USING EPOXY CASTING TO INVESTIGATE MICROBORINGS IN ANCIENT HARD SUBSTRATE COMMUNITIES

Microborings are produced by microscopic organisms which excavate hard substrates by chemical or mechanical means. These microborings are not visible without a microscope, and most of their complexity remains hidden under the surface. Epoxy casting of microborings allows us to see the hidden complexity three dimensionally. In this study, microborings in Jurassic shells were cast through a two-component cold mounting procedure. The shell was then removed after casting. With this epoxy casting process and further examination, knowledge of the paleoecological and paleoenvironmental implications of the shell surfaces can be explored. The epoxy casting was done with a vacuum impregnator system. The machine allows for a nearly air-free space, thus removing air bubbles from the hardening epoxy. The vacuum is later slowly broken to allow air to rush in and force epoxy into the pore spaces within the sample. The epoxy hardens to form a cast of any allowed cavity within the sample, including microborings, cracks, and crevices. The epoxy casting process was tested and used on fossil oysters from the Jurassic of Dorset in southern England. These fossils showed potential for microborings based on previous studies. The epoxy casting of the materials has shown a variety of biogenic and inorganic features on the shell surfaces which add to our paleoecological interpretation of these communities.