On 23 September a young naturalist, thousands of miles from home and frequently seasick and homesick, found the fossil of an enormous skull embedded in soft rock. It took Charles Darwin three hours to chip it out of the cliff face at Punta Alta in Argentina, and hours more to lug it back to base. He arrived with it long after dark at the ship which became the most famous in the history of natural science, the Beagle.
Darwin was only 24, a college dropout from his medical degree who had done a crash course in geology in order to join the voyage. His fossils, much less famous now in the history of how he came to publish his theory of evolution by natural selection than his observations of wildlife, are among the treasures of the Natural History Museum in London. They are still of interest to scientists all over the world but many of the originals are almost too fragile to handle.
The NHM this week launches an ambitious project to scan and digitally recreate the fossils in 3D , in such minute detail that they can be studied by scientists as well as pored over by members of the public. One of the first completed has just been digitally dissected by a scientist in Montpellier in France. The digitisation also guarantees that a permanent record of the bones will be preserved as scientific tests continue. Carbon dating has recently confirmed a date for one which Darwin could only have guessed at from the rock layer in which he found it β just 12, years old, so very close to the extinction of its species β and the NHM will now attempt to extract DNA from it.
Its curved teeth led Darwin and fellow scientists to wonder if it was an gigantic rodent, but it was eventually identified as a distant relative of a rhinoceros β and the last member of a group of South American mammals stretching back 60m years. One batch contained a missing section of a skeleton which had already been sent back by another collector β the creature whose skull Darwin had chipped out of the cliff face.
They were the remains of Megatherium, a ground dwelling relative of modern tree dwelling sloths β but Megatherium was the size of a car, the largest and heaviest land mammal ever to live in South America.
