ADDITIONS TO THE MIDDLE AND UPPER JURASSIC DECAPOD FAUNAS FROM CENTRAL AND SOUTH-EASTERN EUROPE

During the Jurassic, decapods experienced a major radiation and diversification event in extensive carbonate reefal habitats within the Tethys basin in Central and Eastern Europe. This area is considered to be the probable site of origin of the brachyurans (true crabs) and an area of diversification for other types of decapods. Jurassic brachyurans were generally extremely small, with maximum length of 15-20 mm, whereas the representatives of the orders Glypheoidea, lobsters, and Thalassinidea, mud shrimps, were much larger. The specimens we focus on here were collected from România, in Central Dobrogea, and Czech Republic, in the Štramberk area. One belongs to the brachyuran family Tithonohomolidae Feldmann and Schweitzer, 2009. The others are glypheoid lobsters of the Mecochiridae Van Straelen, 1924 [imprint 1925], and thalassinoids referable to the family Axiidae Huxley, 1879. All are preserved in calcareous deposits, and they do not conform to the general rule for size. In this case, the partial brachyuran is very large, 65 mm in length, and the lobsters and mud shrimps are very small, 9-10 mm long. The size differences between brachyurans and lobsters/mud shrimps are due to their life style: the brachyurans were small because they lived in the open spaces within the reef framework, whereas the lobsters and mud shrimps lived on the reef structure or slope, so they did not need to fit into the empty spaces of the reef. The large brachyuran in this study may not have lived within the reef itself and may not have relied on concealment within small crevasses in the reef structure; the small lobsters and mud shrimps may have lived within the reef. Research supported by NSF grants INT-0313606 and EF-0531670 to Feldmann and Schweitzer.