Copyright © 2007 Dorling Kindersley When a fossil arrives in a
laboratory, it is usually embedded in a chunk of the rock it was
found in. The first job for the specially trained technicians,
called preparators, is to free the fossil from the rock and
clean it up. Sometimes they can remove the rock from the fossil
with chemicals. The fossil is left in a bath of acid for several
months while the rock around the fossil, called the matrix,
dissolves. Preparators also repair bones, strengthen any weak
parts with glues and resins, and may make missing bones if the
skeleton is to be reconstructed. Preparation is very time-
consuming work. The Tyrannosaurus skeleton in the Field Museum
in Chicago, USA, for example, took 12 people a total of 25,000
hours to complete. To order this book direct from the publisher,
visit DK's website.