Rare species

Christie's auctioned 87 rare objects, including the three skeletons - the third that of a cave bear - owned by a private collector, as well as a collection of trilobites, or fossils of arthropods, dating from 400 million years ago.

Among them was the fossil of an angel fish dating back 50 million years, one of only five known examples of the species in the world.

A rare bezoar, a pearl that forms in the stomach of certain herbivores, also went under the hammer.

Scientists expressed concern about fossils being put up for auction.

Philippe Janvier, a paleontologist from France's Natural Science Museum, said: "while many fossils are of little interest ... major pieces which could help science progress can always turn up in such sales".