An unexpected finding: identification of the first complete shell of the Franco-Belgian middle Eocene littoral pleurodiran turtle Eocenochelus eremberti in Spain

ABSTRACT

Pleurodiran turtles are relatively abundant in the Eocene record of Europe, being mostly represented by Podocnemididae. Two genera have been identified. The most abundant and diverse is the well-known freshwater Neochelys. The other is Eocenochelus. The record of this poorly-known genus is very scarce. It is the only representative of the Upper Cretaceous to extant Erymnochelyini (i.e., a new tribe proposed here for the ‘Erymnochelys group of turtles’) interpreted as a littoral form, and the only one known outside Africa. The finding of the only complete shell of Eocenochelus hitherto identified is presented here. It comes from the Castejón de Sobrarbe-41 site, in the middle Eocene (Lutetian) of the Sobrarbe Formation of the Ainsa Basin (Huesca, Spain). The sedimentary environment of the site is compatible with its attribution to a littoral form. It is attributed to the type species of the genus, Eocenochelus eremberti, so far exclusively known by two partial shells from the middle Eocene of the Franco-Belgian Basin. Therefore, the paleobiogeographic distribution of this species is markedly increased, from the southern area of the North Sea to the Bay of Biscay. This finding provides new anatomical data on the species Eocenochelus eremberti and on its poorly known genus.

urn:lsid:zoobank.org:act:5FF64A63-3187-4752-A62E-016308877022

KEYWORDS:

• Pleurodira
• Podocnemididae
• Lutetian
• anatomy
• paleobiogeography

Acknowledgments

Authors thank N.-E. Jalil and F. de Lapparent de Broin (MNHN.F), S. Chapman (Natural History Museum, London, UK), F. Farrés (Museu Geològic del Seminari de Barcelona, Catalonia, Spain) and A. Folie and T. Smith (IRSNB) for the access to the main specimens of Eocenochelus included in the comparative studies; J. Cardiel Lalueza, the discoverer of the Castejón de Sobrarbe-41 fossil site, for his invaluable collaboration in the finding of remains of turtles and other Eocene vertebrate fossils in the Ainsa Basin; numerous colleagues from the Zaragoza University (UZ) and the Basque-Country University (UPV/EHU) involved in the excavation campaigns; and the editor G. Dyke, an anonymous reviewer and T. Smith for comments and suggestions.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research has been funded by the Ministerio de Ciencia, Innovación y Universidades (IJCI-2016-30427 and CGL2015-68363-P), the Ministerio de Economía y Competitividad (CGL2013-47521-P and CGL2017-85038-P, MINECO/FEDER, UE), the Research Groups of the Gobierno Vasco/Eusko Jaurlaritza (IT834-13 and IT1004-16), the Universidad del País Vasco/Euskal Herriko Unibertsitatea (PPG17/04 and GIU18/163), the Geoparque de Sobrarbe, and the European Regional Development Fund and the Government of Aragón (‘DGA’ and ‘Grupos de Referencia’ E18_17R). The turtle shell was prepared in the paleontological restoration workshop school promoted by the Departamento de Educación, Universidad, Cultura y Deporte of the Gobierno de Aragón (DGA) and funded by the Instituto Aragonés de Empleo (INAEM) and European Social Fund (EU).