Meeting Abstract

81.5  Sunday, Jan. 6  Assessment of Jurassic Brachyuran (Crustacea: Decapoda) Diversity and Paleoecology FELDMANN, R. M.*; SCHWEITZER, C. E.; Kent State University, Kent, Ohio, 44242; Kent State University, Kent, Ohio, 44242 cschweit@kent.edu

Examination of type and newly collected material indicates that the Jurassic Brachyura, historically assigned to three families, are much more diverse than previously reported. Assignment of fossil brachyurans from the Jurassic at the family and genus level has typically been based upon groove and carapace regional morphology. Whereas these features are indeed important, our studies indicate that there is remarkable diversity in the nature of the rostra, orbits, anterolateral margins, and even within the development of dorsal carapace regions that previously has not been reported. Studies of this material have already resulted in new genera and families (Schweitzer et al., 2007a; Schweitzer and Feldmann, in press). Some of the orbital configurations are reminiscent of members of extant superfamilies, such as the Homolodromioidea and the Majoidea; others appear to be unique. Some lineages appear to be extant, whereas others are extinct, a common pattern that seems to have been repeated frequently in the evolution of the Crustacea. Exploration of these relationships is ongoing. Further, comparison of fossil brachyurans from a variety of paleoenvironments, including sponge-algal bioherms, coral reefs, and soft-bottom, muddy environments, shows a remarkable degree of niche partitioning (Feldmann et al., 2006; Schweitzer et al., 2007b). Some genera seem to have preferred sponge and soft-bottomed environments, whereas others have thus far only been recovered from coralline facies. This work is supported by NSF grants INT-0313606 and EF-0531670 to Feldmann and Schweitzer.