Criteria for recognizing marine hermit crabs in the fossil record using gastropod shells

Abstract

Hermit crabs have left a rich fossil legacy of epi- and endobionts that bored or encrusted hermit crab-inhabited shells in specific ways. Much of this rich taphonomic record, dating from the middle Jurassic, has been overlooked. Biological criteria to recognize hermitted shells in the fossil record fall within two major categories: 1) massive encrustations, such as encrusting bryozoans; and 2) subtle, thin encrustations, borings, or etchings that surround or penetrate the aperture of the shell. Massive encrustations are localized in occurrence, whereas subtle trace fossils and body fossils are common, cosmopolitan, and stratigraphically long-ranging. Important trace fossils and body fossils associated with hermit crabs are summarized here, with additional new fossil examples from the eastern Gulf Coast.Helicotaphrichnus, a unique hermit crab-associated trace fossil, is reported from the Eocene of Mississippi, extending its stratigraphic range from the Pleistocene of North America and the Miocene of Europe.