Article: Moults of Dakoticancer overanus, an Upper Cretaceous crab from the Pierre Shale of South Dakota
Gale A. Bishop
Of 4,000 specimens of fossil decapods collected from three stratigraphically different localities in the Pierre Shale (Upper Cretaceous, Maestrichtian) of South Dakota, twenty specimens of the brachyuran Dakoticancer overanus Rathbun were found preserved in Sailer's position. Several of these specimens have the portion of the carapace which lies outside pleural sutures still attached to the sternal plastron, proof that they are exuviae. The part of the carapace between the pleural sutures is completely overturned on each specimen and rotated on most specimens. The escaping movements of the moulting crab probably caused water currents which in turn caused the central part of the carapace to slip backward over the moulting foundation resulting in the new type of Salter's position.