Taphonomy

Taphonomy is the study of processes that influence the preservation of potential fossils. This field encompasses the disciplines of biostratinomy, the study of processes affecting organism remains or traces prior to their final burial, and fossil diagenesis, the investigation of phenomena affecting potential fossils after burial. Recently, taphonomy has developed both as a means of assessing bias in the fossil record and more positively, as a critical tool for paleoenvironmental analysis. Taphonomic analyses and fossil geochemistry provide valuable information on the physical and chemical parameters of environments. The assumptions of uniformitarianism are applicable at this level because the physical and chemical properties of the skeletons of organisms have probably been invariant through geologic time, despite the nonuniformity imparted by evolution. The taphonomic features of trilobites (e.g., articulation of delicate skeletal elements) may provide unambiguous evidence for episodic sedimentation; conversely, highly corroded fossil material provides a distinctive signature of long-term condensation.

Articulated specimens of trilobites, while generally uncommon, may be abundant in some beds. Moreover, the totally mineralized body parts of trilobites commonly have been preserved nearly unchanged for at least 520 million years. However, preser-vational features of fossil specimens can be used to decipher the taphonomic history of these specimens and provide useful clues as to original environment.

The structural complexity of the trilobite exoskeleton and the process of molting of the exoskeleton during growth increase the number of fossil parts that can be generated by a single individual. Trilobite skeletal parts can be found in a majority of fossilif-erous localities in New York, and well-preserved cephala and pygidia are generally identifiable to species. With most organisms, like bivalves or gastropods in which the skeletal growth is by accretion, the fossil is evidence of the death of an individual. Conversely, with trilobites, the presence of body parts is not a simple indicator of population density.

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