New insights on the only bothremydid turtle (Pleurodira) identified in the British record: Palemys bowerbankii new combination

Abstract

The British record of Pleurodira is very limited compared to that of Continental Europe. It is restricted to two lower Eocene coastal forms, corresponding to two lineages of Pelomedusoides: Podocnemididae and Bothremydidae. One of them is a recently recognized indeterminate species of the podocnemidid Eocenochelus, represented by a single individual from Bracklesham Bay (Sussex). Eocenochelus is a lineage of African origin that reached Europe during the Paleogene and is recognized in several European countries. The other British form is represented by several specimens from the London Clay of the Isle of Sheppey (Kent). Several shells were identified there, since the 19th century, allowing the description of four putative new species. The detailed study of the classic and subsequently found specimens, including unpublished individuals, confirms their attribution to a single species, for which the new combination Palemys bowerbankii is proposed. It is the only pleurodiran turtle recognized in the British record at a specific level. A neotype is designated, and a new diagnosis is provided. Photographs of most of the classic specimens of Palemys bowerbankii are included here for the first time. The detailed study of all these specimens improves the knowledge of this species. With this information, this exclusively British form is included for the first time in a cladistic analysis. It is not interpreted as the result of a Cenozoic dispersal event from Africa, as was the case with Eocenochelus, but as a member of a well-established lineage present in Europe during the Late Cretaceous, which lived in this continent at least until the early Eocene.