44-7 Experimental Taphonomy of Bone Surface Modifications in a Fluvial System: Paleoecological and Geoarchaeological Implications

Session: Paleontology, Paleoecology/Taphonomy, Phylogenic Morphological Patterns (Posters)

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Abstract:

Through controlled laboratory or field experiments, studies in experimental taphonomy attempt to understand processes of fossilization and their effects on biasing the fossil and archeological records. Fossilized bones that contain surface modifications are a source of insight into paleoecological relationships between different organisms (i.e. predator-prey, scavenging) and evolution of human behavior (i.e. butchery, tool manufacturing, etc.). Thus, studying the taphonomy of bone surface modifications themselves is important in contextualizing what can be gleaned from these records of past interaction. 

In order to better understand how bone surface modifications change when subjected to potentially altering surface conditions, we created and monitored cut/gouge marks on modern cow bones in an active fluvial system for two months. Using a rotary tool, we created 72 cut/gouge marks across eight bone segments, in variable combinations of wide, medium, and thin widths (3.11mm, 1.22mm, 0.91mm), and deep, medium, and shallow depths (estimated from images). We then monitored how these changed over exposure time in an upstream/rapid location and a downstream/calm location in the Bushkill Creek in Easton, PA. We observed both macro and microscopic change at one month and two month intervals. 

In comparing all cut/gouges we found wide variation in mark alteration over the study interval, and categorized alterations into six different types/modes based on mark deepening, widening, and shallowing trends through the study interval. In both locations and in all of the initial cut widths, Type IV (in which the cut/gouge both deepened and widened) was the most common. Within the downstream/calm location, there was significantly less cut “shallowing” (where the topmost layer of the bone surface was abraded/eroded) than in the upstream/rapid location. Finally, as width and surface area of the initial cut/gouge decreased, so did the diversity of alteration type/mode. 

The variety of results in this novel study highlights the importance of discretion when attempting to understand the processes and the makers of bone surface modifications. We find that significant alteration to bone surface modifications, which occurs even within small time frames, should be anticipated and may obfuscate the reliability of the information we can gather from these fossil and geoarcheological records. 

Geological Society of America Abstracts with Programs. Vol. 58, No. 2, 2026

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