CT scanner captures woolly mammoth’s entire tusk
For the first time, researchers have successfully created CT images of a whole woolly mammoth tusk, according to a new “Images in Radiology” article published in the journal Radiology. Researchers were able to get a full scan of the tusk in its entirety — or in its entirety — using a newer clinical CT scanner. The new technology enables large-scale imaging without the need for multiple partial scans.
“Working with precious fossils is challenging because it’s important not to destroy or damage the specimen,” said the paper’s senior author Tilo Niemann, MD, chief of CT, and cardiac and thoracic radiology in the Department of Radiology. of Kantonsspital Baden in Baden, Switzerland. “Even if several imaging techniques exist to evaluate the internal structure, it has not been possible to scan in an entire tusk without the need for fragmentation or at least multiple scans which then had to be painstakingly mounted. “
The extinct woolly mammoth (Mammuthus primigenius) was the size of a modern-day African elephant and lived throughout Eurasia and North America. Most woolly mammoths became extinct with the end of the last ice age, and the last ones lived about 6000 years ago. They belong to the order Proboscidea, which includes today’s elephants, as well as other extinct mammoths, mastodons, and gomphotheres.
Mammoths were covered in fur and had small ears and a small tail to prevent frostbite. They also had tusks that they used to scrape bark from trees, dig the ground for food, and fight. The tusks of proboscideans have enabled researchers to determine the age and identification of specific life-changing events based on annual growth rate analysis.
Newer CT scanners have larger portals, the ring or cylinder in which a patient, or in this case the tusk, is placed. The introduction of larger portals now provides the ability to scan larger objects that were previously not possible, noted Dr. Niemann up.
The tusk that the researchers examined was found in central Switzerland and excavated by the heritage and archeology office of the canton of Zug. The tusk is a total of 206 centimeters (cm) long – almost 7 feet. It has a basal (measurement at the base) diameter of 16 cm – just over 6 inches. The total object diameter — taking into account the helical or spiral curvature — is 80 cm, or just over 2.5 feet.
Tusks are usually made up of two types of material: cementum, a bone-like substance, and dentin, which lies beneath the cementum and makes up most of the tusk’s mass. The tusks of mammoths are internally structured by annual increases in dentin attachment which, viewed in longitudinal section (as opposed to cross section), resemble conical cups stacked on top of each other. The first “cone” a mammoth makes forms the tip of the tusk, while the cone at the base of the tusk is the most recent, just before the animal’s death. The cones between them are formed during the mammoth’s lifetime.
Using the larger CT scanner, researchers, in collaboration with the Institute of Evolutionary Medicine, University of Zurich, were able to capture a clear image of the interior of the entire tusk.
“It was fascinating to see the internal structure of the mammoth tusk,” said Dr. Niemann.
The researchers found a total of 32 cones, resulting in a minimum age of 32 years at the time of death. Although the mammoth tusk is well preserved, it is missing the tip, so the estimate obtained is slightly below the animal’s actual age at the time of death.
“Our mammoth had died at the age of about 32, about 17,000 years ago,” said Dr. Niemann.
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Patrick Eppenberger et al, CT-based age estimation of a mammoth tusk, Radiology (2022). DOI: 10.1148/radiol.220265
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