DOCUMENTING DECAPOD (CRUSTACEA) DIVERSITY AND ECOSYSTEM DYNAMICS IN THE LATE JURASSIC OF CZECH REPUBLIC

Eighty-one specimens of existing species of fossil brachyurans (crabs) and anomurans (squat lobsters) were collected from the Štramberk Limestone of late Tithonian (Late Jurassic) age over a two day period. The Štramberk Limestone is exposed in a quarry near the village of Štramberk, Czech Republic, which is located in the eastern part of the country. One new species of Glaessneropsis was also discovered. Among the specimens collected, 14 species and 10 genera were identified. One-hundred years of literature accounts of the Štramberk Limestone have yielded approximately 19 genera in about 40 species of Decapoda, suggesting that the quarry locality is relatively diverse in terms of decapod taxa. In addition, the opportunity to study such a diverse assemblage of specimens from a single location, representative of an entire ecosystem and its associated fauna, is unusual for the Decapoda. Examination of thin sections along with visual inspection of specimens indicates that the crabs and squat lobsters each were found associated with different species of corals, algae, brachiopods, and echinoid spines, suggesting that each had a specific niche that they inhabited in the ecosystem. Some brachyurans were associated with coral, whereas others inhabited fine grained limestone. The average brachyuran specimen size ranged from a few millimeters up to 2.5 cm. The relatively small size appears to be an adaptation to cryptic environments within reef complexes and associated habitats. A large brachiopod over 3 cm was also found, unusual in being larger than the crab specimens. Some of the brachyurans collected were encrusted with a parasitic worm on the dorsal carapace, which appears to be species-specific. Research funded by NSF EF-0531670 to Feldmann and Schweitzer.