Boucher, Lisa .
Evaluating taphonomic biases and their effects on diversity and abundance estimates: an example using Cretaceous macrofloral assemblages.
Although relatively rare in situ sites exist, most of the plant fossil record is preserved in parautochthonous or allochthonous sites. These latter sites are a valuable source of paleoecological data, provided taphonomic and sampling biases are assessed when measuring and interpreting plant diversity and abundance data. In this study, Late Cretaceous compressions, consisting mainly of pteridophyte, gymnosperm and angiosperm leaves, were collected from several sites representing six floodplain subenvironments of the Fruitland-Kirtland Formation in northwestern New Mexico. Relative abundance and diversity were calculated using a line-intercept method at each site. To help quantify taphonomic bias, data collected for individual specimens included leaf position relative to the bedding plane, type of leaf damage, and extent of leaf completeness. Plant fossils were also classified according to their biotic characteristics, including overall size and shape, thickness and texture, and petiole diameter. In addition, detailed sedimentological information was collected at each site. Then, multivariate analyses of the plant fossil and sedimentological data established taphonomic signatures for each site. The results suggest that subenvironments within floodplain settings have subtle differences in their taphonomic signatures as measured by these leaf parameters. In particular, the type and extent of damage to the leaves were the most notable and have implications for interpreting abundance and diversity data. Furthermore, in this study most of the assemblages represent local flora as deposited within fluvial subenvironments, and the additional taphonomic and sedimentological data provide a means to more accurately interpret plant diversity and abundance along heterogeneous landscapes.
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1 - University of Nebraska Omaha, Department of Biology, 6001 Dodge Street, Omaha, Nebraska, 68182-0040, USA
Presentation Type: Oral Paper
Location: Salon G - Austin Grand Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 10:30 AM