Isolated mantis shrimp dactyli from the Pliocene of North Carolina and their bearing on the history of Stomatopoda

摘要

We describe 54 fragmentary specimens from the Pliocene of North Carolina that represent isolated dactyli of mantis shrimps. These specimens are preserved uncompressed within three dimensions in calcium phosphate. The dactyli have an estimated maximum length of 15 millimeters and bear six spines. The specimens appear to be hollow and preserve fine details, especially a narrow crest on the dorsal side of the spines, a functional blade edge that has not been previously found on any fossil stomatopod. The specimens are provisionally attributed to the species Squilla empusa, found nowadays along the entire East coast of the United States of America. Fossil occurrences are known from the Pleistocene of Maryland and from the late Pleistocene or early Holocene of Connecticut. Though isolated dactyli are less informative on the taxonomic level, they can be important on the paleo-ecological level, positively demonstrating the presence of ambush predators in an investigated paleo-community. Given the scarce stomatopod fossil record and the exceptional three-dimensional preservation, the finding of these specimens, despite their fragmentary nature, is regarded as significant.