How are dinosaur fossils prepared in the laboratory?

Fossil preparators are highly skilled technicians who restore the naturally fractured bones and teeth of fossil to the original state, somewhat like art conservators restore damaged paintings and sculptures.

When fossils arrive from the field, they are encased in plaster jackets, and the rock, or matrix, which was deposited around the fossils. Fossil preparation involves cutting open the plaster jacket and removing this matrix surrounding the fossil. The matrix may be soft and crumbly, when the sand or mud is poorly cemented together, or it can be extremely hard, when the sediments are well cemented. Accordingly, a wide variety of tools is required to remove the matrix and stabilize the fossil. Commonly, dental tools are used to carefully pick away sediment near the bone, along with custom-made needles composed of carbide steel. Formerly, chisels and hammers were used to remove blocks of matrix further away from the bone, but recently, smaller mechanical tools have taken their place. These include small grinding wheels, miniature jackhammers called air scribes, and tiny sand-blasters, all powered by compressed air.

When using these tools, the work is often conducted while peering through a precision microscope under high-quality lighting to make sure delicate features on the fossils are not damaged. Preparators carefully select the materials used to strengthen or repair specimens. Adhesives, glues, and fillers must stand the test of time and not become brittle or discolored, just like the materials used to conserve works of art. The types of materials used are recorded in order to aid future preparators if further preparation or repair is required.