Image: The combination of CT scanning and 3D printing is taking the discovery and recreation of ancient fossils into the 21st century Credit: Dave Stock
Sergio Azevedo was prospecting at an old railroad site in São Paulo state, Brazil, when he discovered the fossilised bones of an unknown animal. “Many times when you find a fossil in the field it’s impossible to determine how much of the ancient animal you have,” he says. “Sometimes you have just part of a bone or a tooth.” Azevedo has a solution to this perennial problem, which also acts as a safety net in case a stray hammer blow destroys an ancient fossil during excavation. Just scan it and print it.
His team at the National Museum of Brazil in Rio used a portable CT scanner to determine the orientation of the specimen in the ground, then they cut out a large section of rock to take back to the lab. There the encased fossil was probed using a more powerful scanner - and a 3D replica printed out in resin.
"This gives us safe access to the inner structures usually not accessible to conventional palaeontology," Azevedo says. Their efforts were rewarded - the animal turned out to be a new species, a 75-million-year-old extinct crocodile. As well as ancient crocs, Azevedo has also produced 3D-printed replicas of dinosaurs.
"3D printing will be a step change in the science of palaeontology once the costs come down," says Louise Leakey, who runs a virtual fossil museum, AfricanFossils.org, in conjunction with the Turkana Basin Institute and the National Museum of Kenya in Nairobi.
The method relies on an updated version of a technique called photogrammetry, which calculates the geometry of an object from photographs. To capture a 2-million-year-old Homo habilis skull, for instance, some 160 photographs of the specimen are taken from all angles. Photogrammetry software converts the images into a 3D mesh model, which can then be printed. With a CT scanner, which uses X-rays, you don’t even need to see the object with your own eyes. Fossils can be scanned while still encased in rock. The image is subjected to “virtual preparation” - software processing that digitally removes the surrounding rock.
"You can now use laser scanners to capture surface detail of delicate fossils in the field in 3D before they are excavated to provide an in situ record of a fossil or a site before it is disturbed," says Leakey. She is the daughter of the palaeontologist Richard Leakey, and granddaughter of Mary and Louis Leakey, famous for their discoveries of ancient hominids in Olduvai Gorge in northern Kenya. Scanning and excavation on a fossil of a snake skeleton in the ground at Lake Turkana will start in June.
3D printing will be a boon for classrooms too, as accurate digital replicas can be made of the rare and inaccessible specimens that make up the fossil collections in museums, without the expense of traditional casting techniques.