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Klug C, Spiekman SNF, Bastiaans D, Scheffold B, Scheyer TM. The marine conservation deposits of Monte San Giorgio (Switzerland, Italy): the prototype of Triassic black shale Lagerstätten. SWISS JOURNAL OF PALAEONTOLOGY 2024; 143:11. [PMID: 38450287 PMCID: PMC10912274 DOI: 10.1186/s13358-024-00308-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 01/23/2024] [Indexed: 03/08/2024]
Abstract
Marine conservation deposits ('Konservat-Lagerstätten') are characterized by their mode of fossil preservation, faunal composition and sedimentary facies. Here, we review these characteristics with respect to the famous conservation deposit of the Besano Formation (formerly Grenzbitumenzone; including the Anisian-Ladinian boundary), and the successively younger fossil-bearing units Cava inferiore, Cava superiore, Cassina beds and the Kalkschieferzone of Monte San Giorgio (Switzerland and Italy). We compare these units to a selection of important black shale-type Lagerstätten of the global Phanerozoic plus the Ediacaran in order to detect commonalities in their facies, genesis, and fossil content using principal component and hierarchical cluster analyses. Further, we put the Monte San Giorgio type Fossillagerstätten into the context of other comparable Triassic deposits worldwide based on their fossil content. The results of the principal component and cluster analyses allow a subdivision of the 45 analysed Lagerstätten into four groups, for which we suggest the use of the corresponding pioneering localities: Burgess type for the early Palaeozoic black shales, Monte San Giorgio type for the Triassic black shales, Holzmaden type for the pyrite-rich black shales and Solnhofen type for platy limestones.
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Affiliation(s)
- Christian Klug
- Universität Zürich, Paläontologisches Institut, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland
| | | | - Dylan Bastiaans
- Universität Zürich, Paläontologisches Institut, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland
| | - Beat Scheffold
- Universität Zürich, Paläontologisches Institut, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland
| | - Torsten M. Scheyer
- Universität Zürich, Paläontologisches Institut, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland
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2
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Gere K, Nagy AL, Scheyer TM, Werneburg I, Ősi A. Complex dental wear analysis reveals dietary shift in Triassic placodonts (Sauropsida, Sauropterygia). SWISS JOURNAL OF PALAEONTOLOGY 2024; 143:4. [PMID: 38328031 PMCID: PMC10844150 DOI: 10.1186/s13358-024-00304-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 01/05/2024] [Indexed: 02/09/2024]
Abstract
Placodonts were durophagous reptiles of the Triassic seas with robust skulls, jaws, and enlarged, flat, pebble-like teeth. During their evolution, they underwent gradual craniodental changes from the Early Anisian to the Rhaetian, such as a reduction in the number of teeth, an increase in the size of the posterior palatal teeth, an elongation of the premaxilla/rostrum, and a widening of the temporal region. These changes are presumably related to changes in dietary habits, which, we hypothesise, are due to changes in the type and quality of food they consumed. In the present study, the dental wear pattern of a total of nine European Middle to Late Triassic placodont species were investigated using 2D and 3D microwear analyses to demonstrate whether there could have been a dietary shift or grouping among the different species and, whether the possible changes could be correlated with environmental changes affecting their habitats. The 3D analysis shows overlap between species with high variance between values and there is no distinct separation. The 2D analysis has distinguished two main groups. The first is characterised by low number of wear features and high percentage of large pits. The other group have a high feature number, but low percentage of small pits. The 2D analysis showed a correlation between the wear data and the size of the enlarged posterior crushing teeth. Teeth with larger sizes showed less wear feature (with higher pit ratio) but larger individual features. In contrast, the dental wear facet of smaller crushing teeth shows more but smaller wear features (with higher scratch number). This observation may be related to the size of the food consumed, i.e., the wider the crown, the larger food it could crush, producing larger features. Comparison with marine mammals suggests that the dietary preference of Placochelys, Psephoderma and Paraplacodus was not exclusively hard, thick-shelled food. They may have had a more mixed diet, similar to that of modern sea otters. The diet of Henodus may have included plant food, similar to the modern herbivore marine mammals and lizards. Supplementary Information The online version contains supplementary material available at 10.1186/s13358-024-00304-x.
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Affiliation(s)
- Kinga Gere
- Institute of Geography and Earth Sciences, Department of Paleontology, ELTE Eötvös Loránd University, Pázmány Péter Sétány 1/C, 1117 Budapest, Hungary
| | - András Lajos Nagy
- Department of Propulsion Technology, Széchenyi István University, Egyetem Tér 1, 9026 Győr, Hungary
| | - Torsten M. Scheyer
- Universität Zürich, Paläontologisches Institut, Karl Schmid-Strasse 4, CH-8006 Zurich, Switzerland
| | - Ingmar Werneburg
- Senckenberg Centre for Human Evolution and Palaeoenvironment, Universität Tübingen, Sigwartstraße 10, 72076 Tübingen, Germany
- Fachbereich Geowissenschaften an der Eberhard Karls Universität Tübingen, 72074 Tübingen, Germany
| | - Attila Ősi
- Institute of Geography and Earth Sciences, Department of Paleontology, ELTE Eötvös Loránd University, Pázmány Péter Sétány 1/C, 1117 Budapest, Hungary
- Hungarian Natural History Museum, Ludovika Tér 2, 1083 Budapest, Hungary
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Lee S, Lee YN, Currie PJ, Sissons R, Park JY, Kim SH, Barsbold R, Tsogtbaatar K. A non-avian dinosaur with a streamlined body exhibits potential adaptations for swimming. Commun Biol 2022; 5:1185. [PMID: 36456823 PMCID: PMC9715538 DOI: 10.1038/s42003-022-04119-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 10/17/2022] [Indexed: 12/05/2022] Open
Abstract
Streamlining a body is a major adaptation for aquatic animals to move efficiently in the water. Whereas diving birds are well known to have streamlined bodies, such body shapes have not been documented in non-avian dinosaurs. It is primarily because most known non-avian theropods are terrestrial, barring a few exceptions. However, clear evidence of streamlined bodies is absent even in the purported semiaquatic groups. Here we report a new theropod, Natovenator polydontus gen. et sp. nov., from the Upper Cretaceous of Mongolia. The new specimen includes a well-preserved skeleton with several articulated dorsal ribs that are posterolaterally oriented to streamline the body as in diving birds. Additionally, the widely arched proximal rib shafts reflect a dorsoventrally compressed ribcage like aquatic reptiles. Its body shape suggests that Natovenator was a potentially capable swimming predator, and the streamlined body evolved independently in separate lineages of theropod dinosaurs.
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Affiliation(s)
- Sungjin Lee
- grid.31501.360000 0004 0470 5905School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
| | - Yuong-Nam Lee
- grid.31501.360000 0004 0470 5905School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
| | - Philip J. Currie
- grid.17089.370000 0001 2190 316XDepartment of Biological Sciences, University of Alberta, Edmonton, AB Canada
| | - Robin Sissons
- grid.17089.370000 0001 2190 316XDepartment of Biological Sciences, University of Alberta, Edmonton, AB Canada
| | - Jin-Young Park
- grid.31501.360000 0004 0470 5905School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
| | - Su-Hwan Kim
- grid.31501.360000 0004 0470 5905School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
| | - Rinchen Barsbold
- grid.425564.40000 0004 0587 3863Institute of Paleontology, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
| | - Khishigjav Tsogtbaatar
- grid.425564.40000 0004 0587 3863Institute of Paleontology, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia
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Klein N, Furrer H, Ehrbar I, Torres Ladeira M, Richter H, Scheyer TM. A new pachypleurosaur from the Early Ladinian Prosanto Formation in the Eastern Alps of Switzerland. SWISS JOURNAL OF PALAEONTOLOGY 2022; 141:12. [PMID: 35844249 PMCID: PMC9276568 DOI: 10.1186/s13358-022-00254-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/26/2022] [Indexed: 06/15/2023]
Abstract
UNLABELLED The Alpine Prosanto Formation (Middle Triassic) cropping out in the Ducan region in eastern Switzerland has yielded a rich fish and reptile fauna. Here, we present new pachypleurosaur remains from the upper part of the formation (Early Ladinian), similar to the previously known pachypleurosaurs from the Middle Triassic UNESCO World Heritage Site of Monte San Giorgio in southern Switzerland/northern Italy. From these remains, a new pachypleurosaur species, Prosantosaurus scheffoldi nov. gen. et spec., is described on the basis of six fairly complete skeletons, one disarticulated specimen and an isolated skull. As is typical for pachypleurosaurs and most other Triassic marine reptiles, the new taxon is based to a large degree on a combination of characters (e.g., nasals articulating broadly with the anterior margins of the prefrontals and lacking posterior processes; postorbitals with rounded anterior processes that articulate with the postfrontals anterolaterally) rather than on many unambiguous autapomorphies, although a few of the latter were found including (1) a premaxilla which is excluded from entering both the external and internal nares and (2) a parietal, which is distinctly longer than wide and carrying distinct anterolaterally angled processes. Phylogenetic relationships of the new taxon are tested within European Pachypleurosauria, revealing that the new species is the sister taxon to a clade including Serpianosaurus, Proneusticosaurus, and the monophyletic Neusticosaurus spp. Mapping of palaeogeographic and stratigraphical distribution of valid European pachypleurosaurs shows that a formerly proposed scenario of migration of pachypleurosaurs from the eastern Palaeotethys during the Olenekian into the Germanic Basin and a subsequent diversification and invasion during the Anisian into the intraplatform basins of the South Alpine realm must be re-assessed. The exceptional preservation and preparation of the Ducan fossils further allow the description of tooth replacement patterns for the first time in a European pachypleurosaur species. The "alveolarization" of replacement teeth, the horizontal replacement pattern, and the subsequent remodelling of the functional alveoli during tooth replacement supports the monophyly of Sauropterygia as discussed before. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1186/s13358-022-00254-2.
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Affiliation(s)
- Nicole Klein
- Palaeontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, CH-8006 Zurich, Switzerland
| | - Heinz Furrer
- Palaeontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, CH-8006 Zurich, Switzerland
| | - Iris Ehrbar
- Palaeontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, CH-8006 Zurich, Switzerland
| | - Marta Torres Ladeira
- Palaeontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, CH-8006 Zurich, Switzerland
| | - Henning Richter
- Diagnostic Imaging Research Unit (DIRU), Clinic for Diagnostic Imaging, Department of Clinical Diagnostics and Services, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 258c, CH-8057 Zurich, Switzerland
| | - Torsten M. Scheyer
- Palaeontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, CH-8006 Zurich, Switzerland
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5
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Klein N, Wintrich T, Hagdorn H, Spiller D, Winkelhorst H, Goris G, Scheyer TM. Placodus (Placodontia, Sauropterygia) dentaries from Winterswijk, The Netherlands (middle Anisian) and Hünfeld, Hesse, Germany (late Anisian) with comments on ontogenetic changes. PALAONTOLOGISCHE ZEITSCHRIFT 2022; 96:289-302. [PMID: 35645412 PMCID: PMC9132834 DOI: 10.1007/s12542-022-00614-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 02/17/2022] [Indexed: 06/15/2023]
Abstract
Two recently found dentaries from the Lower Muschelkalk of Winterswijk (The Netherlands) and from the Upper Muschelkalk of an outcrop in the vicinity of Hünfeld (Hesse, Germany) are studied and compared to lower jaws of placodonts. As a result, the here described specimens can be assigned to Placodus cf. gigas. However, this assignment should be regarded as preliminary due to the isolated nature of the material. More diagnostic material is necessary to validate this affiliation. A certain morphological variability in P. gigas dentaries that had been pointed out before is also obvious among the new material. Placodus gigas has a wide paleogeography and stratigraphic range and a revision of the material assigned to P. gigas with new methods is overdue but beyond the scope of the current paper. The dentary from Hünfeld is with about 4 cm preserved length the smallest so far known dentary of a Placodus. It provides interesting insights in morphological changes during ontogeny and reveals differences in trajectories when compared to dentaries of different ontogenetic stages of Cyamodus hildegardis.
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Affiliation(s)
- Nicole Klein
- Paleontological Institute and Museum, University of Zurich, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland
- Institute of Geosciences, Paleontology, University of Bonn, Nussallee 8, 53115 Bonn, Germany
| | - Tania Wintrich
- Institute of Geosciences, Paleontology, University of Bonn, Nussallee 8, 53115 Bonn, Germany
| | - Hans Hagdorn
- Muschelkalkmuseum Hagdorn, Schloßstraße 11, 74653 Ingelfingen, Germany
| | - Dave Spiller
- Dave Spiller, Liebrechtstrasse 44a, 46240 Bottrop, Germany
| | | | - Gerard Goris
- Gerard Goris, Kolmschotlanden 43, 7542 Enschede, The Netherlands
| | - Torsten M. Scheyer
- Paleontological Institute and Museum, University of Zurich, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland
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6
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Liao JL, Lan T, Xu GH, Li J, Qin YJ, Zhao MS, Li YL, Wang Y. Tooth Structure and Replacement of the Triassic Keichousaurus (Sauropterygia, Reptilia) From South China. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.741851] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The small-sized sauropterygian Keichousaurus hui was one of the most abundant marine reptiles from the Triassic Yangtze Sea in South China. Although Keichousaurus has been studied in many aspects, including the osteology, ontogeny, sexual dimorphism, and reproduction, the dentition of this marine reptile was only briefly described in external morphology. In this study, we provide new information on Keichousaurus tooth implantation, histology, and replacement based on a detailed examination of well-preserved specimens collected in the past decades. The tooth histology has been investigated for the first time by analyzing cross-sections of premaxillary teeth and the tooth attachment and implantation have been further revealed by X-ray computed microtomography. We refer the tooth replacement of Keichousaurus to the iguanid replacement type on the basis of the observed invasion of small replacement tooth into the pulp cavity of the functional tooth. Given the resemblance to other extinct and modern piscivorous predators in the morphology and structure of teeth, Keichousaurus might mainly feed on small or juvenile fishes and some relatively soft-bodied invertebrates (e.g., mysidacean shrimps) from the same ecosystem.
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7
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Pommery Y, Scheyer TM, Neenan JM, Reich T, Fernandez V, Voeten DFAE, Losko AS, Werneburg I. Dentition and feeding in Placodontia: tooth replacement in Henodus chelyops. BMC Ecol Evol 2021; 21:136. [PMID: 34225664 PMCID: PMC8256584 DOI: 10.1186/s12862-021-01835-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 05/17/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Placodontia is a Triassic sauropterygian reptile group characterized by flat and enlarged crushing teeth adapted to a durophagous diet. The enigmatic placodont Henodus chelyops has numerous autapomorphic character states, including extreme tooth count reduction to only a single pair of palatine and dentary crushing teeth. This renders the species unusual among placodonts and challenges identification of its phylogenetic position. RESULTS The skulls of two Henodus chelyops specimens were visualized with synchrotron tomography to investigate the complete anatomy of their functional and replacement crushing dentition in 3D. All teeth of both specimens were segmented, measured, and statistically compared to reveal that H. chelyops teeth are much smaller than the posterior palatine teeth of other cyamodontoid placodonts with the exception of Parahenodus atancensis from the Iberian Peninsula. The replacement teeth of this species are quite similar in size and morphology to the functional teeth. CONCLUSION As other placodonts, Henodus chelyops exhibits vertical tooth replacement. This suggests that vertical tooth replacement arose relatively early in placodont phylogeny. Analysis of dental morphology in H. chelyops revealed a concave shape of the occlusal surface and the notable absence of a central cusp. This dental morphology could have reduced dental wear and protected against failure. Hence, the concave teeth of H. chelyops appear to be adapted to process small invertebrate items, such as branchiopod crustaceans. Small gastropods were encountered in the matrix close to both studied skulls.
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Affiliation(s)
- Yannick Pommery
- Senckenberg Centre for Human Evolution and Palaeoenvironment (HEP) an der Eberhard-Karls-Universität Tübingen, Sigwartstraße 10, 72076, Tübingen, Germany.,Fachbereich Geowissenschaften, Eberhard-Karls-Universität Tübingen, Hölderlinstraße 12, 72074, Tübingen, Germany.,Université de Bourgogne-Franche-Comté, Esplanade Erasme, 21000, Dijon, France
| | - Torsten M Scheyer
- Universität Zürich, Paläontologisches Institut und Museum, Karl Schmid-Strasse 4, 8006, Zürich, Switzerland
| | - James M Neenan
- Oxford University Museum of Natural History, University of Oxford, Oxford, UK
| | - Tobias Reich
- Universität Zürich, Paläontologisches Institut und Museum, Karl Schmid-Strasse 4, 8006, Zürich, Switzerland
| | - Vincent Fernandez
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000, Grenoble, France.,The Natural History Museum, Cromwell Road, London, SW7 5BD, UK
| | - Dennis F A E Voeten
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38000, Grenoble, France.,Department of Organismal Biology, Uppsala University, Norbyvägen 18 A, 752 36, Uppsala, Sweden.,Naturalis Biodiversity Center, Darwinweg 2, 2333 CR, Leiden, the Netherlands
| | - Adrian S Losko
- Forschungs-Neutronenquelle Heinz Maier-Leibnitz, Lichtenbergstr. 1, 85748, Garching, Germany
| | - Ingmar Werneburg
- Senckenberg Centre for Human Evolution and Palaeoenvironment (HEP) an der Eberhard-Karls-Universität Tübingen, Sigwartstraße 10, 72076, Tübingen, Germany. .,Fachbereich Geowissenschaften, Eberhard-Karls-Universität Tübingen, Hölderlinstraße 12, 72074, Tübingen, Germany.
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8
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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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9
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van Casteren A, Crofts SB. The Materials of Mastication: Material Science of the Humble Tooth. Integr Comp Biol 2019; 59:1681-1689. [DOI: 10.1093/icb/icz129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Dental functional morphology, as a field, represents a confluence of materials science and biology. Modern methods in materials testing have been influential in driving the understanding of dental tissues and tooth functionality. Here we present a review of dental enamel, the outermost tissue of teeth. Enamel is the hardest biological tissue and exhibits remarkable resilience even when faced with a variety of mechanical threats. In the light of recent work, we progress the argument that the risk of mechanical degradation across multiple scales exhibits a strong and continued selection pressure on structural organization of enamel. The hierarchical nature of enamel structure presents a range of scale-dependent toughening mechanisms and provides a means by which natural selection can drive the specialization of this tissue from nanoscale reorganization to whole tooth morphology. There has been much learnt about the biomechanics of enamel recently, yet our understanding of the taxonomic diversity of this tissue is still lacking and may form an interesting avenue for future research.
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Affiliation(s)
- Adam van Casteren
- Department of Anthropology, Washington University in St Louis, Campus Box 1114, One Brookings Drive, St Louis, MO 63130, USA
| | - Stephanie B Crofts
- Department of Animal Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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10
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Clack JA, Ruta M, Milner AR, Marshall JEA, Smithson TR, Smithson KZ. Acherontiscus caledoniae: the earliest heterodont and durophagous tetrapod. ROYAL SOCIETY OPEN SCIENCE 2019; 6:182087. [PMID: 31218034 PMCID: PMC6549999 DOI: 10.1098/rsos.182087] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 04/01/2019] [Indexed: 06/09/2023]
Abstract
The enigmatic tetrapod Acherontiscus caledoniae from the Pendleian stage of the Early Carboniferous shows heterodontous and durophagous teeth, representing the earliest known examples of significant adaptations in tetrapod dental morphology. Tetrapods of the Late Devonian and Early Carboniferous (Mississippian), now known in some depth, are generally conservative in their dentition and body morphologies. Their teeth are simple and uniform, being cone-like and sometimes recurved at the tip. Modifications such as keels occur for the first time in Early Carboniferous Tournaisian tetrapods. Acherontiscus, dated as from the Pendleian stage, is notable for being very small with a skull length of about 15 mm, having an elongate vertebral column and being limbless. Cladistic analysis places it close to the Early Carboniferous adelospondyls, aïstopods and colosteids and supports the hypothesis of 'lepospondyl' polyphyly. Heterodonty is associated with a varied diet in tetrapods, while durophagy suggests a diet that includes hard tissue such as chitin or shells. The mid-Carboniferous saw a significant increase in morphological innovation among tetrapods, with an expanded diversity of body forms, skull shapes and dentitions appearing for the first time.
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Affiliation(s)
| | - Marcello Ruta
- School of Life Sciences, University of Lincoln, Joseph Banks Laboratories, Green Lane, Lincoln LN6 7DL, UK
| | - Andrew R. Milner
- Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW7 5BD, UK
| | - John E. A. Marshall
- School of Ocean and Earth Science, National Oceanography Centre, University of Southampton, Waterfront Campus, European Way, Southampton SO14 3ZH, UK
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11
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Wang W, Li C, Wu XC. An adult specimen of Sinocyamodus xinpuensis (Sauropterygia: Placodontia) from Guanling, Guizhou, China. Zool J Linn Soc 2018. [DOI: 10.1093/zoolinnean/zly080] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Wei Wang
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
- Universität Zürich, Paläontologisches Institut und Museum, Zürich, Switzerland
| | - Chun Li
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing, China
| | - Xiao-Chun Wu
- Canadian Museum of Nature, Station D, Ottawa, Ontario, Canada
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12
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Hanai T, Tsuihiji T. Description of Tooth Ontogeny and Replacement Patterns in a Juvenile Tarbosaurus bataar (Dinosauria: Theropoda) Using CT-Scan Data. Anat Rec (Hoboken) 2018; 302:1210-1225. [PMID: 30378771 DOI: 10.1002/ar.24014] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 07/16/2018] [Accepted: 08/01/2018] [Indexed: 11/08/2022]
Abstract
Teeth are continually replaced in most of non-mammalian gnathostomes to maintain their functional dentitions. To clarify the tooth replacement patterns in tyrannosaurid theropod dinosaurs, we examined well-preserved dentitions (both premaxillae, left maxilla, partial right maxilla, and both dentaries) of a juvenile Tarbosaurus bataar (MPC-D 107/7) using X-ray computed tomographic (CT) imaging. Three-dimensional (3D) rendering of the dentitions and staging of replacement teeth allowed quantitative analyses of the tooth ontogeny and replacement patterns in this specimen. These strategies were validated by comparing the results between MPC-D 107/7 and extant crocodilians, which are taxa that have previously been studied using non-CT methods. 3D-rendered dentitions of MPC-D 107/7 showed alternate replacement patterns between odd- and even-numbered alveoli. Such patterns were discontinuous at the premaxilla-maxilla junctions, suggesting the division of replacement patterns between the two dentitions possessing morpho-functionally different features. The replacement process in the odd-numbered alveoli of the left maxilla sequentially proceeded from distal alveoli. Meanwhile, in the both dentaries, there were simple alternate patterns in which functional teeth would be simultaneously shed out in every second alveoli. Such a simple alternation had never been reported in the adult tyrannosaurid dentaries. Under this pattern, the half of functional teeth in a single dentition would be shed at the same time, which may hamper foraging functions. We conclude that the simple alternate patterns found in the dentary dentitions of MPC-D 107/7 represent transient condition in juvenile tyrannosaurids, suggesting ontogenetic changes in tooth replacement patterns in the tyrannosaurid dentary. Anat Rec, 302:1210-1225, 2019. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Tomoya Hanai
- Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan
| | - Takanobu Tsuihiji
- Department of Earth and Planetary Science, The University of Tokyo, Tokyo, Japan
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Simões TR, Caldwell MW, Tałanda M, Bernardi M, Palci A, Vernygora O, Bernardini F, Mancini L, Nydam RL. X-ray computed microtomography of Megachirella wachtleri. Sci Data 2018; 5:180244. [PMID: 30398474 PMCID: PMC6219415 DOI: 10.1038/sdata.2018.244] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 09/19/2018] [Indexed: 11/09/2022] Open
Abstract
Understanding the origin and early evolution of squamates has been a considerable challenge given the extremely scarce fossil record of early squamates and their poor degree of preservation. In order to overcome those limitations, we conducted high-resolution X-ray computed tomography (CT) studies on the fossil reptile Megachirella wachtleri (Middle Triassic, northern Italy), which revealed an important set of features indicating this is the oldest known fossil squamate in the world, predating the previous oldest record by ca. 75 million years. We also compiled a new phylogenetic data set comprising a large sample of diapsid reptiles (including morphological and molecular data) to investigate the phylogenetic relationships of early squamates and other reptile groups along with the divergence time of those lineages. The re-description of Megachirella and a new phylogenetic hypothesis of diapsid relationships are presented in a separate study. Here we present the data descriptors for the tomographic scans of Megachirella, which holds fundamental information to our understanding on the early evolution of one of the largest vertebrate groups on Earth today.
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Affiliation(s)
- Tiago R Simões
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Michael W Caldwell
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.,Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Mateusz Tałanda
- Department of Palaeobiology and Evolution, Faculty of Biology, University of Warsaw, Żwirki we Wigury 101, 02-089 Warsaw, Poland
| | - Massimo Bernardi
- MUSE - Museo delle Scienze di Trento, Corso del Lavoro e della Scienza 3, Trento, 38123 Italy.,School of Earth Sciences, University of Bristol, Bristol, BS81RJ, UK
| | - Alessandro Palci
- College of Science and Engineering, Flinders University, Adelaide, South Australia 5042, Australia.,South Australian Museum, North Terrace, Adelaide, South Australia 5000, Australia
| | - Oksana Vernygora
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada
| | - Federico Bernardini
- Museo Storico della Fisica e Centro di Studi e Ricerche "Enrico Fermi", Piazza del Viminale 1, 00184 Roma, Italy.,The "Abdus Salam" International Centre for Theoretical Physics, Strada Costiera 11, Trieste, 34151 Italy
| | - Lucia Mancini
- Elettra - Sincrotrone Trieste S.C.p.A., SS 14, Km 163.5, Area Science Park, Basovizza, 34149 Trieste, Italy
| | - Randall L Nydam
- Department of Anatomy, Arizona College of Osteopathic Medicine, Midwestern University, 19555N. 59th Dr., Glendale, AZ 85383, USA
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14
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He Y, Makovicky PJ, Xu X, You H. High-resolution computed tomographic analysis of tooth replacement pattern of the basal neoceratopsian Liaoceratops yanzigouensis informs ceratopsian dental evolution. Sci Rep 2018; 8:5870. [PMID: 29651146 PMCID: PMC5897341 DOI: 10.1038/s41598-018-24283-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Accepted: 03/29/2018] [Indexed: 11/09/2022] Open
Abstract
The dental morphology and tooth replacement pattern of Liaoceratops yanzigouensis, the earliest known neoceratopsian, are important for our understanding of the evolution of the ceratopsian dental system. Here we describe the dental morphology and tooth replacement of Liaoceratops yanzigouensis based on high-resolution computed tomographic (CT) scan data of three specimens including the holotype, the first study for basal ceratopsian. The three-dimensional reconstructions reveal some important new information, including: three teeth in the premaxilla in one side, two more teeth in the dentary than in the maxilla, incipiently developed mesial grooves on some crowns, two generations of replacement teeth within some tooth families; and most functional teeth were under heavy resorption by the replacement process, but still remained functional. Comparisons of tooth pair positions from opposite sides in the four jaw quadrants of three specimens revealed a degree of bilateral symmetry in replacement pattern. Reconstruction of Zahnreihen yields an avergae z-spacing of 2.58 with simultaneous front-to-back tooth replacement. Our study presents the earliest evidence of derived neoceratopsian traits of the complex dental batteries in ceratopsids. Most significantly, our models reveal the tracts of partially resorbed functional teeth which appears to track the growth of the jaws, traits previously undocumented in Ceratopsia.
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Affiliation(s)
- Yiming He
- School of Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu, 210046, China.
| | - Peter J Makovicky
- Department of Geology, The Field Museum, Chicago, llinois, 60640, United States of America
| | - Xing Xu
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Palaeontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100046, China
| | - Hailu You
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Palaeontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, 100046, China
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15
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Exceptionally prolonged tooth formation in elasmosaurid plesiosaurians. PLoS One 2017; 12:e0172759. [PMID: 28241059 PMCID: PMC5328283 DOI: 10.1371/journal.pone.0172759] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 02/09/2017] [Indexed: 11/19/2022] Open
Abstract
Elasmosaurid plesiosaurians were globally prolific marine reptiles that dominated the Mesozoic seas for over 70 million years. Their iconic body-plan incorporated an exceedingly long neck and small skull equipped with prominent intermeshing ‘fangs’. How this bizarre dental apparatus was employed in feeding is uncertain, but fossilized gut contents indicate a diverse diet of small pelagic vertebrates, cephalopods and epifaunal benthos. Here we report the first plesiosaurian tooth formation rates as a mechanism for servicing the functional dentition. Multiple dentine thin sections were taken through isolated elasmosaurid teeth from the Upper Cretaceous of Sweden. These specimens revealed an average of 950 daily incremental lines of von Ebner, and infer a remarkably protracted tooth formation cycle of about 2–3 years–other polyphyodont amniotes normally take ~1–2 years to form their teeth. Such delayed odontogenesis might reflect differences in crown length and function within an originally uneven tooth array. Indeed, slower replacement periodicity has been found to distinguish larger caniniform teeth in macrophagous pliosaurid plesiosaurians. However, the archetypal sauropterygian dental replacement system likely also imposed constraints via segregation of the developing tooth germs within discrete bony crypts; these partly resorbed to allow maturation of the replacement teeth within the primary alveoli after displacement of the functional crowns. Prolonged dental formation has otherwise been linked to tooth robustness and adaption for vigorous food processing. Conversely, elasmosaurids possessed narrow crowns with an elongate profile that denotes structural fragility. Their apparent predilection for easily subdued prey could thus have minimized this potential for damage, and was perhaps coupled with selective feeding strategies that ecologically optimized elasmosaurids towards more delicate middle trophic level aquatic predation.
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16
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Sassoon J, Foffa D, Marek R. Dental ontogeny and replacement in Pliosauridae. ROYAL SOCIETY OPEN SCIENCE 2015; 2:150384. [PMID: 26715998 PMCID: PMC4680613 DOI: 10.1098/rsos.150384] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Accepted: 10/08/2015] [Indexed: 06/05/2023]
Abstract
Dental morphology and patterns of tooth replacement in representatives of the clade Pliosauridae (Reptilia, Sauropterygia) are evaluated in detail. The jaws of one basal (Thalassiodracon hawkinsii) and two derived species (Pliosaurus carpenteri, Pliosaurus kevani) were visualized by μCT scans, and the ontogenetic patterns, or 'movement paths', of replacement teeth could be mapped. Other specimens (Peloneustes philarchus and Pliosaurus westbuyensis) with well-preserved jaws containing functional and replacement teeth in situ were also examined directly, and waves of tooth replacement could be inferred from the degree of in situ tooth development and the fusion between functional and replacement alveoli. The analysis revealed symmetrical tooth eruption over the medial axis throughout the length of the jaw in the basal pliosaurid Thalassiodracon. By contrast, symmetrical tooth eruption patterns occur only along the anterior sections of the jaws of derived pliosaurids. In Pliosaurus, replacement schedules differ in the anterior and posterior portions of the jaws and appear to correlate with differences in tooth morphology and symmetrical replacement. The anterior teeth exhibit longer replacement cycle periods and symmetrical replacement, while shorter cycle periods and asymmetry are seen posteriorly. A longer period suggests slower replacement and is characteristic of large, specialized caniniform teeth in the longer snouted Late Jurassic taxa. Smaller posterior teeth have a shorter period and therefore a faster replacement cycle. The transition from long to short replacement period over the length of the jaw is thought to account for the loss of symmetry. This differentiation could relate to differential tooth function and a type of heterodonty. We therefore propose a new model of pliosaurid tooth replacement patterns and present it in a phylogenetic context.
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Affiliation(s)
- Judyth Sassoon
- School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen’s Road, Bristol BS8 1RJ, UK
| | - Davide Foffa
- School of GeoSciences, Grant Institute, University of Edinburgh, The King’s Buildings, James Hutton Road, Edinburgh EH9 3FE, UK
| | - Ryan Marek
- Department of Musculoskeletal Biology, University of Liverpool, Duncan Building, Daulby Street, Liverpool L69 3GE, UK
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Klein N, Neenan JM, Scheyer TM, Griebeler EM. Growth patterns and life-history strategies in Placodontia (Diapsida: Sauropterygia). ROYAL SOCIETY OPEN SCIENCE 2015; 2:140440. [PMID: 26587259 PMCID: PMC4632572 DOI: 10.1098/rsos.140440] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 06/11/2015] [Indexed: 06/05/2023]
Abstract
Placodontia is a clade of durophagous, near shore marine reptiles from Triassic sediments of modern-day Europe, Middle East and China. Although much is known about their primary anatomy and palaeoecology, relatively little has been published regarding their life history, i.e. ageing, maturation and growth. Here, growth records derived from long bone histological data of placodont individuals are described and modelled to assess placodont growth and life-history strategies. Growth modelling methods are used to confirm traits documented in the growth record (age at onset of sexual maturity, age when asymptotic length was achieved, age at death, maximum longevity) and also to estimate undocumented traits. Based on these growth models, generalized estimates of these traits are established for each taxon. Overall differences in bone tissue types and resulting growth curves indicate different growth patterns and life-history strategies between different taxa of Placodontia. Psephoderma and Paraplacodus grew with lamellar-zonal bone tissue type and show growth patterns as seen in modern reptiles. Placodontia indet. aff. Cyamodus and some Placodontia indet. show a unique combination of fibrolamellar bone tissue regularly stratified by growth marks, a pattern absent in modern sauropsids. The bone tissue type of Placodontia indet. aff. Cyamodus and Placodontia indet. indicates a significantly increased basal metabolic rate when compared with modern reptiles. Double lines of arrested growth, non-annual rest lines in annuli, and subcycles that stratify zones suggest high dependence of placodont growth on endogenous and exogenous factors. Histological and modelled differences within taxa point to high individual developmental plasticity but sexual dimorphism in growth patterns and the presence of different taxa in the sample cannot be ruled out.
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Affiliation(s)
- Nicole Klein
- State Museum of Natural History Stuttgart, Rosenstein 1, 70191 Stuttgart, Germany
| | - James M. Neenan
- Palaeontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, 8006 Zürich, Switzerland
| | - Torsten M. Scheyer
- Palaeontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, 8006 Zürich, Switzerland
| | - Eva Maria Griebeler
- Department of Ecology, Zoological Institute, University of Mainz, 55099 Mainz, Germany
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18
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Neenan JM, Li C, Rieppel O, Scheyer TM. The cranial anatomy of Chinese placodonts and the phylogeny of Placodontia (Diapsida: Sauropterygia). Zool J Linn Soc 2015. [DOI: 10.1111/zoj.12277] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- James M. Neenan
- Palaeontological Institute and Museum; University of Zurich; Karl Schmid-Strasse 4 8006 Zurich Switzerland
- The Function, Evolution and Anatomy Research (FEAR) Lab; School of Environmental and Rural Science; University of New England; Armidale NSW 2351 Australia
| | - Chun Li
- Institute of Vertebrate Paleontology and Paleoanthropology; Chinese Academy of Sciences; Beijing 100044 China
| | - Olivier Rieppel
- The Field Museum; 1400 South Lake Shore Drive Chicago IL 60605-2496 USA
| | - Torsten M. Scheyer
- Palaeontological Institute and Museum; University of Zurich; Karl Schmid-Strasse 4 8006 Zurich Switzerland
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19
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Crofts S. Finite element modeling of occlusal variation in durophagous tooth systems. J Exp Biol 2015; 218:2705-11. [DOI: 10.1242/jeb.120097] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 06/22/2015] [Indexed: 12/17/2022]
Abstract
In addition to breaking hard prey items, the teeth of durophagous predators must also resist failure under high loads. To understand the effects of morphology on tooth resistance to failure, finite element models were used to examine differences in total strain energy (J), first principal strain, and the distribution of strains in a diversity of canonical durophagous tooth morphologies. By changing the way loads were applied to the models, I was also able to model the effects of large and small prey items. Tooth models with overall convex morphologies have higher in-model strains than those with flat or concave occlusal surface. When a cusp is added to the tooth model, taller or thinner cusps increase in-model strain. While there is little difference in the relationships between tooth morphology and strain measurements for most models, there is a marked difference between effects of the large and small prey loads on the concave and flat tooth morphologies. Comparing these data with measurements of force required by these same morphologies to break prey items illustrates functional tradeoffs between the need to prevent tooth failure under high loads by minimizing in-tooth strain versus the drive to reduce the total applied force.
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Affiliation(s)
- Stephanie Crofts
- Department of Biology, University of Washington, Seattle, WA 98195-1800, USA
- University of Washington, Friday Harbor Laboratories, 620 University Rd., Friday Harbor WA 98250, USA
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