Non-traditional applications of fire in fossil preparation

Abstract

Fossils have been collected from the field in plaster and burlap field jackets for more than a century. These jackets support and protect the contained fossils until they can be exposed under controlled conditions in the laboratory. The challenging nature of field work and complications caused by limited time, adverse weather, or supply short-ages often produce suboptimal jackets that are less protective or difficult to remove. Often, the growth of vegetation through rock and fossils or poorly consolidated sediments compromises the stability of the jacket contents. In such cases, traditional methods of field jacket removal and fossil preparation can cause damage or destruction of the fossils within. We experimented with controlled application of flame to burn away organic materials from field jackets to facilitate safer extraction of sauropod fossils from the Late Cretaceous of Madagascar. To remove the field jacket, acetone was applied to burlap as an accelerant and then ignited with a propane torch. Combined with scoring from a utility knife, this caused the jacket to slowly weaken to the point of pliability and allow safe removal. Direct flame was also applied to plant roots infiltrating the jacket to remove them without causing vibration and mechanical damage within the specimen. Experimentation showed that with monitoring, temperatures did not reach levels that would damage the specimens through thermal shock or discoloration. Subsequent applications of these techniques demonstrate that they can be applied safely when specimens would be destroyed using more conservative methods.