New Crab Species and Genera from Jurassic (Oxfordian) Coral Reefs and Comparison of Decapod Abundance Between Coral and Sponge Environments in Dobrogea, Romania

Analysis of the fossil decapod faunas in coral reefs from localities at Topalu and Piatra in Central Dobrogea, România, yielded five new species and one new genus belonging to Prosopidae. Comparison of the abundance and diversity of decapod faunas from these Jurassic coral reefs with the abundance and diversity of decapod faunas from sponge-algal reefs in the same geographic area and the same age, middle Oxfordian, has led to some interesting paleoecological dichotomies. In the coral reef environments are decapods from six families in seven genera, ten species, and 30 specimens, including the new taxa. In the sponge reef environments are three families with four genera, five species, and 22 specimens. Between these two different types of environments there is only one common genus but no common species. The number of specimens is similar, but diversity is markedly different. The lack of shared species and only one shared genus suggests that the environments selected for different adaptations, leading to niche partitioning within and between habitats.

The higher abundance and diversity in the coral environments may reflect a higher number of niches available for decapods to inhabit; water depth; oxygen differences; and difference in energy levels in the two environments, making coral reefs a more suitable environment for decapods to inhabit.

Investigation of this pattern is ongoing. Research supported by NSF INT-0313606 and EF-0531670 to Feldmann and Schweitzer and CNCSIS Grants 304/2003-2005 and 1022/2006-2007 to I. Lazar.