First record of soft-shelled turtles (Cryptodira, Trionychidae) from the Late Cretaceous of Europe

Abstract

ABSTRACT Fossil soft-shelled turtles (Trionychidae) have so far been recognized in all continents except Antarctica, based largely on remains preserving their diagnostic sculptured shell bones. The origin of the group is generally assumed to be in the Early Cretaceous of Asia, whereas they first appear in North America and Europe during the Late Cretaceous and Paleocene, respectively. Here we describe the first record of an indeterminate trionychid from the late early Campanian from southern Sweden, a part of the paleobiogeographically isolated Fenno-Scandian Shield, thus extending the stratigraphic record of the group in Europe back about 15 Ma into the Late Cretaceous. Our finding provides evidence against the currently favored dispersal scenario in which trionychid turtles are interpreted to have come to Europe first during the Paleocene either directly from North America or via Asia. The described indeterminate trionychid possibly represents a relic of a pre-Cretaceous endemic radiation of North European trionychids living mainly on the Fenno-Skandian Shield or it may indicate a potential lower latitude dispersal route of trionychids from Asia to North America via Europe during the Late Cretaceous.