Computerized tomography (CT) scans have become a vital tool for paleontologists, allowing them to see inside without needing to damage priceless items. However, scanning machines can only tackle objects up to a certain size, and until recently that size limit has hindered our understanding of some of the giant creatures that once roamed Earth.
The journal Radiology carries welcome news of the deployment of a clinical CT scanner capable of tackling big, one could say mammoth, items. To demonstrate, they have provided images of the inside of a 2-meter tusk.
“Working with precious fossils is a challenge since it is important not to destroy or harm the specimen,” said Dr Tilo Niemann of Kantonsspital Baden in a statement. Niemann’s day-to-day work concerns humans whose chests need study. Mammoths probably break the monotony, but they do create challenges.
“Even if there exist various imaging techniques to evaluate the internal structure, it was not possible to scan a whole tusk in toto without the need for fragmentation or at least having to do multiple scans that then had to be painstakingly assembled,” Niemann said. That’s changed with the new scanner architecture.
Like African elephants, but unlike their Asian counterparts, both male and female mammoths had large tusks. It is thought these were useful for both sexes for scraping bark off trees and accessing food through the snow or frozen ground, while the males probably also used their mighty ivories for fighting.
Four thousand years after the last mammoths left us, however, scientists have found other uses, such as determining the former owner’s age and any dramatic life events.
The tusk chosen to demonstrate the new capacity comes from a Swiss mammoth thought to have died 17,000 years ago and measures 2.06 meters (7 feet) long. Its curvature creates an 80 cm (2.5 feet) wide loop, making a neat fit for the 82-centimeter-wide machine. The base of the tusk is 16 cm (6.2 inches) in diameter, but its tip is missing, so its true length must have been greater.
Mammoth tusks are structured like a series of cones stacked inside each other, with the oldest at the tip. Periods of famine or other stresses can be recorded in specific cones, and can be used to find the owner’s age at the time.
The scan revealed 32 cones, providing a minimum age for the mammoth of 32 years, plus whatever was lost in the tip. Along with the annual period visible in the tusk growth, it is possible to see daily and even weekly deposition patterns.