When a specimen is flipped over one has to think in reverse regarding where the specimens various parts are then located. Boney processes that pointed one way, now point in the reverse. Bone processes that pointed up are now pointing down. So do I cut or grind away the plaster jacket here? Maybe not, there was a rib or limb bone there. Usually one just guesstimates where everything is but as the incredible Gorgosaurus skull is close to the original field jacket I did not want to do this. So what to do? I tried something different and have never tried before.
First I took a red marker pen and drew a line around the skull, several centimeters away, thereby marking a safe buffer zone. Then using that line as a guide, I drilled a series of spaced holes with a power drill and a long bit. The holes were drilled all the way through the jacket. In curved areas the holes were drilled closer together. When the block is flipped over, these holes will appear and the holes can be reconnected with a red felt pen and thus accurately outline the skull. As the jacket is then pulled and cut apart, the holes will always be there until the very end to remind me where the skull is.
I also spent a couple hours photographing the specimen under various light levels, angles and distances. These pictures will serve as a valuable reference when I prepare the other side and will be useful for future researchers.