7 research outputs found
Multi-isotopic analysis reveals the early stem turtle Odontochelys as a nearshore herbivorous forager
IntroductionAfter decades of debate on the origin of turtles, it is now widely accepted that they are diapsid reptiles originating in the Permian from a terrestrial ancestor. It seems that the initial development of the structures that will later form the unique turtle bony shell took place as a response to a fossorial lifestyle. However, the earliest stem turtle with a fully complete plastron, Odontochelys semitestacea from the Late Triassic (lower Carnian) of China, is somewhat controversially interpreted as an aquatic or even a marine form, raising the question of the environment in which the completion of the plastron happened.MethodsHere, we analyzed the stable carbon, oxygen and sulfur isotope compositions (ÎŽ13C, ÎŽ18O and ÎŽ34S) of bones from two specimens of Odontochelys along with bones and teeth of two associated specimens of the marine ichthyosaur Guizhouichthyosaurus tangae.Results and discussionWe first show that ÎŽ18O values of Odontochelys are incompatible with a terrestrial lifestyle and imply a semi-aquatic to aquatic lifestyle. Isotopic results also demonstrate that the aquatic environment of Odontochelys was submitted to a strong marine influence, therefore excluding the possibility of a strict freshwater aquatic environment. Additionally, an unusual carbon isotope composition shows that O. semitestacea was herbivorous, probably consuming macrophytic algae in coastal zones like the extant green sea turtle (Chelonia mydas) or the marine iguana (Amblyrhynchus cristatus) do
PalĂ©obiodiversitĂ© des vertĂ©brĂ©s du LagerstĂ€tte du CrĂ©tacĂ© infĂ©rieur d'AngeacâCharente (sudâouest de la France), implications pour le renouvellement faunique continental Ă la limite J/K.
International audienceThis contribution describes the continental micro- and macrovertebrate fauna of Angeac-Charente (Berriasian, Early Cretaceous). The rich and diversified fauna indudes at least 38 different vertebrate taxa from all major clades, and is represented by more than 50 000 specimens. The Angeac-Charente locality includes the most diverse earliest Cretaceous mixed continental bonebed and the only Lager-statte known to date in the World, and it provides a good picture of a Purbeckian paleocommunity. It includes remarkable taxa such as a new ornithomimosaur, a large turiasaur, an helochelydrid turtle and numerous mammals. The vertebrate fauna of Angeac-Charente has beyond all a Purberckian character. Many exclusively European genera and species belong to families with an essentially Laurasian paleogeographic distribution. Some taxa nevertheless suggest dispersal events between Africa and Europe at the Jurassic/Cretaceous transition. The successive Charentese faunas of Chassiron (Tithonian), Cherves-de-Cognac (Berriasian) and Angeac-Charente improve our poor knowledge of the evolution of continental vertebrate faunas at the Jurassic/Cretaceous transition. Rather than reflecting an important faunal turnover between the Tithonian and the Berriasian, they record environmental changes related to the sea-level regression that characterizes the end of the Jurassic.La faune de vertébrés continentaux, représentée à la fois par des macro- et des microrestes, du Berriasien d'Angeac-Charente est décrite ici. Cette faune riche et diversifiée comprend au moins 38 taxons différents de vertébrés provenant de tous les grands clades et est constituée de plus de 50 000 spécimens. Le gisement d'Angeac-Charente est le plus diversifié des bonebeds mixtes et le seul LagerstÀtte continental du Crétacé connu à ce jour dans le monde. Il donne une bonne image de la paléocommunauté purbeckienne. Cette derniÚre comprend des taxons remarquables tels qu'un nouvel ornithomimosaure, un grand turiasaure, une tortue hélochelydride et de nombreux mammifÚres. La faune d'Angeac-Charente présente avant tout un cachet purbeckien. De nombreux genres et espÚces exclusivement européens appartiennent à des familles dont la répartition paléogéographique est essentiellement laurasiatique. Certains taxons suggÚrent néanmoins des événements de dispersion entre l'Afrique et l'Europe à la transition Jurassique/Crétacé. Les faunes charentaises des gisements de Chassiron (Tithonien), de Cherves-de-Cognac (Berriasien) et d'Angeac-Charente améliorent nos connaissances sur l'évolution des faunes continentales à la transition Jurassique-Crétacé. PlutÎt que de refléter un important renouvellement faunistique entre le Tithonien et le Berriasien, elles enregistrent les changements environnementaux liés à la régression globale qui caractérise la fin du Jurassique
Table_1_Multi-isotopic analysis reveals the early stem turtle Odontochelys as a nearshore herbivorous forager.xlsx
IntroductionAfter decades of debate on the origin of turtles, it is now widely accepted that they are diapsid reptiles originating in the Permian from a terrestrial ancestor. It seems that the initial development of the structures that will later form the unique turtle bony shell took place as a response to a fossorial lifestyle. However, the earliest stem turtle with a fully complete plastron, Odontochelys semitestacea from the Late Triassic (lower Carnian) of China, is somewhat controversially interpreted as an aquatic or even a marine form, raising the question of the environment in which the completion of the plastron happened.MethodsHere, we analyzed the stable carbon, oxygen and sulfur isotope compositions (ÎŽ13C, ÎŽ18O and ÎŽ34S) of bones from two specimens of Odontochelys along with bones and teeth of two associated specimens of the marine ichthyosaur Guizhouichthyosaurus tangae.Results and discussionWe first show that ÎŽ18O values of Odontochelys are incompatible with a terrestrial lifestyle and imply a semi-aquatic to aquatic lifestyle. Isotopic results also demonstrate that the aquatic environment of Odontochelys was submitted to a strong marine influence, therefore excluding the possibility of a strict freshwater aquatic environment. Additionally, an unusual carbon isotope composition shows that O. semitestacea was herbivorous, probably consuming macrophytic algae in coastal zones like the extant green sea turtle (Chelonia mydas) or the marine iguana (Amblyrhynchus cristatus) do.</p
Table_2_Multi-isotopic analysis reveals the early stem turtle Odontochelys as a nearshore herbivorous forager.xlsx
IntroductionAfter decades of debate on the origin of turtles, it is now widely accepted that they are diapsid reptiles originating in the Permian from a terrestrial ancestor. It seems that the initial development of the structures that will later form the unique turtle bony shell took place as a response to a fossorial lifestyle. However, the earliest stem turtle with a fully complete plastron, Odontochelys semitestacea from the Late Triassic (lower Carnian) of China, is somewhat controversially interpreted as an aquatic or even a marine form, raising the question of the environment in which the completion of the plastron happened.MethodsHere, we analyzed the stable carbon, oxygen and sulfur isotope compositions (ÎŽ13C, ÎŽ18O and ÎŽ34S) of bones from two specimens of Odontochelys along with bones and teeth of two associated specimens of the marine ichthyosaur Guizhouichthyosaurus tangae.Results and discussionWe first show that ÎŽ18O values of Odontochelys are incompatible with a terrestrial lifestyle and imply a semi-aquatic to aquatic lifestyle. Isotopic results also demonstrate that the aquatic environment of Odontochelys was submitted to a strong marine influence, therefore excluding the possibility of a strict freshwater aquatic environment. Additionally, an unusual carbon isotope composition shows that O. semitestacea was herbivorous, probably consuming macrophytic algae in coastal zones like the extant green sea turtle (Chelonia mydas) or the marine iguana (Amblyrhynchus cristatus) do.</p
PalĂ©obiodiversitĂ© des vertĂ©brĂ©s du LagerstĂ€tte du CrĂ©tacĂ© infĂ©rieur (Berriasien) dâAngeac-Charente (sud-ouest de la France), implications pour le renouvellement faunique continental Ă la limite J/K.
International audienceThis contribution describes the continental micro- and macrovertebrate fauna of Angeac-Charente (Berriasian, Early Cretaceous). The rich and diversified fauna includes at least 38 different vertebrate taxa from all major clades, and is represented by more than 50 000 specimens. The Angeac-Charente locality includes the most diverse earliest Cretaceous mixed continental bonebed and the only LagerstĂ€tte known to date in the World, and it provides a good picture of a Purbeckian paleocommunity. It includes remarkable taxa such as a new ornithomimosaur, a large turiasaur, an helochelydrid turtle and numerous mammals. The vertebrate fauna of Angeac-Charente has beyond all a Purberckian character. Many exclusively European genera and species belong to families with an essentially Laurasian paleogeographic distribution. Some taxa nevertheless suggest dispersal events between Africa and Europe at the Jurassic/Cretaceous transition. The successive Charentese faunas of Chassiron (Tithonian), Cherves-de-Cognac (Berriasian) and Angeac-Charente improve our poor knowledge of the evolution of continental vertebrate faunas at the Jurassic/Cretaceous transition. Rather than reflecting an important faunal turnover between the Tithonian and the Berriasian, they record environmental changes related to the seaâlevel regression that characterizes the end of the Jurassic.La faune de vertĂ©brĂ©s continentaux, reprĂ©sentĂ©e Ă la fois par des macro- et des microrestes, du Berriasien dâAngeac-Charente est dĂ©crite ici. Cette faune riche et diversifiĂ©e comprend au moins 38 taxons diffĂ©rents de vertĂ©brĂ©s provenant de tous les grands clades et est constituĂ©e de plus de 50 000 spĂ©cimens. Le gisement d âAngeac-Charente est le plus diversifiĂ© des bonebeds mixtes et le seul LagerstĂ€tte continental du CrĂ©tacĂ© connu Ă ce jour dans le monde. Il donne une bonne image de la palĂ©ocommunautĂ© purbeckienne. Cette derniĂšre comprend des taxons remarquables tels quâun nouvel ornithomimosaure, un grand turiasaure, une tortue hĂ©lochelydride et de nombreux mammifĂšres. La faune dâAngeac-Charente prĂ©sente avant tout un cachet purbeckien. De nombreux genres et espĂšces exclusivement europĂ©ens appartiennent Ă des familles dont la rĂ©partition palĂ©ogĂ©ographique est essentiellement laurasiatique. Certains taxons suggĂšrent nĂ©anmoins des Ă©vĂ©nements de dispersion entre lâAfrique et lâEurope Ă la transition Jurassique/CrĂ©tacĂ©. Les faunes charentaises des gisements de Chassiron (Tithonien), de Cherves-de-Cognac (Berriasien) et dâAngeac-Charente amĂ©liorent nos connaissances sur lâĂ©volution des faunes continentales Ă la transition Jurassique-CrĂ©tacĂ©. PlutĂŽt que de reflĂ©ter un important renouvellement faunistique entre le Tithonien et le Berriasien, elles enregistrent les changements environnementaux liĂ©s Ă la rĂ©gression globale qui caractĂ©rise la fin du Jurassique
Palaeontology of the Purbeck-type (Tithonian, Late Jurassic) bonebeds of Chassiron (Oléron Island, western France)
International audienceThe paralic flora and fauna from the Late Jurassic of Chassiron (Oléron Island, western France) are described. The Tithonian-aged bonebeds of Purbeck facies of this locality have yielded a rich and diverse vertebrate assemblage including fishes, amphibians, reptiles and mammals, alongside numerous plant and invertebrate remains. The Chassiron locality thus appears as a peculiar Konzentrat-LagerstÀtte in which most of the palaeoecosystem's biological components (both aquatic and terrestrial) have been preserved. The depositional environment was probably subject to salinity fluctuations, as indicated by the co-occurrence of freshwater and euryhaline organisms. This is one of the richest localities and the first mammal-bearing site known from the Jurassic of France