Description of Priscinachus elongatus n. gen., n. sp., and Priscinachidae n. fam. for the earliestspider crab (Crustacea, Decapoda, Majoidea),from the French Cretaceous (Cenomanian)

摘要

Priscinachus elongatus n. gen., n. sp., is based on four specimens from twolower Cenomanian exposures, separated by 85 km in the western Paris Basin.It is the earliest known spider crab, the Majoidea being previously knownonly from the lower Eocene. Priscinachus elongatus n. gen., n. sp. deservesits own family, the Priscinachidae n. fam., within the Majoidea Samouelle,1818, due to the original combination of characters which is not foundwithin any other majoid family. In both exposures, the fossils are preservedin a hard-ground, deposited in a shallow but open sea, in a transgressivecontext. Decapod fossils have been transported and often broken beforedeposition.