Cuticle Microstructure from the Late Jurassic Shrimp Aeger Sp

Cuticle microstructure from a Late Jurassic shrimp Aeger sp. collected from the Nusplingen Lithographic Limestone 100 km southwest of Stuttgart, southern Germany, was examined and compared with cuticle from modern shrimp in an effort to identify taxonomically useful characters. The Nusplingen Lithographic Limestone, a Solnhofen-type lithographic limestone, preserved the cuticle in sufficient detail to allow comparison with cuticle collected from extant shrimp within the superfamilies Penaeoidea Rafinesque, 1851, and Caridea Dana, 1952. Preliminary results show that the cuticle of extant species within these superfamilies contains an exocuticle with laminations that are thicker than those of the underlying endocuticle. The presence of thicker laminations within the exocuticle is in contrast to that found within crabs and lobsters, including a late Middle Jurassic representative of the lobster Eryma von Meyer, 1840, that exhibit an exocuticle that is more finely laminated than is the endocuticle. Based on the current data, it appears that the cuticle of shrimp can be differentiated on this basis from that of lobsters and crabs, and this difference has existed at least since the Jurassic. Based on illustrations in the literature, pelagic euphausiids and mysids exhibit an exocuticular morphology similar to that of the shrimp examined. This architecture may be an adaptation to pelagic lifestyles (Pütz and Buchholz, 1991). Alternatively, it may be phylogenetically significant, suggesting a sister group relationship between the mysids or euphausiids and the Decapoda. This research is supported by NSF Grant EF-0531670 to Feldmann and Schweitzer.