Fossil and modern fiddler crabs (Uca tangeri: Ocypodidae) and their burrows from SW Spain: ichnologic and biogeographic implications

Abstract

The burrowing activity of the only European fiddler crab species, Uca tangeri (Eydoux, 1835), was studied along the shores of the estuary of the Piedra River in Lepe, southwestern Spain. Casting of burrows allowed recognition of their simple, J-shaped to irregular architecture, which displays striking similarities to fossil Pliocene burrows in the same area. The finding of body fossils ofU. tangeri in contemporaneous strata indicates these trace fossils are produced by the same species and demonstrate its presence in the eastern Atlantic coast at least for the last three million years. Burrows of U. tangeri are similar to those of other Uca spp. worldwide and also to those of other brachyurans. Their architectural simplicity makes difficult their definitive recognition in the fossil record. Nevertheless, review of existing literature confirms the presence of brachyuran burrows at least since the Cretaceous.