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Tang - Detecting stability and change in fossil communities: the need for temporal- and scale-dependent perspectives

Detecting stability and change in fossil communities: the need for temporal- and scale-dependent perspectives

Carol M. Tang

California Academy of Sciences, 875 Howard Street, San Francisco, CA 94103, USA, ctang@calacademy.org

The strict application of ecological patterns and processes to the fossil record is severely limited because of loss of soft-bodied flora and fauna, difficulties of measuring biomass, virtual inability to reconstruct direct biotic interactions, and most significant of all, time averaging of individuals which never lived contemporaneously. Documented patterns of paleocommunity stability should more accurately be compared to the neo-ecological concept of resilience rather than resistance. While succession and other short-term processes can only be examined under unique preservational conditions, time-averaged "paleocommunities" possibly spanning thousands of years do allow for the study of patterns and processes in evolutionary paleoecology.

Molluscs are a good system with which to ask paleoecological questions because they exhibit a range of trophic strategies, are geographically distributed, have a long fossil record, and inhabit a number of ecological and environmental niches. In addition, many taxa have good preservational potential. However, even with molluscs, detailed sedimentological, paleoenvironmental, and taphonomic studies should be employed to assess the limitations of paleocommunity analysis.

For example, in the right depositional systems, paleocommunities can preserve local geographic patchiness and short-term environmental excursions; even with time averaging and transport of individuals, a great amount of small-scale geographic and temporal resolution can be obtained using the appropriate proxies given preservational biases. In this talk, many different proxies including species abundance, individual abundances, species presence/absence, comparison of left and right valves, morphometric and paleocommunity structure are compared to reconstruct different paleoecological conditions exhibited by mollusk-dominated Neogene marine fossils of the Dominican Republic.


next up previous
Next: Todd - Missing pieces Up: Special Symposium - From Previous: Scheltema - The Evolution
Peter Roopnarine 2005-04-12