, we are unable to draw broader conclusions about how and why these traits vary across clades. One important performance trait related to many aspects of an animal's life history is bite-force. Here, we use a clade-wide phylogenetic comparative approach to investigate relationships between size, head dimensions and bite-force among lizards and tuatara (lepidosaurs), using the largest bite-force dataset collated to date for any taxonomic group. We test four predictions: that bite-force will be greater in larger species, and for a given body size, bite-force will be greatest in species with acrodont tooth attachment, herbivorous diets, and non-burrowing habits. We show that bite-force is strongly related to body and head size across lepidosaurs and, as predicted, larger species have the greatest bite-forces. Contrary to our other predictions, tooth attachment, diet and habit have little predictive power when accounting for size. Herbivores bite more forcefully simply because they are larger. Our results also highlight priorities for future sampling to further enhance our understanding of broader evolutionary patterns.
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Affiliation(s)
- Justin E. Isip
- Department of Life Sciences, Natural History Museum London, Cromwell Road, London SW7 5BD, UK,Department of Life Sciences (Silwood Park), Imperial College London, Ascot, UK
| | - Marc E. H. Jones
- Research Department of Cell and Developmental Biology, Anatomy Building, University College London, Gower Street, London WCIE 6BT, UK,Department of Biological Sciences, The University of Adelaide, Adelaide, South Australia, Australia
| | - Natalie Cooper
- Department of Life Sciences, Natural History Museum London, Cromwell Road, London SW7 5BD, UK
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6
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Melstrom KM, Angielczyk KD, Ritterbush KA, Irmis RB. The limits of convergence: the roles of phylogeny and dietary ecology in shaping non-avian amniote crania. ROYAL SOCIETY OPEN SCIENCE 2021; 8:202145. [PMID: 34540239 PMCID: PMC8441121 DOI: 10.1098/rsos.202145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 08/17/2021] [Indexed: 05/28/2023]
Abstract
Cranial morphology is remarkably varied in living amniotes and the diversity of shapes is thought to correspond with feeding ecology, a relationship repeatedly demonstrated at smaller phylogenetic scales, but one that remains untested across amniote phylogeny. Using a combination of morphometric methods, we investigate the links between phylogenetic relationships, diet and skull shape in an expansive dataset of extant toothed amniotes: mammals, lepidosaurs and crocodylians. We find that both phylogeny and dietary ecology have statistically significant effects on cranial shape. The three major clades largely partition morphospace with limited overlap. Dietary generalists often occupy clade-specific central regions of morphospace. Some parallel changes in cranial shape occur in clades with distinct evolutionary histories but similar diets. However, members of a given clade often present distinct cranial shape solutions for a given diet, and the vast majority of species retain the unique aspects of their ancestral skull plan, underscoring the limits of morphological convergence due to ecology in amniotes. These data demonstrate that certain cranial shapes may provide functional advantages suited to particular dietary ecologies, but accounting for both phylogenetic history and ecology can provide a more nuanced approach to inferring the ecology and functional morphology of cryptic or extinct amniotes.
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Affiliation(s)
- Keegan M. Melstrom
- Dinosaur Institute, Natural History Museum of Los Angeles County, 900 W Exposition Boulevard, Los Angeles, CA 90007, USA
- Department of Geology and Geophysics, University of Utah, 115 S 1460 E, Salt Lake City, UT 84112-0102, USA
- Natural History Museum of Utah, University of Utah, 301 Wakara Way, Salt Lake City, UT 84108-1214, USA
| | - Kenneth D. Angielczyk
- Negaunee Integrative Research Center, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, IL 60605-2496, USA
| | - Kathleen A. Ritterbush
- Department of Geology and Geophysics, University of Utah, 115 S 1460 E, Salt Lake City, UT 84112-0102, USA
| | - Randall B. Irmis
- Department of Geology and Geophysics, University of Utah, 115 S 1460 E, Salt Lake City, UT 84112-0102, USA
- Natural History Museum of Utah, University of Utah, 301 Wakara Way, Salt Lake City, UT 84108-1214, USA
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7
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How do lizard niches conserve, diverge or converge? Further exploration of saurian evolutionary ecology. BMC Ecol Evol 2021; 21:149. [PMID: 34330210 PMCID: PMC8323276 DOI: 10.1186/s12862-021-01877-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 07/05/2021] [Indexed: 11/19/2022] Open
Abstract
Background Environmental conditions on Earth are repeated in non-random patterns that often coincide with species from different regions and time periods having consistent combinations of morphological, physiological and behavioral traits. Observation of repeated trait combinations among species confronting similar environmental conditions suggest that adaptive trait combinations are constrained by functional tradeoffs within or across niche dimensions. In an earlier study, we assembled a high-resolution database of functional traits for 134 lizard species to explore ecological diversification in relation to five fundamental niche dimensions. Here we expand and further examine multivariate relationships in that dataset to assess the relative influence of niche dimensions on the distribution of species in 6-dimensional niche space and how these may deviate from distributions generated from null models. We then analyzed a dataset with lower functional-trait resolution for 1023 lizard species that was compiled from our dataset and a published database, representing most of the extant families and environmental conditions occupied by lizards globally. Ordinations from multivariate analysis were compared with null models to assess how ecological and historical factors have resulted in the conservation, divergence or convergence of lizard niches. Results Lizard species clustered within a functional niche volume influenced mostly by functional traits associated with diet, activity, and habitat/substrate. Consistent patterns of trait combinations within and among niche dimensions yielded 24 functional groups that occupied a total niche space significantly smaller than plausible spaces projected by null models. Null model tests indicated that several functional groups are strongly constrained by phylogeny, such as nocturnality in the Gekkota and the secondarily acquired sit-and-wait foraging strategy in Iguania. Most of the widely distributed and species-rich families contained multiple functional groups thereby contributing to high incidence of niche convergence. Conclusions Comparison of empirical patterns with those generated by null models suggests that ecological filters promote limited sets of trait combinations, especially where similar conditions occur, reflecting both niche convergence and conservatism. Widespread patterns of niche convergence following ancestral niche diversification support the idea that lizard niches are defined by trait-function relationships and interactions with environment that are, to some degree, predictable and independent of phylogeny. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-021-01877-8.
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8
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Abel P, Werneburg I. Morphology of the temporal skull region in tetrapods: research history, functional explanations, and a new comprehensive classification scheme. Biol Rev Camb Philos Soc 2021; 96:2229-2257. [PMID: 34056833 DOI: 10.1111/brv.12751] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 05/12/2021] [Accepted: 05/17/2021] [Indexed: 12/21/2022]
Abstract
The morphology of the temporal region in the tetrapod skull traditionally has been a widely discussed feature of vertebrate anatomy. The evolution of different temporal openings in Amniota (mammals, birds, and reptiles), Lissamphibia (frogs, salamanders, and caecilians), and several extinct tetrapod groups has sparked debates on the phylogenetic, developmental, and functional background of this region in the tetrapod skull. This led most famously to the erection of different amniote taxa based on the number and position of temporal fenestrae in their skulls. However, most of these taxa are no longer recognised to represent natural groupings and the morphology of the temporal region is not necessarily an adequate trait for use in the reconstruction of amniote phylogenies. Yet, new fossil finds, most notably of parareptiles and stem-turtles, as well as modern embryological and biomechanical studies continue to provide new insights into the morphological diversity of the temporal region. Here, we introduce a novel comprehensive classification scheme for the various temporal morphotypes in all Tetrapoda that is independent of phylogeny and previous terminology and may facilitate morphological comparisons in future studies. We then review the history of research on the temporal region in the tetrapod skull. We document how, from the early 19th century with the first recognition of differences in the temporal region to the first proposals of phylogenetic relationships and their assessment over the centuries, the phylogenetic perspective on the temporal region has developed, and we highlight the controversies that still remain. We also compare the different functional and developmental drivers proposed for the observed morphological diversity and how the effects of internal and external factors on the structure of the tetrapod skull have been interpreted.
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Affiliation(s)
- Pascal Abel
- Senckenberg Centre for Human Evolution and Palaeoenvironment (SHEP) at Eberhard Karls Universität, Sigwartstraße 10, Tübingen, 72076, Germany.,Fachbereich Geowissenschaften der Eberhard-Karls-Universität Tübingen, Hölderlinstraße 12, Tübingen, 72074, Germany
| | - Ingmar Werneburg
- Senckenberg Centre for Human Evolution and Palaeoenvironment (SHEP) at Eberhard Karls Universität, Sigwartstraße 10, Tübingen, 72076, Germany.,Fachbereich Geowissenschaften der Eberhard-Karls-Universität Tübingen, Hölderlinstraße 12, Tübingen, 72074, Germany
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9
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Griffin CT, Stocker MR, Colleary C, Stefanic CM, Lessner EJ, Riegler M, Formoso K, Koeller K, Nesbitt SJ. Assessing ontogenetic maturity in extinct saurian reptiles. Biol Rev Camb Philos Soc 2020; 96:470-525. [PMID: 33289322 DOI: 10.1111/brv.12666] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 10/09/2020] [Accepted: 10/28/2020] [Indexed: 01/06/2023]
Abstract
Morphology forms the most fundamental level of data in vertebrate palaeontology because it is through interpretations of morphology that taxa are identified, creating the basis for broad evolutionary and palaeobiological hypotheses. Assessing maturity is one of the most basic aspects of morphological interpretation and provides the means to study the evolution of ontogenetic changes, population structure and palaeoecology, life-history strategies, and heterochrony along evolutionary lineages that would otherwise be lost to time. Saurian reptiles (the least-inclusive clade containing Lepidosauria and Archosauria) have remained an incredibly diverse, numerous, and disparate clade through their ~260-million-year history. Because of the great disparity in this group, assessing maturity of saurian reptiles is difficult, fraught with methodological and terminological ambiguity. We compiled a novel database of literature, assembling >900 individual instances of saurian maturity assessment, to examine critically how saurian maturity has been diagnosed. We review the often inexact and inconsistent terminology used in saurian maturity assessment (e.g. 'juvenile', 'mature') and provide routes for better clarity and cross-study coherence. We describe the various methods that have been used to assess maturity in every major saurian group, integrating data from both extant and extinct taxa to give a full account of the current state of the field and providing method-specific pitfalls, best practices, and fruitful directions for future research. We recommend that a new standard subsection, 'Ontogenetic Assessment', be added to the Systematic Palaeontology portions of descriptive studies to provide explicit ontogenetic diagnoses with clear criteria. Because the utility of different ontogenetic criteria is highly subclade dependent among saurians, even for widely used methods (e.g. neurocentral suture fusion), we recommend that phylogenetic context, preferably in the form of a phylogenetic bracket, be used to justify the use of a maturity assessment method. Different methods should be used in conjunction as independent lines of evidence when assessing maturity, instead of an ontogenetic diagnosis resting entirely on a single criterion, which is common in the literature. Critically, there is a need for data from extant taxa with well-represented growth series to be integrated with the fossil record to ground maturity assessments of extinct taxa in well-constrained, empirically tested methods.
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Affiliation(s)
- Christopher T Griffin
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
| | - Michelle R Stocker
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
| | - Caitlin Colleary
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Vertebrate Paleontology, Cleveland Museum of Natural History, 1 Wade Oval Drive, Cleveland, OH, 44106, U.S.A
| | - Candice M Stefanic
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Anatomical Sciences, Stony Brook University, 100 Nicolls Road, Stony Brook, NY, 11794, U.S.A
| | - Emily J Lessner
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Pathology and Anatomical Sciences, University of Missouri, 1 Hospital Drive, Columbia, MO, 65212, U.S.A
| | - Mitchell Riegler
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Geological Sciences, University of Florida, 241 Williamson Hall, Gainesville, FL, 32611, U.S.A
| | - Kiersten Formoso
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Earth Sciences, University of Southern California, 3651 Trousdale Pkwy, Los Angeles, CA, 90089, U.S.A
- Dinosaur Institute, Natural History Museum of Los Angeles County, 900 W Exposition Boulevard, Los Angeles, CA, 90007, U.S.A
| | - Krista Koeller
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
- Department of Biology, University of Florida, 220 Bartram Hall, Gainesville, FL, 32611, U.S.A
| | - Sterling J Nesbitt
- Department of Geosciences, Virginia Tech, 926 West Campus Drive, Blacksburg, VA, 24061, U.S.A
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10
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Jenkins KM, Shaw JO. Bite force data suggests relationship between acrodont tooth implantation and strong bite force. PeerJ 2020; 8:e9468. [PMID: 32656000 PMCID: PMC7333653 DOI: 10.7717/peerj.9468] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 06/11/2020] [Indexed: 12/22/2022] Open
Abstract
Extant and extinct reptiles exhibit numerous combinations of tooth implantation and attachment. Tooth implantation ranges from those possessing roots and lying within a socket (thecodonty), to teeth lying against the lingual wall of the jawbone (pleurodonty), to teeth without roots or sockets that are attached to the apex of the marginal jawbones (acrodonty). Attachment may be ligamentous (gomphosis) or via fusion (ankylosis). Generally speaking, adaptative reasonings are proposed as an underlying driver for evolutionary changes in some forms of tooth implantation and attachment. However, a substantiated adaptive hypothesis is lacking for the state of acrodont ankylosis that is seen in several lineages of Lepidosauria, a clade that is plesiomorphically pleurodont. The convergent evolution of acrodont ankylosis in several clades of lepidosaurs suggests a selective pressure shaped the evolution of the trait. We hypothesize that acrodont ankylosis as seen in Acrodonta and Sphenodon punctatus, is an adaptation either resulting from or allowing for a stronger bite force. We analyzed bite force data gathered from the literature to show that those taxa possessing acrodont dentition possess a stronger bite force on average than those taxa with pleurodont dentition. Dietary specialists with pleurodont dentition may also possess relatively high bite forces, though body size may also play a role in their ability to bite hard. Furthermore, our results have implications for the evolution of acrodont ankylosis and potential behaviors related to strong bite force that influenced the evolution of acrodonty within Acrodonta and Rhynchocephalia.
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Affiliation(s)
- Kelsey M Jenkins
- Department of Earth and Planetary Sciences, Yale University, New Haven, United States of America
| | - Jack O Shaw
- Department of Earth and Planetary Sciences, Yale University, New Haven, United States of America
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11
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Scheyer TM, Spiekman SNF, Sues HD, Ezcurra MD, Butler RJ, Jones MEH. Colobops: a juvenile rhynchocephalian reptile (Lepidosauromorpha), not a diminutive archosauromorph with an unusually strong bite. ROYAL SOCIETY OPEN SCIENCE 2020; 7:192179. [PMID: 32269817 PMCID: PMC7137947 DOI: 10.1098/rsos.192179] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 02/27/2020] [Indexed: 05/08/2023]
Abstract
Correctly identifying taxa at the root of major clades or the oldest clade-representatives is critical for meaningful interpretations of evolution. A small, partially crushed skull from the Late Triassic (Norian) of Connecticut, USA, originally described as an indeterminate rhynchocephalian saurian, was recently named Colobops noviportensis and reinterpreted as sister to all remaining Rhynchosauria, one of the earliest and globally distributed groups of herbivorous reptiles. It was also interpreted as having an exceptionally reinforced snout and powerful bite based on an especially large supratemporal fenestra. Here, after a re-analysis of the original scan data, we show that the skull was strongly dorsoventrally compressed post-mortem, with most bones out of life position. The cranial anatomy is consistent with that of other rhynchocephalian lepidosauromorphs, not rhynchosaurs. The 'reinforced snout' region and the 'exceptionally enlarged temporal region' are preservational artefacts and not exceptional among clevosaurid rhynchocephalians. Colobops is thus not a key taxon for understanding diapsid feeding apparatus evolution.
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Affiliation(s)
- Torsten M. Scheyer
- Universität Zürich, Paläontologisches Institut und Museum, Karl Schmid-Strasse 4, Zurich CH-8006, Switzerland
| | - Stephan N. F. Spiekman
- Universität Zürich, Paläontologisches Institut und Museum, Karl Schmid-Strasse 4, Zurich CH-8006, Switzerland
| | - Hans-Dieter Sues
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, MRC 121, Washington, DC 20560, USA
| | - Martín D. Ezcurra
- Sección Paleontología de Vertebrados, CONICET-Museo Argentino de Ciencias Naturales, Ángel Gallardo 470, C1405DJR, Buenos Aires, Argentina
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Richard J. Butler
- School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Marc E. H. Jones
- Research Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
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12
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Jones MEH, Pistevos JCA, Cooper N, Lappin AK, Georges A, Hutchinson MN, Holleley CE. Reproductive phenotype predicts adult bite-force performance in sex-reversed dragons (Pogona vitticeps). JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2020; 333:252-263. [PMID: 32061035 DOI: 10.1002/jez.2353] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 01/23/2020] [Accepted: 01/25/2020] [Indexed: 12/21/2022]
Abstract
Sex-related differences in morphology and behavior are well documented, but the relative contributions of genes and environment to these traits are less well understood. Species that undergo sex reversal, such as the central bearded dragon (Pogona vitticeps), offer an opportunity to better understand sexually dimorphic traits because sexual phenotypes can exist on different chromosomal backgrounds. Reproductively female dragons with a discordant sex chromosome complement (sex reversed), at least as juveniles, exhibit traits in common with males (e.g., longer tails and greater boldness). However, the impact of sex reversal on sexually dimorphic traits in adult dragons is unknown. Here, we investigate the effect of sex reversal on bite-force performance, which may be important in resource acquisition (e.g., mates and/or food). We measured body size, head size, and bite force of the three sexual phenotypes in a colony of captive animals. Among adults, we found that males (ZZm) bite more forcefully than either chromosomally concordant females (ZWf) or sex-reversed females (ZZf), and this difference is associated with having relatively larger head dimensions. Therefore, adult sex-reversed females, despite apparently exhibiting male traits as juveniles, do not develop the larger head and enhanced bite force of adult male bearded dragons. This pattern is further illustrated in the full sample by a lack of positive allometry of bite force in sex-reversed females that is observed in males. The results reveal a close association between reproductive phenotype and bite force performance, regardless of sex chromosome complement.
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Affiliation(s)
- Marc E H Jones
- Department of Cell and Developmental Biology, University College London, London, UK.,School of Biological Sciences, University of Adelaide, North Terrace, Adelaide, South Australia, Australia.,Vertebrates, South Australian Museum, North Terrace, Adelaide, South Australia, Australia
| | - Jennifer C A Pistevos
- School of Biological Sciences, University of Adelaide, North Terrace, Adelaide, South Australia, Australia.,Centre de Recherches Insulaires et Observatoire de l'Environnement CRIOBE - USR 3278: PSL Université Paris: EPHE-CNRS-UPVD, Laboratoire d'Excellence "CORAIL", Papetoai, Moorea, Polynésie Française
| | - Natalie Cooper
- Vertebrates, Department of Life Sciences, Natural History Museum, London, UK
| | | | - Arthur Georges
- Institute for Applied Ecology, Canberra, Australian Capital Territory, Australia
| | - Mark N Hutchinson
- School of Biological Sciences, University of Adelaide, North Terrace, Adelaide, South Australia, Australia.,Vertebrates, South Australian Museum, North Terrace, Adelaide, South Australia, Australia
| | - Clare E Holleley
- Institute for Applied Ecology, Canberra, Australian Capital Territory, Australia.,Australian National Wildlife Collection, National Research Collections Australia CSIRO, Canberra, Australian Capital Territory, Australia
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13
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Gray JA, Sherratt E, Hutchinson MN, Jones MEH. Evolution of cranial shape in a continental‐scale evolutionary radiation of Australian lizards. Evolution 2019; 73:2216-2229. [DOI: 10.1111/evo.13851] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 07/31/2019] [Accepted: 09/26/2019] [Indexed: 02/06/2023]
Affiliation(s)
- Jaimi A. Gray
- School of Biological Science, Thomas BuildingUniversity of Auckland Auckland 1142 New Zealand
| | - Emma Sherratt
- Department of Ecology and Evolutionary Biology, School of Biological SciencesUniversity of Adelaide North Terrace Adelaide South Australia 5005 Australia
- South Australian Museum Kintore Avenue Adelaide South Australia 5000 Australia
| | - Mark N. Hutchinson
- Department of Ecology and Evolutionary Biology, School of Biological SciencesUniversity of Adelaide North Terrace Adelaide South Australia 5005 Australia
- South Australian Museum Kintore Avenue Adelaide South Australia 5000 Australia
| | - Marc E. H. Jones
- Earth SciencesNatural History Museum London SW7 5BD United Kingdom
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14
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Jones MEH, Lucas PW, Tucker AS, Watson AP, Sertich JJW, Foster JR, Williams R, Garbe U, Bevitt JJ, Salvemini F. Neutron scanning reveals unexpected complexity in the enamel thickness of an herbivorous Jurassic reptile. J R Soc Interface 2019; 15:rsif.2018.0039. [PMID: 29899156 PMCID: PMC6030635 DOI: 10.1098/rsif.2018.0039] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 05/18/2018] [Indexed: 11/12/2022] Open
Abstract
Eilenodontines are one of the oldest radiation of herbivorous lepidosaurs (snakes, lizards and tuatara) characterized by batteries of wide teeth with thick enamel that bear mammal-like wear facets. Unlike most reptiles, eilenodontines have limited tooth replacement, making dental longevity particularly important to them. We use both X-ray and neutron computed tomography to examine a fossil tooth from the eilenodontine Eilenodon (Late Jurassic, USA). Of the two approaches, neutron tomography was more successful and facilitated measurements of enamel thickness and distribution. We find the enamel thickness to be regionally variable, thin near the cusp tip (0.10 mm) but thicker around the base (0.15–0.30 mm) and notably greater than that of other rhynchocephalians such as the extant Sphenodon (0.08–0.14 mm). The thick enamel in Eilenodon would permit greater loading, extend tooth lifespan and facilitate the establishment of wear facets that have sharp edges for orally processing plant material such as horsetails (Equisetum). The shape of the enamel dentine junction indicates that tooth development in Eilenodon and Sphenodon involved similar folding of the epithelium but different ameloblast activity.
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Affiliation(s)
- Marc E H Jones
- Department of Earth Sciences, The Natural History Museum, London, UK .,Department of Genetics and Evolution, School of Biological Sciences, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia.,South Australian Museum, North Terrace, Adelaide, South Australia 5001, Australia
| | - Peter W Lucas
- Smithsonian Tropical Research Institute, Balboa, Panama
| | - Abigail S Tucker
- Craniofacial Development and Stem Cell Biology, King's College London, London, UK
| | - Amy P Watson
- Department of Genetics and Evolution, School of Biological Sciences, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia
| | - Joseph J W Sertich
- Department of Earth Sciences, Denver Museum of Nature and Science, Denver, CO, USA
| | | | - Ruth Williams
- Department of Adelaide Microscopy, The University of Adelaide, Adelaide, South Australia 5001, Australia
| | - Ulf Garbe
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Sydney, Australia
| | - Joseph J Bevitt
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Sydney, Australia
| | - Floriana Salvemini
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Sydney, Australia
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15
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A New Clevosaurid from the Triassic (Carnian) of Brazil and the Rise of Sphenodontians in Gondwana. Sci Rep 2019; 9:11821. [PMID: 31413294 PMCID: PMC6694142 DOI: 10.1038/s41598-019-48297-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 08/02/2019] [Indexed: 12/16/2022] Open
Abstract
The early evolution of lepidosaurs is marked by an extremely scarce fossil record during the Triassic. Importantly, most Triassic lepidosaur specimens are represented by disarticulated individuals from high energy accretion deposits in Laurasia, thus greatly hampering our understanding of the initial stages of lepidosaur evolution. Here, we describe the fragmentary remains of an associated skull and mandible of Clevosaurus hadroprodon sp. nov., a new taxon of sphenodontian lepidosaur from the Late Triassic (Carnian; 237–228 Mya) of Brazil. Referral to Sphenodontia is supported by the combined presence of a marginal dentition ankylosed to the apex of the dentary, maxilla, and premaxilla; the presence of ‘secondary bone’ at the bases of the marginal dentition; and a ventrally directed mental process at the symphysis of the dentary. Our phylogenetic analyses recover Clevosaurus hadroprodon as a clevosaurid, either in a polytomy with the Late Triassic to Early Jurassic Clevosaurus and Brachyrhinodon (under Bayesian inference), or nested among different species of Clevosaurus (under maximum parsimony). Clevosaurus hadroprodon represents the oldest known sphenodontian from Gondwana, and its clevosaurid relationships indicates that these sphenodontians achieved a widespread biogeographic distribution much earlier than previously thought.
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16
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Gray JA, Hutchinson MN, Jones ME. Exceptional Disparity in Australian Agamid Lizards is a Possible Result of Arrival into Vacant Niche. Anat Rec (Hoboken) 2019; 302:1536-1543. [DOI: 10.1002/ar.24096] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Revised: 11/18/2018] [Accepted: 11/26/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Jaimi A. Gray
- School of Biological Sciences The University of Adelaide Adelaide South Australia Australia
| | - Mark N. Hutchinson
- School of Biological Sciences The University of Adelaide Adelaide South Australia Australia
- South Australian Museum Adelaide South Australia Australia
| | - Marc E.H. Jones
- School of Biological Sciences The University of Adelaide Adelaide South Australia Australia
- South Australian Museum Adelaide South Australia Australia
- Department of Earth Sciences The Natural History Museum London UK
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17
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Mongiardino Koch N, Gauthier JA. Noise and biases in genomic data may underlie radically different hypotheses for the position of Iguania within Squamata. PLoS One 2018; 13:e0202729. [PMID: 30133514 PMCID: PMC6105018 DOI: 10.1371/journal.pone.0202729] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 08/08/2018] [Indexed: 12/23/2022] Open
Abstract
Squamate reptiles are a major component of vertebrate biodiversity whose crown-clade traces its origin to a narrow window of time in the Mesozoic during which the main subclades diverged in rapid succession. Deciphering phylogenetic relationships among these lineages has proven challenging given the conflicting signals provided by genomic and phenomic data. Most notably, the placement of Iguania has routinely differed between data sources, with morphological evidence supporting a sister relationship to the remaining squamates (Scleroglossa hypothesis) and molecular data favoring a highly nested position alongside snakes and anguimorphs (Toxicofera hypothesis). We provide novel insights by generating an expanded morphological dataset and exploring the presence of phylogenetic signal, noise, and biases in molecular data. Our analyses confirm the presence of strong conflicting signals for the position of Iguania between morphological and molecular datasets. However, we also find that molecular data behave highly erratically when inferring the deepest branches of the squamate tree, a consequence of limited phylogenetic signal to resolve this ancient radiation with confidence. This, in turn, seems to result from a rate of evolution that is too high for historical signals to survive to the present. Finally, we detect significant systematic biases, with iguanians and snakes sharing faster rates of molecular evolution and a similarly biased nucleotide composition. A combination of scant phylogenetic signal, high levels of noise, and the presence of systematic biases could result in the misplacement of Iguania. We regard this explanation to be at least as plausible as the complex scenario of convergence and reversals required for morphological data to be misleading. We further evaluate and discuss the utility of morphological data to resolve ancient radiations, as well as its impact in combined-evidence phylogenomic analyses, with results relevant for the assessment of evidence and conflict across the Tree of Life.
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Affiliation(s)
- Nicolás Mongiardino Koch
- Department of Geology and Geophysics, Yale University, New Haven, Connecticut, United States of America
| | - Jacques A. Gauthier
- Department of Geology and Geophysics, Yale University, New Haven, Connecticut, United States of America
- Yale Peabody Museum of Natural History, New Haven, Connecticut, United States of America
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18
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Bever GS, Norell MA. A new rhynchocephalian (Reptilia: Lepidosauria) from the Late Jurassic of Solnhofen (Germany) and the origin of the marine Pleurosauridae. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170570. [PMID: 29291055 PMCID: PMC5717629 DOI: 10.1098/rsos.170570] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Accepted: 10/09/2017] [Indexed: 06/07/2023]
Abstract
A new rhynchocephalian is described based on a recently discovered and well-preserved specimen from the Late Jurassic (Kimmeridgian) marine limestones of Solnhofen, Bavaria. Phylogenetic analysis recovers the new taxon as the sister group to Pleurosauridae, a small radiation of rhynchocephalians representing the oldest marine invasion of crown-clade Lepidosauria. The relatively strong evidence for this taxonomically exclusive lineage, within a generally volatile rhynchocephalian tree, places the new taxon in a position to inform the early history of the pleurosaur transition to the sea. The early steps in this transition are distributed throughout the skeleton and appear to increase hydrodynamic efficiency for both swimming and aquatic feeding. This early history may also have included a global truncation of plesiomorphic ontogenetic trajectories that left a number of skeletal features with reduced levels of ossification/fusion. The exact degree to which Vadasaurus had adopted an aquatic ecology remains unclear, but the insight it provides into the origin of the enigmatic pleurosaurs exemplifies the potential of Rhynchocephalia for generating and informing broad-based questions regarding the interplay of development, morphology, ecology and macroevolutionary patterns.
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Affiliation(s)
- Gabriel S. Bever
- Center for Functional Anatomy and Evolution, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA
| | - Mark A. Norell
- Division of Paleontology, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024, USA
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19
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Geometric Morphometrics Provides an Alternative Approach for Interpreting the Affinity of Fossil Lizard Jaws. J HERPETOL 2017. [DOI: 10.1670/16-145] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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20
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21
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Whiteside DI, Duffin CJ. Late Triassic terrestrial microvertebrates from Charles Moore's ‘Microlestes’ quarry, Holwell, Somerset, UK. Zool J Linn Soc 2017. [DOI: 10.1111/zoj.12458] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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22
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Melstrom KM. The relationship between diet and tooth complexity in living dentigerous saurians. J Morphol 2017; 278:500-522. [PMID: 28145089 DOI: 10.1002/jmor.20645] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 11/28/2016] [Accepted: 12/09/2016] [Indexed: 11/07/2022]
Abstract
Living saurian reptiles exhibit a wide range of diets, from carnivores to strict herbivores. Previous research suggests that the tooth shape in some lizard clades correlates with diet, but this has not been tested using quantitative methods. I investigated the relationship between phenotypic tooth complexity and diet in living reptiles by examining the entire dentary tooth row in over 80 specimens comprising all major dentigerous saurian clades. I quantified dental complexity using orientation patch count rotated (OPCR), which discriminates diet in living and extinct mammals, where OPCR-values increase with the proportion of dietary plant matter. OPCR was calculated from high-resolution CT-scans, and I standardized OPCR-values by the total number of teeth to account for differences in tooth count across taxa. In contrast with extant mammals, there appears to be greater overlap in tooth complexity values across dietary groups because multicusped teeth characterize herbivores, omnivores, and insectivores, and because herbivorous skinks have relatively simple teeth. In particular, insectivorous lizards have dental complexities that are very similar to omnivores. Regardless, OPCR-values for animals that consume significant amounts of plant material are higher than those of carnivores, with herbivores having the highest average dental complexity. These results suggest reptilian tooth complexity is related to diet, similar to extinct and extant mammals, although phylogenetic history also plays a measurable role in dental complexity. This has implications for extinct amniotes that display a dramatic range of tooth morphologies, many with no modern analogs, which inhibits detailed dietary reconstructions. These data demonstrate that OPCR, when combined with additional morphological data, has the potential to be used to reconstruct the diet of extinct amniotes. J. Morphol. 278:500-522, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Keegan M Melstrom
- Department of Geology and Geophysics, University of Utah, 115 S 1460 E, Salt Lake City, Utah, 84112-0102
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23
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Matsumoto R, Evans SE. The palatal dentition of tetrapods and its functional significance. J Anat 2017; 230:47-65. [PMID: 27542892 PMCID: PMC5192890 DOI: 10.1111/joa.12534] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2016] [Indexed: 11/30/2022] Open
Abstract
The presence of a palatal dentition is generally considered to be the primitive condition in amniotes, with each major lineage showing a tendency toward reduction. This study highlights the variation in palatal tooth arrangements and reveals clear trends within the evolutionary history of tetrapods. Major changes occurred in the transition between early tetrapods and amphibians on the one hand, and stem amniotes on the other. These changes reflect the function of the palatal dentition, which can play an important role in holding and manipulating food during feeding. Differences in the arrangement of palatal teeth, and in their pattern of loss, likely reflect differences in feeding strategy but also changes in the arrangement of cranial soft tissues, as the palatal dentition works best with a well-developed mobile tongue. It is difficult to explain the loss of palatal teeth in terms of any single factor, but palatal tooth patterns have the potential to provide new information on diet and feeding strategy in extinct taxa.
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Affiliation(s)
- Ryoko Matsumoto
- Kanagawa Prefectural Museum Natural HistoryOdawaraKanagawaJapan
| | - Susan E. Evans
- Department of Cell and Developmental BiologyUniversity College London (UCL)LondonUK
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24
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Microanatomy and life history in Palaeopleurosaurus (Rhynchocephalia: Pleurosauridae) from the Early Jurassic of Germany. Naturwissenschaften 2016; 104:4. [PMID: 28005148 DOI: 10.1007/s00114-016-1427-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 12/05/2016] [Accepted: 12/08/2016] [Indexed: 10/20/2022]
Abstract
The tuatara (Sphenodon punctatus) from New Zealand is often-erroneously-identified as a 'living fossil', although it is the lone survivor of a large, successful radiation of Rhynchocephalia, sister taxon to squamates (lizards and snakes), that thrived through the Mesozoic and Cenozoic and experienced an intricate evolution of life histories and feeding habits. Within Rhynchocephalia, only Pleurosauridae are thought to be marine and piscivorous. Here, we present bone histological data of the Jurassic pleurosaurid Palaeopleurosaurus, showing osteosclerosis (i.e. bone mass increase) in its gastralia, and some osteosclerosis in its rib but no increase in bone mass in the femur, supporting a gradual skeletal specialization for an aquatic way of life. Similar to Sphenodon, the bone tissue deposited in Palaeopleurosaurus is lamellar zonal bone. The femoral growth pattern in Palaeopleurosaurus differs from that of terrestrial Sphenodon in a more irregular spacing of growth marks and deposition of non-annual (i.e. non-continuous) rest lines, indicating strong dependency on exogenous factors. The annual growth mark count in adult but not yet fully grown Palaeopleurosaurus is much lower when compared to adult individuals of Sphenodon, which could indicate a lower lifespan for Palaeopleurosaurus. Whereas the gastral ribs of Palaeopleurosaurus and Sphenodon are similar in composition, the ribs of Sphenodon differ profoundly in being separated into a proximal tubular rib part with a thick cortex, and an elliptical, flared ventral part characterised by extremely thin cortical bone. The latter argues against a previously inferred protective function of the ventral rib parts for the vulnerable viscera in Sphenodon.
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25
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Davis MA, Douglas MR, Collyer ML, Douglas ME. Deconstructing a Species-Complex: Geometric Morphometric and Molecular Analyses Define Species in the Western Rattlesnake (Crotalus viridis). PLoS One 2016; 11:e0146166. [PMID: 26816132 PMCID: PMC4731396 DOI: 10.1371/journal.pone.0146166] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 12/13/2015] [Indexed: 11/23/2022] Open
Abstract
Morphological data are a conduit for the recognition and description of species, and their acquisition has recently been broadened by geometric morphometric (GM) approaches that co-join the collection of digital data with exploratory 'big data' analytics. We employed this approach to dissect the Western Rattlesnake (Crotalus viridis) species-complex in North America, currently partitioned by mitochondrial (mt)DNA analyses into eastern and western lineages (two and seven subspecies, respectively). The GM data (i.e., 33 dorsal and 50 lateral head landmarks) were gleaned from 2,824 individuals located in 10 museum collections. We also downloaded and concatenated sequences for six mtDNA genes from the NCBI GenBank database. GM analyses revealed significant head shape differences attributable to size and subspecies-designation (but not their interactions). Pairwise shape distances among subspecies were significantly greater than those derived from ancestral character states via squared-change parsimony, with the greatest differences separating those most closely related. This, in turn, suggests the potential for historic character displacement as a diversifying force in the complex. All subspecies, save one, were significantly differentiated in a Bayesian discriminant function analysis (DFA), regardless of whether our priors were uniform or informative (i.e., mtDNA data). Finally, shape differences among sister-clades were significantly greater than expected by chance alone under a Brownian model of evolution, promoting the hypothesis that selection rather than drift was the driving force in the evolution of the complex. Lastly, we combine head shape and mtDNA data so as to derived an integrative taxonomy that produced robust boundaries for six OTUs (operational taxonomic units) of the C. viridis complex. We suggest these boundaries are concomitant with species-status and subsequently provide a relevant nomenclature for its recognition and representation.
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Affiliation(s)
- Mark A. Davis
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois Urbana Champaign, Champaign, IL, 61820, United States of America
| | - Marlis R. Douglas
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, 72701, United States of America
| | - Michael L. Collyer
- Department of Biology, Western Kentucky University, Bowling Green, KY, 42101, United States of America
| | - Michael E. Douglas
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, 72701, United States of America
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26
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Regnault S, Jones MEH, Pitsillides AA, Hutchinson JR. Anatomy, morphology and evolution of the patella in squamate lizards and tuatara (Sphenodon punctatus). J Anat 2016; 228:864-76. [PMID: 26740056 PMCID: PMC4831346 DOI: 10.1111/joa.12435] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2015] [Indexed: 11/29/2022] Open
Abstract
The patella (kneecap) is the largest and best-known of the sesamoid bones, postulated to confer biomechanical advantages including increasing joint leverage and reinforcing the tendon against compression. It has evolved several times independently in amniotes, but despite apparently widespread occurrence in lizards, the patella remains poorly characterised in this group and is, as yet, completely undescribed in their nearest extant relative Sphenodon (Rhynchocephalia). Through radiography, osteological and fossil studies we examined patellar presence in diverse lizard and lepidosauromorph taxa, and using computed tomography, dissection and histology we investigated in greater depth the anatomy and morphology of the patella in 16 lizard species and 19 Sphenodon specimens. We have found the first unambiguous evidence of a mineralised patella in Sphenodon, which appears similar to the patella of lizards and shares several gross and microscopic anatomical features. Although there may be a common mature morphology, the squamate patella exhibits a great deal of variability in development (whether from a cartilage anlage or not, and in the number of mineralised centres) and composition (bone, mineralised cartilage or fibrotendinous tissue). Unlike in mammals and birds, the patella in certain lizards and Sphenodon appears to be a polymorphic trait. We have also explored the evolution of the patella through ancestral state reconstruction, finding that the patella is ancestral for lizards and possibly Lepidosauria as a whole. Clear evidence of the patella in rhynchocephalian or stem lepidosaurian fossil taxa would clarify the evolutionary origin(s) of the patella, but due to the small size of this bone and the opportunity for degradation or loss we could not definitively conclude presence or absence in the fossils examined. The pattern of evolution in lepidosaurs is unclear but our data suggest that the emergence of this sesamoid may be related to the evolution of secondary ossification centres and/or changes in knee joint conformation, where enhancement of extensor muscle leverage would be more beneficial.
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Affiliation(s)
- Sophie Regnault
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, London, UK
| | - Marc E H Jones
- School of Biological Sciences, The University of Adelaide, Adelaide, SA, Australia.,South Australian Museum, Adelaide, SA, Australia
| | - Andrew A Pitsillides
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, London, UK
| | - John R Hutchinson
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, London, UK
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27
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Phylogenetics and Conservation in New Zealand: The Long and the Short of It. BIODIVERSITY CONSERVATION AND PHYLOGENETIC SYSTEMATICS 2016. [DOI: 10.1007/978-3-319-22461-9_5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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28
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Singleton M. Functional geometric morphometric analysis of masticatory system ontogeny in papionin primates. Anat Rec (Hoboken) 2015; 298:48-63. [PMID: 25338826 DOI: 10.1002/ar.23068] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 10/11/2014] [Indexed: 11/05/2022]
Abstract
The three-dimensional configuration of the primate masticatory system is constrained by the need to maximize bite forces while avoiding distraction of the temporomandibular joint (TMJ). Within these bounds, shape variation has predictable effects on functional capacities such as mechanical advantage and gape. In this study, geometric morphometric analysis is used to investigate the ontogeny of masticatory function in papionin monkeys and test the hypothesis that biomechanical constraints determine the location of molar eruption. This "constrained eruption hypothesis" predicts that the distalmost molar (DMX) will occupy a consistent location anterior to the TMJ and that jaw adductor muscles will maintain consistent positions relative to both DMX and TMJ. Craniometric landmarks were digitized on cross-sectional ontogenetic series of nine papionin species. Form-space PCA of Procrustes residuals, visualization of Bookstein shape coordinates, and nonparametric ANOVA were used to identify ontogenetic shape trends and test for significant ontogenetic changes in relative landmark positions. In most taxa, DMX maintains a consistent position relative to the TMJ while the anterior dentition migrates anteriorly. Where significant intraspecific ontogenetic differences occur, they involve anterior migration of DMX in later dental stages, likely due to late adolescent growth of the posterior palate. Attachments of the anterior temporalis and deep masseter also maintain consistent positions relative to the TMJ; however, the superficial masseter migrates anteriorly throughout ontogeny. All muscle attachments migrate laterally relative to the TMJ, reflecting positive scaling of adductor PCSA. Overall, results support the constrained eruption hypothesis and suggest mechanisms by which functional capacity is maintained during ontogeny.
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Affiliation(s)
- Michelle Singleton
- Department of Anatomy, Chicago College of Osteopathic Medicine, Midwestern University, Downers Grove, Illinois
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29
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Hsiou AS, De França MAG, Ferigolo J. New Data on the Clevosaurus (Sphenodontia: Clevosauridae) from the Upper Triassic of Southern Brazil. PLoS One 2015; 10:e0137523. [PMID: 26355294 PMCID: PMC4565693 DOI: 10.1371/journal.pone.0137523] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 08/18/2015] [Indexed: 11/18/2022] Open
Abstract
The sphenodontian fossil record in South America is well known from Mesozoic and Paleogene deposits of Argentinean Patagonia, mainly represented by opisthodontians, or taxa closely related to the modern Sphenodon. In contrast, the Brazilian fossil record is restricted to the Caturrita Formation, Late Triassic of Rio Grande do Sul, represented by several specimens of Clevosauridae, including Clevosaurus brasiliensis Bonaparte and Sues, 2006. Traditionally, Clevosauridae includes several Late Triassic to Early Jurassic taxa, such as Polysphenodon, Brachyrhinodon, and Clevosaurus, the latter well-represented by several species. The detailed description of the specimen MCN-PV 2852 allowed the first systematic revision of most Clevosaurus species. Within Clevosauridae, Polysphenodon is the most basal taxon, and an IterPCR analysis revealed Brachrhynodon as a possible Clevosaurus; C. petilus, C. wangi, and C. mcgilli as possibly distinct taxonomic entities; and the South African Clevosaurus sp. is not closely related to C. brasiliensis. These data indicate the need of a deep phylogenetic review of Clevosauridae, in order to discover synapomorphic characters among the diversity of these Triassic/Jurassic sphenodontians.
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Affiliation(s)
- Annie Schmaltz Hsiou
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | | | - Jorge Ferigolo
- Seção de Paleontologia, Museu de Ciências Naturais, Fundação Zoobotânica do Rio Grande do Sul, Porto Alegre, RS, Brazil
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30
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Romo de Vivar Martínez PR, Bento Soares M. Dentary morphological variation in Clevosaurus brasiliensis (Rhynchocephalia, Clevosauridae) from the Upper Triassic of Rio Grande do Sul, Brazil. PLoS One 2015; 10:e0119307. [PMID: 25793754 PMCID: PMC4368672 DOI: 10.1371/journal.pone.0119307] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 01/29/2015] [Indexed: 11/19/2022] Open
Abstract
Clevosaurus was a cosmopolitan rhynchocephalian genus, known from the Late Triassic to the Early Jurassic. In South America this genus is represented by C. brasiliensis, an important component of the Linha São Luiz taphocoenosis, on the top of the Norian Santa Maria 2 Sequence of Southern Brazil. The best preserved and most abundant bone elements of C. brasiliensis are dentaries, in which variations of shape and size are observed. The aim of this study is to describe and evaluate the variation, using geometric morphometrics methods. Geometric morphometric analysis of 10 specimens highlights variations in relative size of the dentary. Most of the variation observed for PC1 (83.3%) is likely related to ontogeny, and PC2 (10.0%) is likely related to taphonomic signatures. The development patterns observed, such as the growth of the dentary, consists of differential growth in length between the posterior portion of the dentary, that grows at a higher rate, regarding the anterior portion of the element. This allometric growth is similar to what is observed in other rhynchocephalians and is accompanied by the allometric skull growth, similar to the trend exhibited by clevosaurs. The taphocoenosis is bimodal (juveniles and adults) with a bias towards adult preservation. Some diagenetic influence is reflected in deformed skulls and this is observed in the tangent-plot. Finally, a strong correlation was detected between the taphonomic signatures and the PC2, regarding specially disarticulation and degree of fragmentation.
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Affiliation(s)
- Paula Rosario Romo de Vivar Martínez
- Laboratório de Paleontologia de Vertebrados, Departamento de Paleontologia e Estratigrafia, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
- * E-mail:
| | - Marina Bento Soares
- Laboratório de Paleontologia de Vertebrados, Departamento de Paleontologia e Estratigrafia, Instituto de Geociências, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
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Anderson L, Cree A, Towns D, Nelson N. Modulation of corticosterone secretion in tuatara (Sphenodon punctatus): Evidence of a dampened stress response in gravid females. Gen Comp Endocrinol 2014; 201:45-52. [PMID: 24713446 DOI: 10.1016/j.ygcen.2014.03.035] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 03/08/2014] [Accepted: 03/11/2014] [Indexed: 11/15/2022]
Abstract
Baseline and stress response glucocorticoid (GC) secretion can be modulated by individuals to support activities and physiological functions connected with reproduction (migration, mating, oviposition and/or parturition, care of young). Corticosterone (CORT) is the primary GC in reptiles and, in accordance with other vertebrates, an adrenocortical stress response is observed. Modulation of CORT secretion occurs in several reptile species, such that elevated baseline CORT concentration and/or a dampened CORT response are common during reproductive life-history events. We investigated CORT secretion after 24 h capture-restraint in the oviparous tuatara (Sphenodon punctatus), the last living rhynchocephalian, and tested whether gravid females have a dampened CORT response compared with non-gravid females. We also included males as a comparison. We confirmed that gravid females have significantly higher baseline plasma CORT concentrations than non-gravid females, suggesting increased CORT secretion during nesting. Furthermore, we found that gravid females exhibit a dampened CORT response compared to non-gravid females and males. Our results demonstrate that female reproductive condition influences CORT secretion in tuatara, and suggest that gravid females modulate CORT secretion during nesting to maintain homeostasis, effectively increasing chances of reproductive success and promoting overall fitness.
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Affiliation(s)
- Lindsay Anderson
- Allan Wilson Centre for Molecular Ecology and Evolution, School of Biological Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand.
| | - Alison Cree
- Department of Zoology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand.
| | - David Towns
- Ecosystem Development Team, Science and Technical Group, Department of Conservation, Private Bag 68-908 Newton, Auckland 1145, New Zealand.
| | - Nicola Nelson
- Allan Wilson Centre for Molecular Ecology and Evolution, School of Biological Sciences, Victoria University of Wellington, P.O. Box 600, Wellington 6140, New Zealand.
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Vermunt A, Hare KM, Besson AA. Unusual change in activity pattern at cool temperature in a reptile (Sphenodon punctatus). J Therm Biol 2014; 42:40-5. [PMID: 24802147 DOI: 10.1016/j.jtherbio.2014.02.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 01/30/2014] [Accepted: 02/28/2014] [Indexed: 11/18/2022]
Abstract
Animals that can be active both during day and night offer unique opportunities to identify factors that influence activity pattern. By experimental manipulations of temperatures under constant photoperiod, we aimed to determine if emergence, activity and thermoregulatory behaviour of juvenile tuatara (Sphenodon punctatus) varied at different temperatures (20°C, 12°C and 5°C). To help clarify its activity pattern, we compared tuatara with two lizard species endemic of the South Island of New Zealand for which activity pattern is known and clearly defined: the nocturnal common gecko Woodworthia "Otago/Southland" and the diurnal McCann׳s skink Oligosoma maccanni. Tuatara showed similar responses to both species of lizards. Similar to the diurnal skinks, tuatara emerged quickly at 20°C and 12°C while nocturnal geckos took more time to emerge. Like nocturnal geckos, tuatara continued to be active at 5°C, but only during the day. Interestingly, tuatara shifted from diurno-nocturnal activity at 20°C and 12°C to being strictly diurnal at 5°C. We suggest that this temperature-dependent strategy maximises their survival during cold periods.
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Affiliation(s)
- Aurélie Vermunt
- Biogéosciences, CNRS UMR 6282, Université de Bourgogne, 6 Bd Gabriel, 21000 Dijon, France
| | - Kelly M Hare
- Department of Zoology, University of Otago, PO Box 56, Dunedin 9054, New Zealand; Research Office, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand
| | - Anne A Besson
- Biogéosciences, CNRS UMR 6282, Université de Bourgogne, 6 Bd Gabriel, 21000 Dijon, France; Department of Zoology, University of Otago, PO Box 56, Dunedin 9054, New Zealand.
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Martínez RN, Apaldetti C, Colombi CE, Praderio A, Fernandez E, Malnis PS, Correa GA, Abelin D, Alcober O. A new sphenodontian (Lepidosauria: Rhynchocephalia) from the Late Triassic of Argentina and the early origin of the herbivore opisthodontians. Proc Biol Sci 2013; 280:20132057. [PMID: 24132307 PMCID: PMC3813332 DOI: 10.1098/rspb.2013.2057] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 09/19/2013] [Indexed: 11/12/2022] Open
Abstract
Sphenodontians were a successful group of rhynchocephalian reptiles that dominated the fossil record of Lepidosauria during the Triassic and Jurassic. Although evidence of extinction is seen at the end of the Laurasian Early Cretaceous, they appeared to remain numerically abundant in South America until the end of the period. Most of the known Late Cretaceous record in South America is composed of opisthodontians, the herbivorous branch of Sphenodontia, whose oldest members were until recently reported to be from the Kimmeridgian-Tithonian (Late Jurassic). Here, we report a new sphenodontian, Sphenotitan leyesi gen. et sp. nov., collected from the Upper Triassic Quebrada del Barro Formation of northwestern Argentina. Phylogenetic analysis identifies Sphenotitan as a basal member of Opisthodontia, extending the known record of opisthodontians and the origin of herbivory in this group by 50 Myr.
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Affiliation(s)
- Ricardo N. Martínez
- Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan, Avenida España 400 Norte, 5400 San Juan, Argentina
| | - Cecilia Apaldetti
- Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan, Avenida España 400 Norte, 5400 San Juan, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, Buenos Aires, Argentina
| | - Carina E. Colombi
- Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan, Avenida España 400 Norte, 5400 San Juan, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, Buenos Aires, Argentina
| | - Angel Praderio
- Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan, Avenida España 400 Norte, 5400 San Juan, Argentina
| | - Eliana Fernandez
- Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan, Avenida España 400 Norte, 5400 San Juan, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, Buenos Aires, Argentina
| | - Paula Santi Malnis
- Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan, Avenida España 400 Norte, 5400 San Juan, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, Buenos Aires, Argentina
| | - Gustavo A. Correa
- Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan, Avenida España 400 Norte, 5400 San Juan, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, CONICET, Buenos Aires, Argentina
| | - Diego Abelin
- Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan, Avenida España 400 Norte, 5400 San Juan, Argentina
| | - Oscar Alcober
- Instituto y Museo de Ciencias Naturales, Universidad Nacional de San Juan, Avenida España 400 Norte, 5400 San Juan, Argentina
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Jones MEH, Anderson CL, Hipsley CA, Müller J, Evans SE, Schoch RR. Integration of molecules and new fossils supports a Triassic origin for Lepidosauria (lizards, snakes, and tuatara). BMC Evol Biol 2013; 13:208. [PMID: 24063680 PMCID: PMC4016551 DOI: 10.1186/1471-2148-13-208] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Accepted: 09/02/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Lepidosauria (lizards, snakes, tuatara) is a globally distributed and ecologically important group of over 9,000 reptile species. The earliest fossil records are currently restricted to the Late Triassic and often dated to 227 million years ago (Mya). As these early records include taxa that are relatively derived in their morphology (e.g. Brachyrhinodon), an earlier unknown history of Lepidosauria is implied. However, molecular age estimates for Lepidosauria have been problematic; dates for the most recent common ancestor of all lepidosaurs range between approximately 226 and 289 Mya whereas estimates for crown-group Squamata (lizards and snakes) vary more dramatically: 179 to 294 Mya. This uncertainty restricts inferences regarding the patterns of diversification and evolution of Lepidosauria as a whole. RESULTS Here we report on a rhynchocephalian fossil from the Middle Triassic of Germany (Vellberg) that represents the oldest known record of a lepidosaur from anywhere in the world. Reliably dated to 238-240 Mya, this material is about 12 million years older than previously known lepidosaur records and is older than some but not all molecular clock estimates for the origin of lepidosaurs. Using RAG1 sequence data from 76 extant taxa and the new fossil specimens two of several calibrations, we estimate that the most recent common ancestor of Lepidosauria lived at least 242 Mya (238-249.5), and crown-group Squamata originated around 193 Mya (176-213). CONCLUSION A Early/Middle Triassic date for the origin of Lepidosauria disagrees with previous estimates deep within the Permian and suggests the group evolved as part of the faunal recovery after the end-Permain mass extinction as the climate became more humid. Our origin time for crown-group Squamata coincides with shifts towards warmer climates and dramatic changes in fauna and flora. Most major subclades within Squamata originated in the Cretaceous postdating major continental fragmentation. The Vellberg fossil locality is expected to become an important resource for providing a more balanced picture of the Triassic and for bridging gaps in the fossil record of several other major vertebrate groups.
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Affiliation(s)
- Marc EH Jones
- Research Department of Cell and Developmental Biology, Anatomy Building, UCL, University College London, Gower Street, London WCIE 6BT, UK
- School of Earth and Environmental Sciences, The University of Adelaide, North Terrace, Adelaide, South Australia 5005, Australia
| | - Cajsa Lisa Anderson
- University of Gothenburg, Department of Plant and Environmental Sciences, Gothenburg, Sweden
| | - Christy A Hipsley
- Museum für Naturkunde – Leibniz-Institut für Evolutions- und Biodiversitätsforschung an der Humboldt-Universität zu Berlin, Berlin, Germany
| | - Johannes Müller
- Museum für Naturkunde – Leibniz-Institut für Evolutions- und Biodiversitätsforschung an der Humboldt-Universität zu Berlin, Berlin, Germany
- Berlin-Brandenburg Institute of Advanced Biodiversity Research (BBIB), 14195 Berlin, Germany
| | - Susan E Evans
- Research Department of Cell and Developmental Biology, Anatomy Building, UCL, University College London, Gower Street, London WCIE 6BT, UK
| | - Rainer R Schoch
- Staatliches Museum für Naturkunde, Rosenstein 1, D-70191, Stuttgart, Germany
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Jones MEH, Anderson CL, Hipsley CA, Müller J, Evans SE, Schoch RR. Integration of molecules and new fossils supports a Triassic origin for Lepidosauria (lizards, snakes, and tuatara). BMC Evol Biol 2013. [PMID: 24063680 DOI: 10.1186/1471-2148-23-208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023] Open
Abstract
BACKGROUND Lepidosauria (lizards, snakes, tuatara) is a globally distributed and ecologically important group of over 9,000 reptile species. The earliest fossil records are currently restricted to the Late Triassic and often dated to 227 million years ago (Mya). As these early records include taxa that are relatively derived in their morphology (e.g. Brachyrhinodon), an earlier unknown history of Lepidosauria is implied. However, molecular age estimates for Lepidosauria have been problematic; dates for the most recent common ancestor of all lepidosaurs range between approximately 226 and 289 Mya whereas estimates for crown-group Squamata (lizards and snakes) vary more dramatically: 179 to 294 Mya. This uncertainty restricts inferences regarding the patterns of diversification and evolution of Lepidosauria as a whole. RESULTS Here we report on a rhynchocephalian fossil from the Middle Triassic of Germany (Vellberg) that represents the oldest known record of a lepidosaur from anywhere in the world. Reliably dated to 238-240 Mya, this material is about 12 million years older than previously known lepidosaur records and is older than some but not all molecular clock estimates for the origin of lepidosaurs. Using RAG1 sequence data from 76 extant taxa and the new fossil specimens two of several calibrations, we estimate that the most recent common ancestor of Lepidosauria lived at least 242 Mya (238-249.5), and crown-group Squamata originated around 193 Mya (176-213). CONCLUSION A Early/Middle Triassic date for the origin of Lepidosauria disagrees with previous estimates deep within the Permian and suggests the group evolved as part of the faunal recovery after the end-Permain mass extinction as the climate became more humid. Our origin time for crown-group Squamata coincides with shifts towards warmer climates and dramatic changes in fauna and flora. Most major subclades within Squamata originated in the Cretaceous postdating major continental fragmentation. The Vellberg fossil locality is expected to become an important resource for providing a more balanced picture of the Triassic and for bridging gaps in the fossil record of several other major vertebrate groups.
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Affiliation(s)
- Marc E H Jones
- Research Department of Cell and Developmental Biology, Anatomy Building, UCL, University College London, Gower Street, London WCIE 6BT, UK.
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Foth C, Rauhut OWM. The good, the bad, and the ugly: the influence of skull reconstructions and intraspecific variability in studies of cranial morphometrics in theropods and Basal saurischians. PLoS One 2013; 8:e72007. [PMID: 23951279 PMCID: PMC3738521 DOI: 10.1371/journal.pone.0072007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 07/08/2013] [Indexed: 12/03/2022] Open
Abstract
Several studies investigating macroevolutionary skull shape variation in fossil reptiles were published recently, often using skull reconstructions taken from the scientific literature. However, this approach could be potentially problematic, because skull reconstructions might differ notably due to incompleteness and/or deformation of the material. Furthermore, the influence of intraspecific variation has usually not been explored in these studies. Both points could influence the results of morphometric analyses by affecting the relative position of species to each other within the morphospace. The aim of the current study is to investigate the variation in morphometric data between skull reconstructions based on the same specimen, and to compare the results to shape variation occurring in skull reconstructions based on different specimens of the same species (intraspecific variation) and skulls of closely related species (intraspecific variation). Based on the current results, shape variation of different skull reconstructions based on the same specimen seems to have generally little influence on the results of a geometric morphometric analysis, although it cannot be excluded that some erroneous reconstructions of poorly preserved specimens might cause problems occasionally. In contrast, for different specimens of the same species the variation is generally higher than between different reconstructions based on the same specimen. For closely related species, at least with similar ecological preferences in respect to the dietary spectrum, the degree of interspecific variation can overlap with that of intraspecific variation, most probably due to similar biomechanical constraints.
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Affiliation(s)
- Christian Foth
- SNSB, Bayerische Staatssammlung für Paläontologie und Geologie, Richard-Wagner-Str. 10, Munich, Germany.
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Mello RSR, Besson AA, Hare KM, Fay V, Smith E, Cree A. Adjustment of juvenile tuatara to a cooler, southern climate: operative temperatures, emergence behaviour and growth rate. NEW ZEALAND JOURNAL OF ZOOLOGY 2013. [DOI: 10.1080/03014223.2013.775167] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- RSR Mello
- Department of Zoology, University of Otago, Dunedin, New Zealand
- Current address: HRT Oil & Gas, Manaus, Brazil
| | - AA Besson
- Department of Zoology, University of Otago, Dunedin, New Zealand
| | - KM Hare
- Department of Zoology, University of Otago, Dunedin, New Zealand
- Current address: Research Office, Victoria University of Wellington, Wellington, New Zealand
| | - V Fay
- Orokonui Ecosanctuary, Dunedin, New Zealand
| | - E Smith
- Orokonui Ecosanctuary, Dunedin, New Zealand
| | - A Cree
- Department of Zoology, University of Otago, Dunedin, New Zealand
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Jones MEH, Werneburg I, Curtis N, Penrose R, O'Higgins P, Fagan MJ, Evans SE. The head and neck anatomy of sea turtles (Cryptodira: Chelonioidea) and skull shape in Testudines. PLoS One 2012; 7:e47852. [PMID: 23144831 PMCID: PMC3492385 DOI: 10.1371/journal.pone.0047852] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 09/19/2012] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Sea turtles (Chelonoidea) are a charismatic group of marine reptiles that occupy a range of important ecological roles. However, the diversity and evolution of their feeding anatomy remain incompletely known. METHODOLOGY/PRINCIPAL FINDINGS Using computed tomography and classical comparative anatomy we describe the cranial anatomy in two sea turtles, the loggerhead (Caretta caretta) and Kemp's ridley (Lepidochelys kempii), for a better understanding of sea turtle functional anatomy and morphological variation. In both taxa the temporal region of the skull is enclosed by bone and the jaw joint structure and muscle arrangement indicate that palinal jaw movement is possible. The tongue is relatively small, and the hyoid apparatus is not as conspicuous as in some freshwater aquatic turtles. We find several similarities between the muscles of C. caretta and L. kempii, but comparison with other turtles suggests only one of these characters may be derived: connection of the m. adductor mandibulae internus into the Pars intramandibularis via the Zwischensehne. The large fleshy origin of the m. adductor mandibulae externus Pars superficialis from the jugal seems to be a characteristic feature of sea turtles. CONCLUSIONS/SIGNIFICANCE In C. caretta and L. kempii the ability to suction feed does not seem to be as well developed as that found in some freshwater aquatic turtles. Instead both have skulls suited to forceful biting. This is consistent with the observation that both taxa tend to feed on relatively slow moving but sometimes armoured prey. The broad fleshy origin of the m. adductor mandibulae externus Pars superficialis may be linked to thecheek region being almost fully enclosed in bone but the relationship is complex.
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Affiliation(s)
- Marc E H Jones
- Research Department of Cell and Developmental Biology, UCL, University College London, London, England, United Kingdom.
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Kikukawa N, Hikida T. Geometric Morphometric Analysis of Sexual Dimorphism and Allometric Growth in the Skull of the Japanese Grass Lizard,Takydromus tachydromoides(Reptilia: Lacertidae). CURRENT HERPETOLOGY 2012. [DOI: 10.5358/hsj.31.97] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Rauhut OWM, Heyng AM, López-Arbarello A, Hecker A. A new rhynchocephalian from the late jurassic of Germany with a dentition that is unique amongst tetrapods. PLoS One 2012; 7:e46839. [PMID: 23118861 PMCID: PMC3485277 DOI: 10.1371/journal.pone.0046839] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Accepted: 09/10/2012] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND Rhynchocephalians, the sister group of squamates (lizards and snakes), are only represented by the single genus Sphenodon today. This taxon is often considered to represent a very conservative lineage. However, rhynchocephalians were common during the late Triassic to latest Jurassic periods, but rapidly declined afterwards, which is generally attributed to their supposedly adaptive inferiority to squamates and/or Mesozoic mammals, which radiated at that time. New finds of Mesozoic rhynchocephalians can thus provide important new information on the evolutionary history of the group. PRINCIPLE FINDINGS A new fossil relative of Sphenodon from the latest Jurassic of southern Germany, Oenosaurus muehlheimensis gen. et sp. nov., presents a dentition that is unique amongst tetrapods. The dentition of this taxon consists of massive, continuously growing tooth plates, probably indicating a crushing dentition, thus representing a previously unknown trophic adaptation in rhynchocephalians. CONCLUSIONS/SIGNIFICANCE The evolution of the extraordinary dentition of Oenosaurus from the already highly specialized Zahnanlage generally present in derived rhynchocephalians demonstrates an unexpected evolutionary plasticity of these animals. Together with other lines of evidence, this seriously casts doubts on the assumption that rhynchocephalians are a conservative and adaptively inferior lineage. Furthermore, the new taxon underlines the high morphological and ecological diversity of rhynchocephalians in the latest Jurassic of Europe, just before the decline of this lineage on this continent. Thus, selection pressure by radiating squamates or Mesozoic mammals alone might not be sufficient to explain the demise of the clade in the Late Mesozoic, and climate change in the course of the fragmentation of the supercontinent of Pangaea might have played a major role.
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Affiliation(s)
- Oliver W M Rauhut
- Bayerische Staatssammlung für Paläontologie und Geologie and Department of Earth and Environmental Sciences, Ludwig Maximilians University, Munich, Germany.
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APESTEGUÍA SEBASTIÁN, GÓMEZ RAÚLO, ROUGIER GUILLERMOW. A basal sphenodontian (Lepidosauria) from the Jurassic of Patagonia: new insights on the phylogeny and biogeography of Gondwanan rhynchocephalians. Zool J Linn Soc 2012. [DOI: 10.1111/j.1096-3642.2012.00837.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Meloro C, Jones MEH. Tooth and cranial disparity in the fossil relatives ofSphenodon(Rhynchocephalia) dispute the persistent ‘living fossil’ label. J Evol Biol 2012; 25:2194-209. [DOI: 10.1111/j.1420-9101.2012.02595.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Revised: 07/04/2012] [Accepted: 07/09/2012] [Indexed: 11/28/2022]
Affiliation(s)
- C. Meloro
- Hull York Medical School; The University of Hull; Hull; UK
| | - M. E. H. Jones
- Research Department of Cell and Developmental Biology; University College London; London; UK
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Jones MEH, O'higgins P, Fagan MJ, Evans SE, Curtis N. Shearing mechanics and the influence of a flexible symphysis during oral food processing in Sphenodon (Lepidosauria: Rhynchocephalia). Anat Rec (Hoboken) 2012; 295:1075-91. [PMID: 22644955 DOI: 10.1002/ar.22487] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2012] [Accepted: 04/05/2012] [Indexed: 11/07/2022]
Abstract
The New Zealand tuatara, Sphenodon, has a specialized feeding system in which the teeth of the lower jaw close between two upper tooth rows before sliding forward to slice food apart like a draw cut saw. This shearing action is unique amongst living amniotes but has been compared with the chewing power stroke of mammals. We investigated details of the jaw movement using multibody dynamics analysis of an anatomically accurate three-dimensional computer model constructed from computed tomography scans. The model predicts that a flexible symphysis is necessary for changes in the intermandibular angle that permits prooral movement. Models with the greatest symphysial flexibility allow the articulation surface of the articular to follow the quadrate cotyle with the least restriction, and suggest that shearing is accompanied by a long axis rotation of the lower jaws. This promotes precise point loading between the cutting edges of particular teeth, enhancing the effectiveness of the shearing action. Given that Sphenodon is a relatively inactive reptile, we suggest that the link between oral food processing and endothermy has been overstated. Food processing improves feeding efficiency, a consideration of particular importance when food availability is unpredictable. Although this feeding mechanism is today limited to Sphenodon, a survey of fossil rhynchocephalians suggests that it was once more widespread.
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Affiliation(s)
- Marc E H Jones
- Research Department of Cell and Developmental Biology, UCL, University College London, London, UK.
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Curtis N, Jones MEH, Shi J, O'Higgins P, Evans SE, Fagan MJ. Functional relationship between skull form and feeding mechanics in Sphenodon, and implications for diapsid skull development. PLoS One 2011; 6:e29804. [PMID: 22216358 PMCID: PMC3247290 DOI: 10.1371/journal.pone.0029804] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Accepted: 12/05/2011] [Indexed: 11/19/2022] Open
Abstract
The vertebrate skull evolved to protect the brain and sense organs, but with the appearance of jaws and associated forces there was a remarkable structural diversification. This suggests that the evolution of skull form may be linked to these forces, but an important area of debate is whether bone in the skull is minimised with respect to these forces, or whether skulls are mechanically "over-designed" and constrained by phylogeny and development. Mechanical analysis of diapsid reptile skulls could shed light on this longstanding debate. Compared to those of mammals, the skulls of many extant and extinct diapsids comprise an open framework of fenestrae (window-like openings) separated by bony struts (e.g., lizards, tuatara, dinosaurs and crocodiles), a cranial form thought to be strongly linked to feeding forces. We investigated this link by utilising the powerful engineering approach of multibody dynamics analysis to predict the physiological forces acting on the skull of the diapsid reptile Sphenodon. We then ran a series of structural finite element analyses to assess the correlation between bone strain and skull form. With comprehensive loading we found that the distribution of peak von Mises strains was particularly uniform throughout the skull, although specific regions were dominated by tensile strains while others were dominated by compressive strains. Our analyses suggest that the frame-like skulls of diapsid reptiles are probably optimally formed (mechanically ideal: sufficient strength with the minimal amount of bone) with respect to functional forces; they are efficient in terms of having minimal bone volume, minimal weight, and also minimal energy demands in maintenance.
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Affiliation(s)
- Neil Curtis
- Medical and Biological Engineering Research Group, Department of Engineering, University of Hull, Hull, United Kingdom.
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Daza JD, Diogo R, Johnston P, Abdala V. Jaw Adductor Muscles across Lepidosaurs: A Reappraisal. Anat Rec (Hoboken) 2011; 294:1765-82. [DOI: 10.1002/ar.21467] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 03/26/2011] [Accepted: 06/16/2011] [Indexed: 12/28/2022]
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Feedback control from the jaw joints during biting: An investigation of the reptile Sphenodon using multibody modelling. J Biomech 2010; 43:3132-7. [DOI: 10.1016/j.jbiomech.2010.08.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 07/26/2010] [Accepted: 08/01/2010] [Indexed: 11/17/2022]
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Besson AA, Cree A. Integrating physiology into conservation: an approach to help guide translocations of a rare reptile in a warming environment. Anim Conserv 2010. [DOI: 10.1111/j.1469-1795.2010.00386.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Developmental palaeontology of Reptilia as revealed by histological studies. Semin Cell Dev Biol 2010; 21:462-70. [DOI: 10.1016/j.semcdb.2009.11.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2009] [Revised: 11/05/2009] [Accepted: 11/06/2009] [Indexed: 11/17/2022]
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WHITENACK LISAB, MOTTA PHILIPJ. Performance of shark teeth during puncture and draw: implications for the mechanics of cutting. Biol J Linn Soc Lond 2010. [DOI: 10.1111/j.1095-8312.2010.01421.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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