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Szczygielski T, Marchetti L, Dróżdż D. Natural external plastron mold of the Triassic turtle Proterochersis: An unusual mode of preservation. PLoS One 2024; 19:e0299314. [PMID: 38551910 PMCID: PMC10980221 DOI: 10.1371/journal.pone.0299314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Accepted: 02/08/2024] [Indexed: 04/01/2024] Open
Abstract
Impressions of vertebrate bodies or their parts, such as trace fossils and natural molds of bones, are a valuable source of information about ancient faunas which may supplement the standard fossil record based on skeletal elements. Whereas trace fossils of animal activity are relatively common and actively studied within the field of ichnology, and natural impressions of internal or external surfaces are a frequent preservation mode in fossil invertebrates, natural molds of bones are comparatively rare and less extensively documented and discussed. Among them, internal molds (steinkerns) of turtle shells are a relatively well-known form of preservation, but the mechanisms and taphonomic prerequisites leading to their formation are poorly studied. External shell molds are even less represented in the literature. Herein, we describe a historic specimen of a natural external turtle plastron mold from the Triassic (Norian) Löwenstein Formation of Germany-a formation which also yielded a number of turtle steinkerns. The specimen is significant not only because it represents an unusual form of preservation, but also due to its remarkably large size and the presence of a potential shell pathology. Although it was initially interpreted as Proterochersis sp., the recent progress in the knowledge of proterochersid turtles leading to an increase in the number of known taxa within that group allows us to verify that assessment. We confirm that the specimen is morphologically consistent with the genus and tentatively identify it as Proterochersis robusta, the only representative of that genus from the Löwenstein Formation. We note, however, that its size exceeds the size observed thus far in Proterochersis robusta and fits within the range of Proterochersis porebensis from the Grabowa Formation of Poland. The marks interpreted as shell pathology are morphologically consistent with Karethraichnus lakkos-an ichnotaxon interpreted as a trace of ectoparasites, such as leeches. This may support the previously proposed interpretation of Proterochersis spp. as a semiaquatic turtle. Moreover, if the identification is correct, the specimen may represent a very rare case of a negative preservation of a named ichnotaxon. Finally, we discuss the taphonomy of the Löwenstein Formation turtles in comparison with other Triassic turtle-yielding formations which show no potential for the preservation of internal or external shell molds and propose a taphonomic model for the formation of such fossils.
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Affiliation(s)
| | - Lorenzo Marchetti
- Museum für Naturkunde, Leibniz-Institut für Evolutions-und Biodiversitätsforschung, Berlin, Germany
| | - Dawid Dróżdż
- Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland
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Miller E, Lee HW, Abzhanov A, Evers SW. The topological organization of the turtle cranium is constrained and conserved over long evolutionary timescales. Anat Rec (Hoboken) 2023. [PMID: 38102921 DOI: 10.1002/ar.25356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 10/30/2023] [Accepted: 11/14/2023] [Indexed: 12/17/2023]
Abstract
The cranium of turtles (Testudines) is characterized by the secondary reduction of temporal fenestrae and loss of cranial joints (i.e., characteristics of anapsid, akinetic skulls). Evolution and ontogeny of the turtle cranium are associated with shape changes. Cranial shape variation among Testudines can partially be explained by dietary and functional adaptations (neck retraction), but it is unclear if cranial topology shows similar ecomorphological signal, or if it is decoupled from shape evolution. We assess the topological arrangement of cranial bones (i.e., number, relative positioning, connections), using anatomical network analysis. Non-shelled stem turtles have similar cranial arrangements to archosauromorph outgroups. Shelled turtles (Testudinata) evolve a unique cranial organization that is associated with bone losses (e.g., supratemporal, lacrimal, ectopterygoid) and an increase in complexity (i.e., densely and highly interconnected skulls with low path lengths between bones), resulting from the closure of skull openings and establishment of unusual connections such as a parietal-pterygoid contact in the secondary braincase. Topological changes evolutionarily predate many shape changes. Topological variation and taxonomic morphospace discrimination among crown turtles are low, indicating that cranial topology may be constrained. Observed variation results from repeated losses of nonintegral bones (i.e., premaxilla, nasal, epipterygoid, quadratojugal), and changes in temporal emarginations and palate construction. We observe only minor ontogenetic changes. Topology is not influenced by diet and habitat, contrasting cranial shape. Our results indicate that turtles have a unique cranial topology among reptiles that is conserved after its initial establishment, and shows that cranial topology and shape have different evolutionary histories.
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Affiliation(s)
- Eve Miller
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Berkshire, UK
- Natural History Museum, London, UK
| | - Hiu Wai Lee
- Department of Earth Sciences, The University of Hong Kong, Hong Kong SAR, China
| | - Arkhat Abzhanov
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Berkshire, UK
- Natural History Museum, London, UK
| | - Serjoscha W Evers
- Department of Geosciences, University of Fribourg, Fribourg, Switzerland
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Augustin FJ, Rabi M, Spindler F, Kampouridis P, Hartung J, Albersdörfer R, Matzke AT. A new specimen of Solnhofia parsonsi from the Upper Jurassic (Kimmeridgian) Plattenkalk deposits of Painten (Bavaria, Germany) and comments on the relationship between limb taphonomy and habitat ecology in fossil turtles. PLoS One 2023; 18:e0287936. [PMID: 37494369 PMCID: PMC10370695 DOI: 10.1371/journal.pone.0287936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Accepted: 06/15/2023] [Indexed: 07/28/2023] Open
Abstract
The limestones of the Solnhofen area in southern Germany are one of the most important fossil Lagerstätten from the entire Mesozoic era, especially famous for the exquisitely preserved vertebrates. The turtles from the Solnhofen Limestone have been always of special interest because they include some of the best-preserved specimens from the Mesozoic. Here, we describe a new turtle specimen from the Torleite Formation (Kimmeridgian) of Painten and refer it to the thalassochelydian turtle Solnhofia parsonsi based on the presence of a unique combination of characters. The far majority of morphological differences from previously published specimens can be explained by ontogeny as the new specimen represents a larger, more ossified, and presumably older individual. Additionally, the specimen from Painten is the first described specimen of S. parsonsi preserving the largely complete and articulated limbs, the preservation of which indicates that the taxon did not possess stiffened paddles present in more pelagic marine turtles and is consistent with a previously inferred nearshore marine lifestyle. Contrary to previous inferences, we argue that taphonomic preservation of digits in articulated fossil turtles from laminated deposits cannot be used alone to infer marine or freshwater habitat. Finally, the new specimen from Painten is only the second, for which detailed information on its stratigraphic position and locality of origin are known.
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Affiliation(s)
- Felix J Augustin
- Department of Geosciences, University of Tübingen, Tübingen, Germany
| | - Márton Rabi
- Department of Geosciences, University of Tübingen, Tübingen, Germany
- Natural Sciences Collections, Martin Luther University Halle-Wittenberg, Halle, Germany
| | | | | | - Josephina Hartung
- Department of Geosciences, University of Tübingen, Tübingen, Germany
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De La Garza RG, Madsen H, Sjövall P, Osbӕck F, Zheng W, Jarenmark M, Schweitzer MH, Engdahl A, Uvdal P, Eriksson ME, Lindgren J. An ancestral hard-shelled sea turtle with a mosaic of soft skin and scutes. Sci Rep 2022; 12:22655. [PMID: 36587051 PMCID: PMC9805447 DOI: 10.1038/s41598-022-26941-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 12/22/2022] [Indexed: 01/01/2023] Open
Abstract
The transition from terrestrial to marine environments by secondarily aquatic tetrapods necessitates a suite of adaptive changes associated with life in the sea, e.g., the scaleless skin in adult individuals of the extant leatherback turtle. A partial, yet exceptionally preserved hard-shelled (Pan-Cheloniidae) sea turtle with extensive soft-tissue remains, including epidermal scutes and a virtually complete flipper outline, was recently recovered from the Eocene Fur Formation of Denmark. Examination of the fossilized limb tissue revealed an originally soft, wrinkly skin devoid of scales, together with organic residues that contain remnant eumelanin pigment and inferred epidermal transformation products. Notably, this stem cheloniid-unlike its scaly living descendants-combined scaleless limbs with a bony carapace covered in scutes. Our findings show that the adaptive transition to neritic waters by the ancestral pan-chelonioids was more complex than hitherto appreciated, and included at least one evolutionary lineage with a mosaic of integumental features not seen in any living turtle.
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Affiliation(s)
| | | | - Peter Sjövall
- grid.450998.90000 0004 0438 1242Materials and Production, RISE Research Institutes of Sweden, Borås, Sweden
| | - Frank Osbӕck
- grid.502431.10000 0004 4914 0813Museum Salling, Fur Museum, Skive, Denmark
| | - Wenxia Zheng
- grid.40803.3f0000 0001 2173 6074Department of Biological Sciences, North Carolina State University, Raleigh, NC USA
| | - Martin Jarenmark
- grid.4514.40000 0001 0930 2361Department of Geology, Lund University, Lund, Sweden
| | - Mary H. Schweitzer
- grid.4514.40000 0001 0930 2361Department of Geology, Lund University, Lund, Sweden ,grid.40803.3f0000 0001 2173 6074Department of Biological Sciences, North Carolina State University, Raleigh, NC USA ,grid.421582.80000 0001 2226 059XNorth Carolina Museum of Natural Sciences, Raleigh, NC USA
| | - Anders Engdahl
- grid.4514.40000 0001 0930 2361Medical Microspectroscopy, Biomedical Center, Lund University, Lund, Sweden
| | - Per Uvdal
- grid.4514.40000 0001 0930 2361Department of Chemistry, Lund University, Lund, Sweden
| | - Mats E. Eriksson
- grid.4514.40000 0001 0930 2361Department of Geology, Lund University, Lund, Sweden
| | - Johan Lindgren
- grid.4514.40000 0001 0930 2361Department of Geology, Lund University, Lund, Sweden
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Hermanson G, Benson RBJ, Farina BM, Ferreira GS, Langer MC, Evers SW. Cranial ecomorphology of turtles and neck retraction as a possible trigger of ecological diversification. Evolution 2022; 76:2566-2586. [PMID: 36117268 PMCID: PMC9828723 DOI: 10.1111/evo.14629] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 08/24/2022] [Accepted: 08/29/2022] [Indexed: 01/22/2023]
Abstract
Turtles have a highly modified body plan, including a rigid shell that constrains postcranial anatomy. Skull morphology and neck mobility may therefore be key to ecological specialization in turtles. However, the ecological signal of turtle skull morphologies has not been rigorously evaluated, leaving uncertainties about the roles of ecological adaptation and convergence. We evaluate turtle cranial ecomorphology using three-dimensional geometric morphometrics and phylogenetic comparative methods. Skull shape correlates with allometry, neck retraction capability, and different aquatic feeding ecologies. We find that ecological variables influence skull shape only, whereas a key functional variable (the capacity for neck retraction) influences both shape and size. Ecology and functional predictions from three-dimensional shape are validated by high success rates for extant species, outperforming previous two-dimensional approaches. We use this to infer ecological and functional traits of extinct species. Neck retraction evolved among crownward stem-turtles by the Late Jurassic, signaling functional decoupling of the skull and neck from the shell, possibly linked to a major episode of ecomorphological diversification. We also find strong evidence for convergent ecological adaptations among marine groups. This includes parallel loss of neck retraction, evidence for active hunting, possible grazing, and suction feeding in extinct marine groups. Our large-scale assessment of dietary and functional adaptation throughout turtle evolution reveals the timing and origin of their distinct ecomorphologies, and highlights the potential for ecology and function to have distinct effects on skull form.
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Affiliation(s)
- Guilherme Hermanson
- Department of GeosciencesUniversity of FribourgFribourgCH‐1700Switzerland,Department of Earth SciencesUniversity of OxfordOxfordOX1 3ANUnited Kingdom,Laboratório de Paleontologia de Ribeirão PretoUniversidade de São PauloRibeirão Preto14040‐091Brazil
| | - Roger B. J. Benson
- Department of Earth SciencesUniversity of OxfordOxfordOX1 3ANUnited Kingdom
| | - Bruna M. Farina
- Laboratório de Paleontologia de Ribeirão PretoUniversidade de São PauloRibeirão Preto14040‐091Brazil,Department of BiologyUniversity of FribourgFribourgCH‐1700Switzerland
| | - Gabriel S. Ferreira
- Senckenberg Centre for Human Evolution and Palaeoenvironment (HEP)Eberhard Karls Universität Tübingen72076TübingenGermany,Fachbereich GeowissenschaftenUniversität Tübingen72074TübingenGermany
| | - Max C. Langer
- Laboratório de Paleontologia de Ribeirão PretoUniversidade de São PauloRibeirão Preto14040‐091Brazil
| | - Serjoscha W. Evers
- Department of GeosciencesUniversity of FribourgFribourgCH‐1700Switzerland
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Johnson MM, Foffa D, Young MT, Brusatte SL. The ecological diversification and evolution of Teleosauroidea (Crocodylomorpha, Thalattosuchia), with insights into their mandibular biomechanics. Ecol Evol 2022; 12:e9484. [DOI: 10.1002/ece3.9484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 10/13/2022] [Accepted: 10/19/2022] [Indexed: 11/20/2022] Open
Affiliation(s)
| | - Davide Foffa
- Department of Geosciences Virginia Tech Blacksburg Virginia USA
- School of Geography, Earth and Environmental Sciences University of Birmingham Birmingham UK
- National Museum of Scotland Edinburgh UK
| | - Mark T. Young
- School of GeoSciences, Grant Institute University of Edinburgh Edinburgh UK
- LWL‐Museum für Naturkunde Münster Germany
| | - Stephen L. Brusatte
- National Museum of Scotland Edinburgh UK
- School of GeoSciences, Grant Institute University of Edinburgh Edinburgh UK
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