| Differential preservation of bone due to varying local-to-global terrestrial environmental conditions is recognized as a pervasive bias throughout the fossil record. Furthermore, the distribution of these environments has varied considerably through time, profoundly affecting what is preserved in the fossil record, and where. Little is known regarding how environment-specific decay and diagenesis affect terrestrial bone preservation, and ultimately our reconstructions of paleoecology, diversity, and biogeography. To investigate short-term processes critical in the decay and diagenesis of buried bone, I performed a 14-month controlled taphonomic experiment which explored the individual and collective effects of (1) sediment hydrology and organic content [sand vs. silt/humus], (2) bone size [deer vs. rabbit vertebrae], and (3) plant association [gymnosperm vs. angiosperm] in controlled laboratory microcosms. Data included the measurement of leachate for calcium (Ca) using DCP-AES, sediment pH, bone mass change, and CT scanning to quantify changes in bone density. Results show that plant type, sediment type, and bone size all significantly interact to influence bone decay, with the effect depending on the context. Sediment type had the strongest influence overall, driving differences in pH, anoxia, mass/density loss, and Ca leaching. Plants were found to release substantial amounts of Ca, but did not differ by type. This experiment suggests that the process of bone decay: (1) is reduced by the presence of plant material, (2) depends on the surface area to volume ratio of a bone, and (3) is sediment specific: high-flow sand-dominated sediments erode bone at a high rate, while low-flow silt/humus-dominated sediments affect bone more slowly. Comparison of experimental data with fossil vertebrate distribution from the Late Jurassic Morrison Formation of North America suggests that the same factors are important for fossil preservation, but environmental differences exert a strong control over these processes. Furthermore, changes to local environmental conditions brought about by global climate patterns may have a profound impact on fossil preservation, affecting the spatial distribution of vertebrate remains over geologic time. This study has important implications for taphonomic interpretation of individual fossil sites, facies control of fossil preservation, and even large-scale paleobiogeographic reconstructions. |
