Instead, a piece of rock large enough to be sure that it contains the whole fossil is chiseled out. Fossils found in the mud of a river bed or in loose sand may be washed on the spot. If the fossil site is large, it may have to be cut up with a stone saw. This requires professional skills. In addition, permission must be obtained from the owner of the site.
Professionals photograph the whole site before starting to work.
The pieces are numbered as they are cut out, so that they can be put together exactly as they were found. Sometimes a fossil that has weathered out of the rock has become soft and crumbly in the weathering process. In that case a different procedure is followed. Burlap is soaked with wet plaster of Paris and wrapped around the exposed end of the bone. Then the block of stone is cut out, and the whole is wrapped in more burlap soaked in plaster of Paris before it is crated for shipment.