Paper No. 3
Presentation Time: 9:30 AM


FOSTER, William J., Department of Geological Sciences, University of Texas at Austin, 1 University Station C1100, Austin, TX 78712 and TWITCHETT, Richard J., School of Geography, Earth and Environmental Sciences, Plymouth University, Drake Circus, Plymouth, PL4 8AA, United Kingdom,

The Late Permian extinction event was the largest biotic crisis of the Phanerozoic with up to 74% of benthic marine invertebrate genera becoming extinct. Understanding biodiversity changes through the Permian-Triassic interval requires more than just taxonomic richness data, however, especially when trying to investigate the impact of changing environments on biota. Paleoecological data used for investigating biodiversity changes through this interval include: alpha diversity, tiering, taxonomic dominance and biosedimentary fabrics (e.g. ichnofabric index), with each providing a different perspective on the extinction and recovery. In this study we used two large, vetted genus-level databases of occurrences and range-through data for marine benthic invertebrates, compiled from the literature and supplemented by the Paleobiology Database. Each genus was assigned a score for its motility, feeding and tiering using established methodologies. Changes in the total ecospace occupied by the benthic fauna were assessed both temporally, through the Late Permian to Middle Triassic interval, and in different paleolatitudes, oceanic settings and depositional environments. Despite the magnitude of the extinction event only one mode of life was completely eliminated globally. Occurrence data over estimate the extinction magnitude and loss of ecospace, due to sampling biases and the Lazarus effect. At local and regional scales, ecospace was dramatically reduced in tropical ecosystems, but those at higher latitudes suffered less change, at least initially. Reef ecosystems and basinal settings were largely vacated across the boundary, but inner shelf settings were less severely affected. These differences further highlight the complexity of ecosystem response to the Late Permian extinction crisis and through the recovery period. The data also serve to highlight where gaps in knowledge of certain depositional settings or regions are biasing our understanding of key intervals in the recovery, such as around the Olenekian/Anisian boundary.