关键词：
Taphonomy
Taxa
Specimens
Signatures
Gravel
Mollusks
Yield point
Sample size
Inlets
Corals
摘要：
The sensitivity of taphonomic signatures to a battery of common sampling and analytic procedures is tested here using modern bivalve death assemblages from the San Bias Archipelago, Caribbean Panama, to determine (a) the magnitude of methodological artifacts and, thus, the comparability of taphofacies patterns among studies;and (b) the most efficient and robust means for acquiring damage profiles (taphonomic signatures) of death assemblages both ancient and modern. Damage frequency distributions do not stabilize below sample sizes of 120-150 individuals. Using damage to the >8 mm portion of the assemblage as a baseline (interior damage only, fragments included), it is found that qualitative trends among environments (higher damage levels in reefal skeletal gravel versus mud) and the rank-order importance of taphonomic variables per environment (intensity of damage from encrustation, boring, fine-scale alteration, edge-rounding, fragmentation) are robust to most methodological decisions. The exception is the use of target taxa: of three genera tested, only one was sensitive to the same suite of environmental differences as the total-assemblage, and taxa had disparate rank-ordering of variables. In contrast to the general robustness of qualitative trends, quantitative damage Levels are affected significantly by methodology. Specifically, the measured frequency of damage is generally lower for finer size fractions and finer sieve sizes, for whole shells versus fragments, for taxonomically well-resolved specimens, for infaunal versus epifaunal species regardless of mineralogy, and for interior surfaces versus exterior or total surface area of shells. Full frequency-distribution data on states of taphonomic damage are most powerful for differentiating samples, but if single-value metrics are desired, the frequency of high-intensity damage is more powerful-and shows less between-operator variance-than presence-absence data or average damage state. To maximize the detectio
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详细信息
中文科技期刊
