Underwater cave proves a treasure trove.

• Position: Paleontology

Lagerstatten--that word sends a shiver of excitement up and down the spine of every paleontologist. In German, the word means "storage place" or "deposits" but, in paleontology, it has come to mean a very rich fossil deposit that contains complete or nearly complete specimens that sample a wide variety of the creatures living at a certain time.

Lagerstatten are quite rare. Some of the more famous examples are the Burgess Shale in Canada, which preserves soft body outlines of 530,000,000-year-old Cambrian animals; the Jurassic Solenhofen limestones in Germany, where the famous Archaeopteryx is found; and the middle Eocene Messel Oil Shale in Germany, which preserves whole skeletons of many birds, mammals, reptiles, amphibians, and insects.

The latest and most exciting Lagerstatten is the discovery of subfossils at Aven Cave in Madagascar's Tsimanampetsotsa National Park. It was known to local people, but not reported to the scientific community until an Australian cave diver saw it. The cave and its specimens are underwater. The specimens are called subfossils, because they are not old enough to have completed (or in some cases even started) the fossilization process.

A joint team...