Incubated eggs in a Roman burial? A preliminary investigation on how to distinguish between the effects of incubation and taphonomy on avian eggshell from archaeological sites

Microscopic analyses can be used to determine whether fragments of eggshell come from hatched, incubated or non-incubated eggs. This information is essential for their interpretation since the developmental state of eggs often permits archaeologists to draw conclusions about the function of these finds at a site. However, what has often been neglected in previous studies is the fact that not only incubation but also taphonomy may affect the microstructure of shells. This preliminary study aims to demonstrate that taphonomic processes can in fact imitate site specific dissolution features that are commonly interpreted as traces of incubation. One likely cause of this could be bacteria or other microorganisms. The paper further introduces an approach by which a distinction between taphonomic and embryonic dissolution may be possible. The successful application of this technique on seemingly incubated eggs from a late Roman burial of Ober-Olm (Germany) indicates that these shells were altered only by taphonomy and not by embryonic development as initially assumed. It is finally emphasized that the preliminary data of this investigation need to be validated in future research.