Taphonomic experiments fixed and conserved with Paraloid B72 resin via solvent replacement

Taphonomic experiments offer a powerful tool with which to interpret the influence of decay and mineralization on the quality and completeness of Earth’s fossil record. Experimental attempts to replicate the exceptional preservation of organisms, or to test specific preservational hypotheses, have had some – albeit limited – success in promoting early diagenetic mineralization surrounding soft tissues. However, such experiments often employ unrealistic physical or chemical conditions, or require highly disruptive sampling procedures in order to
determine the extent of decay and mineralization. These shortcomings narrow the range of hypotheses about exceptional preservation that can be meaningfully tested. Here, we propose a novel method of soft sediment fixation that permits the stabilization of entire decay experiments for sectioning and microanalysis. Experimental vessel contents are dehydrated by submersion in molecular-sieve-dried acetone, and then impregnated by water-sensitive Paraloid B72 resin. Evaporation of the acetone produces inert and consolidated dry samples,
with a thin meniscus of Paraloid B72 coating all pore spaces within the sample. The consolidated samples are amenable to study by techniques comparable to those applied to geological materials, such as thin sectioning and microanalysis. Application of this method to a wide range of substrates demonstrates that this methodology can produce effective stabilization of samples, including unconsolidated sands and organic-rich substrates, with a chemically inert polymer. Although there is some volume-loss, and possibly enhanced
precipitation associated with dehydration, the method is otherwise minimally disruptive to sediment grains, authigenic minerals, or organic remains. It can therefore be coupled with sacrificial sampling at discrete time intervals to monitor taphonomic processes occurring in carcasses entombed within sediments at a high spatial and temporal resolution. The methodology may also be relevant in curatorial settings for certain organic-rich materials. Taphonomy, Paraloid B72, solvent replacement, preservation.