The last of the preparation is now being done on the Gorgosaurus. Several bones were completed on January 19th. These were the first ones to be completely finished. The nature of the rock is cracked and crumbly and despite best efforts, some rock along the edges and underneath the bones has fallen away. The bone is not properly supported and the missing rock needs to be replaced. The femur was badly affected this way. To remedy this (shown in a series of 4 pictures), I mixed some thick glue with sand from the Gorgosaurus block. Waste rock was broken up and ground into sand and dust, using a short length of a hardwood broom handle as a rolling pin. The resultant sand/dust was poured into the jar of glue and stirred together. The result was a thick paste which could be made more runny by adding more glue, or thicker by adding more sand. This paste was applied to the undercuts using a small metal spatula. Because the paste was so thick, it was easy to work and retained its shape. It dried hard in a couple hours and the bone is now safely supported. The support can be removed in the future if need be by squirting acetone onto it and removing the resulting paste. Also, once the paste is hardened, it can be shaped with an airscribe if needed. The final result is quite convincing as “real rock”.
The final treatment of the completed bones is a very thin coating of glue, made so thin that it does not sit on the bone surface, but soaks in. It seals up any remaining microcracks and dissolves and old glue on the surface. The provided picture with the brush shows part of the now fully prepared ischium, with the surface treatment of glue. Final preparation of the rest of the skull and skeleton will go quickly now.
All photos here and in the series are owned by Darren Tanke and the Royal Tyrrell Museum.