MIDDLE TRIASSIC SHRIMP FROM THE LUOPING LAGERSTäTTE, CHINA: IMPACT OF TAPHONOMY ON SYSTEMATICS

The decapod fauna from the Early Triassic (Anisian) Luoping Lagerstätte from Yunnan Province, western China, is comprised of lobsters and shrimp. Of these, the shrimp are far more numerous in terms of numbers of specimens but are less speciose. The shrimp are considerably more enigmatic. Preliminary evaluation of over 300 specimens suggest that at least two species are present; however, the problems of identification are exacerbated by a strong taphonomic overprint. Shrimp are characterized by laterally compressed bodies encased within weakly calcified, flexible cuticle, and as a result are typically preserved as specimens flattened in lateral aspect. This mode of preservation is well documented by the numerous shrimp fossils known from the Late Jurassic Solnhofen fauna in Germany. Description and comparison of specimens thus preserved is relatively straightforward. In contrast, the shrimp from the Luoping Biota pose vexing taphonomic issues making their description and classification difficult. Rather than being preserved simply as laterally compressed individuals, specimens are variously twisted and distorted so that parts of specimens may be seen in lateral aspect whereas other parts of the same specimen are rotated such that parts of both sides of the individual are exposed. The rotation, coupled with compression renders recognition of morphologic features confusing. Other specimens are preserved in dorsal aspect and some in ventral aspect. Further, rather than having been preserved as compressed, relatively pliable cuticle, many specimens are crushed and fragmented in a manner suggesting brittle deformation of the cuticle which adds to the difficulties in identification. The unique combination of plastic and brittle deformation of the cuticle suggests a preservational scenario in which specimens exhibiting brittle deformation were dessicated whereas those deformed plastically were not. The work was supported by NSF OISE 1126137 to Feldmann and Schweitzer and Chinese Geological Survey grants 1212011140051, 1212011120621, and 1212010610211.