The turtles from the upper Eocene, Osona County (Ebro Basin, Catalonia, Spain): new material and its faunistic and environmental context

Abstract

Abstract. Eochelone voltregana n. sp. is a new marine cryptodiran cheloniid found at the Priabonian levels (latest Eocene) of the Vespella marls member of the Vic–Manlleu marls formation. It is the second cheloniid from Santa Cecília de Voltregà (Osona County, Spain), the first one being Osonachelus decorata from the same formation. Shell parameters indicate that the new species belongs to a branch of sea turtles including the Eocene Anglo–Franco–Belgian forms Argillochelys, Puppigerus and Eochelone (the shell of the latter was studied here for the first time) as well as Glarichelys from the Oligocene of Switzerland, all of them predating the worldwide living Miocene genera. The description of two other more littoral–continental Eocene species is given: Trionyx sp., from an older layer of the same formation; and the podocnemidid erymnochelyine, Cordichelys from a more basal layer of a middle Eocene (Lutetian) formation. The last one is identified as the only evidence of the Shweboemys subgroup in the European record, being distinct from the other known Osona County pleurodire Eocenochelus farresi, which is a member of the Erymnochelys group (same subfamily), from the younger Priabonian Sant Martí Xic layer. Thus, an update on the marine turtle fauna of the eastern Ebro Basin that variably opened in the east during Eocene times is provided. The turtles of Osona County belong to two suborders and five genera with three new species and extend the known distribution of their families (LSID urn:lsid:zoobank.org:act:48CE8676-7B82-4EF2-8165-27BEE90129F2).

An ancestral hard-shelled sea turtle with a mosaic of soft skin and scutes

“…This is surprising given that DK 807 has scutes on its shell, and that other previously documented hard-shelled sea turtles from the Eocene, including Eochelone , have deep sulci grooves on their skulls to suggest the presence also of facial scutes (e.g., Refs. 25 , 48 ). Thus, it is reasonable to assume that these turtles also had scales covering their flippers (in similarity with extant hard-shelled sea turtles).…”

Middle Eocene vertebrate fauna from the Aridal Formation, Sabkha of Gueran, southwestern Morocco

“…And in the robustness of the plastral elements, it is similar to E. voltregana. The Gueran species also differs from Puppigerus camperi (Gray, 1831) (Ypresian of London Clay and Lutetian of Brabant) in the lateral fontanelle size and shape, this structure being much smaller and triangular in Puppigerus Cope, 1871 adults with much wider hypoplastra, in a much wider plastron as a whole (due to the more developed shell ossification characteristic of this taxon) (Moody 1974;Lapparent de Broin et al 2018).…”

“…In these localities, the cheloniid group is represented by skulls only (Bardet et al 2017). At least it is possible to relate the cheloniid from Gueran to the taxa of the cheloniid taxa of Anglo-Franco-Belgian Basin Eocene (Ypresian-Priabonian), the ones that were previously assigned to the "Eochelyinae subfamily" (Moody 1968(Moody , 1974 and that continue their evolution in the extant cheloniids (Lapparent de Broin et al 2018).…”

“…The hypothetical pleurodiran element ought to be a possible littoral element that belongs to the Shweboemys Swinton, 1939 subgroup of Stereogenyina, known in Ad-Dakhla and Fayum (Qasr-el-Sagha) and possibly in the Lutetian of Europe and Somalia (Zouhri et al 2017;Lapparent de Broin et al 2018). It is not complete enough to be usefully compared with the poorly defined Paleogene Pelomedusoides of the Ouarzazate basin (Thanetian) at Ilimzi and Adrar Mgorn 1 in Morocco (Gheerbrant et al 2017).…”

Iberoccitanemys atlanticum (Lapparent de Broin & Murelaga, 1996) n. comb.: new data on the diversity and paleobiogeographic distributions of the Campanian-Maastrichtian bothremydid turtles of Europe

“…However, its validity was subsequently refuted (Pérez-García 2017). The strata that yielded the remains of the French taxon 'Tretosternum' ambiguum Gaudry, 1890 (from Marne, North France) have recently been re-dated (Montenat & Merle 2018;Lapparent de Broin et al 2018). As a consequence, this turtle, previously considered as Palaeocene (Broin 1977), is now recognized as an Upper Cretaceous form, from the Maastrichtian (Pérez-García 2020).…”