Dinosaur Dreaming

Fossil preparation

The fossils prepared in the Monash PalaeoLab are not quite like the stereotype specimens you see in films like the Jurassic Park series. Instead of being able to simply dust the dirt matrix away from the bones with brushes, Victorian Cretaceous fossils are encased in a sandstone and mudstone rock matrix which is often much harder than the bones themselves. The PalaeoLab has pioneered methods of fossil preparation and conservation not used anywhere else in the world.

Mechanical Preparation

The only way we can find fossil bones in rocks from Inverloch or Dinosaur Cove is by breaking the rock. What the lab gets given to work on is a broken rock encasing a broken bone. Before the rock can be removed the exposed bone must be hardened using a chemical that soaks into the bone and hardens its structure. Any fine cracks are injected with glue to prevent the bone or tooth from exploding apart once the rock supporting it is removed. Once the exposed bone has been treated, the rock is taken to the prep lab.

The prep lab houses compressed air tools and magnifiers, and here the rock is removed from the bone using pneumatic tools, like tiny jack-hammers. These work the rock away from the bone, grain by grain. For extremely delicate specimens, like jaws, teeth, skull material, or very thin bones, a fine needle is used to gently pry away the rock grains one by one under a microscope, without touching the bone at all. As new bone is exposed it is also treated with hardening chemicals, and then the work continues.

Eventually the bone is freed from the rock, and can be examined to work out what it may possibly be from by comparing it with bones from other known species from Australia and elsewhere in the world. The average time from getting the rock into the lab to a final bone is about 3 days, but some specimens can take as long as 8-10 days.

Chemical Preparation

For some specimens, where the rock matrix has been exposed to groundwater, the grains may have been cemented together by calcite or limestone (CaCO₃). These are very resistant to the use of mechanical preparations, as the cement makes them much harder rocks. In these cases we have found that the use of dilute acids, such as formic acid or dilute vinegar, helps to dissolve the cement and the sand or mud grains can then be mechanically removed from the around the fossils.

The bones must be hardened before, during, and after the acid treatment and coated with protectant chemicals, as prolonged exposure to the acid can start dissolving some of the bone material as well.

In other cases, such as fossil material from Gogo in Western Australia, and Bullock Creek in the Northern Territory, the fossils are encased in limestone, and acid preparation is the only thing necessary to remove the bones from the matrix, which simply dissolves away.