In the course of our new project ‘Unlocking the secrets of cremated human remains’, we had the opportunity to CT scan recently excavated urns from St. Pölten. Now, why would one want to do this? There surely is not much to do for the patients in the urns!
In archaeological practice, Bronze Age urn burials are rarely found intact when they are excavated. Ploughing or other, later disturbance of the burial grounds has often destroyed the upper part of the burial. During rescue excavations, there is rarely the time to document all pieces of cremated remains, and urns are frequently emptied to get the remains to the osteologist for analysis. However, this case was different. St. Pölten’s city archaeologist Ronald Risy offered us two recently excavated urns excavated en bloc. This means that the entire urn, including the surrounding soil, had been wrapped in cling film and plaster for stabilization and recovered as a whole. This is the only way to preserve the whole context – the exact location of all cremated bone fragments, their position relative to each other, to grave goods within the urn, and to the filling material.
A detailed analysis of this contextual information can answer a number of questions about the burial ritual. How was the urn filled? Did Bronze Age people recognize the individual bones and place them in a specific anatomical order? Did they select specific parts of the body? Did they include charcoal and ash from the funerary pyre? Which dress elements and tools were cremated with the body and placed alongside the cremated remains? Did Bronze Age people fill the remaining space of the urn with pebbles or soil? Which taphonomic processes acted on the urns after burial?
It is a well-known truth that all excavations are destructive – they destroy the original layers, contexts and sequence of deposition despite archaeologists’ best efforts to record all possible information. It is therefore a good idea to document the burial context of the urn in as much detail as possible, and CT scans are an amazing tool to achieve the best possible visual documentation. Thanks to Fabian Kanz and his colleagues, we got an out-of-hours appointment at the Dental Clinic of the Medical University of Vienna.
The images and 3D models from CT scans cannot only guide the micro-excavation (it is always good to know what to expect!), but also help with a typical problem of analyzing cremated remains: the bones fragment further when they are excavated and handled, to the point where measurements are no longer possible. Measurements, however, are particularly important for estimating biological sex and body height. The CT scans enable us to measure the bones in situ from the images. In addition, trabecular bone is often stabilized within the urn, but falls apart when taken out. Pelvic bones, femoral heads, and other characteristic bones can be identified and in part already analyzed through the images.
The CT scans help us select the best possible strategy to disentangle soil, cremated remains and pottery. We can clearly see the location of each pottery fragment, the extent to which the urns are fragmented and how they collapsed from soil pressure. Since our focus is on getting the optimal information from cremated remains, we will compromise on the preservation of pottery if necessary. One of the urns is almost intact, the other quite fragmented. It will be exciting to take them out of their cast!
Check out a video of one of the CT scans here: