Dinosaur palaeontology. Researchers applying a plaster cast to a fossil dinosaur bone at a site in the Aude valley in southern France. The plaster helps to protect the exposed fossil, especially when it is transported to a laboratory for cleaning and classification. Sites such as this on the northern part of the Pyrenees mountains have yielded many fossils of titanosaurs and ankylosaurs, dating from the late Cretaceous period about 70 million years ago.