Recovery rates of osseous material with variable taphonomic color change
Date
2025
DOI
Authors
Version
OA Version
Citation
Abstract
The present research examined recovery rates and distances of bones with different taphonomic color alteration. The project examined the success rates using researcher-guided walk-throughs of a simulated outdoor environment of bone dispersal, noting distance from bone when first recognized, bone type, and bone color throughout the trials. The simulated environment was established using a grid system and randomized bone placement. The search group used in this research was the Special Emergency Response Team (SERT) of the Massachusetts State Police (MSP). Recovery rates were determined by the total number of bones per type recovered from the designated grid.Regarding bone color, the author hypothesized that sun-bleached bone would be recognized first and from the greatest distance due to its starker contrast from natural decomposing plant materials on the forest floor as opposed to bones with soil-stained colors. The control bone sample are natural bone color with no taphonomic changes from an outdoor environment. The sun-bleached bones, on average, were recognized from the greatest distance when compared to the averages of soil-stained and control bone samples. Sun-bleached bones were spotted at an average distance of 8.76 m ± 7.75 m, while soil-stained bones were spotted at an average distance of 4.09 m ± 2.79 m. The control sample was spotted at an average of 6.73 m ± 5.40 m. After running a two-way ANOVA test, the interaction between bone color and distance was significant, with a p-value of <.001. The overall success rates of recognizing bone based on its color were sun-bleached bones at a 100.0% recovery rate (60/60), control bones at a 96.7% recovery rate (58/60), and soil-stained bones at a 70.0% recovery rate (42/60).
In terms of bone type, the author hypothesized that smaller bones, such as vertebrae, would be missed most often because of their relative size to other objects on the forest floor, and that skulls would be spotted from the furthest distance as a result of their larger size. The results of this study showed that skulls were spotted from some of the greatest distances, the furthest at 34.25 m and only surpassed by one long bone at 40.25 m, and that vertebrae were indeed missed most often, accounting for 14 of the 20 bones missed across all six trials (70%). Skulls were spotted from an average distance of 9.31 m ± 7.04 m, long bones from an average distance of 6.63 m ± 6.30 m, pelves/scapulae from an average distance of 6.67 m ± 5.64 m, and vertebrae from an average distance of 3.39 m ± 3.20 m. After running a two-way ANOVA test, the interaction between bone type and distance was significant, with a p-value of <.001. The overall success rates of recognizing bone based on type were skulls at 100.0% recovery (36/36), long bones at 97.2% recovery (70/72), pelves/scapulae at 88.9% (32/36), and vertebrae at the lowest recovery rate of 61.1% (22/36).
In addition to bone color, bone type, and distance in their relationship to recovery success, trends in success rates for individual days as well across all trial days were tested for significance using three separate Mann-Kendall tests. The results of these tests showed that there were no significant trends in the changes of recovery rates.
Previous research shows that even expert level recovery teams miss osteological evidence. Training and awareness of these teams can be improved by furthering our understanding of previously unresearched factors that affect our ability to recover bones.
Description
2025