Gold Coast, Australia, July 16 (The Conversation) Fossils are vital time capsules that offer insights into life forms from thousands to hundreds of millions of years ago. They allow scientists to track species evolution and understand ancient environments and climates. Additionally, fossils provide clues about the diets and migration patterns of long-extinct species, including human ancestors.
However, deciphering these details from fossilized remains is a complex endeavor. One prevalent method for examining fossils is micro-computerised tomography (micro-CT). This technique has been pivotal in discoveries such as the earliest evidence of bone cancer in humans, studying the brain imprints in early hominins, and analyzing ancient human teeth found outside Africa.
Yet, a new study published today in Radiocarbon reveals that, contrary to the common belief that micro-CT is non-destructive, it might actually impact fossil preservation, potentially erasing crucial internal information.
Preserving Precious Specimens
Fossils are naturally scarce and delicate. Researchers constantly weigh the need to study fossils against the risk of damage. It is crucial for palaeontologists and palaeoanthropologists to minimize potential harm to fossils and preserve them for the future, and technology plays a significant role in achieving this balance.
Micro-CT, akin to medical CT scans but on a smaller scale and with higher resolution, is ideal for examining small objects like fossils. It enables scientists to capture high-resolution 3D images and explore a fossil's internal structure without physically cutting into the specimen.
These scans also facilitate the creation of virtual fossil copies, allowing global access and significantly reducing physical handling risk, as scanned fossils can remain safe in museum collections.
Although widely regarded as non-destructive for lacking visible damaging effects, micro-CT might inadvertently harm the fossil.
How Does Micro-CT Imaging Work?
Micro-CT scanning utilizes X-rays and computer software to produce high-resolution images, detailing fossil specimens' internal structures. While most palaeontologists use commercial scanners, advanced studies might employ a synchrotron's powerful X-ray beams.
The X-rays penetrate the specimen and are detected on the opposite side, enabling a detailed understanding of its density, revealing internal shapes, tissue composition, and contamination.
This process generates a series of 2D images from multiple angles, which are then digitally processed to create a 3D virtual fossil replica.
X-rays Are Not Harmless
As a type of ionizing radiation, X-rays hold enough energy to dislodge electrons from atoms, a process known as ionization. In living tissues, ionizing radiation can damage cells and DNA, the extent of which depends on exposure duration and intensity. Medical X-rays and CT scans usually pose minimal risk due to controlled exposure levels.
Nevertheless, despite known effects on living cells, the impact of X-rays on fossils during micro-CT scanning has not been thoroughly explored until now.
What Did Our Study Find?
Using standard micro-CT settings, we scanned several modern and fossilized animal bones and teeth, measuring collagen content before and after scanning.
Collagen, crucial for various analyses like radiocarbon dating and stable isotope analysis (which can deduce extinct species' diets), depletes in fossils over time. Upon comparison, we observed two outcomes. First, radiocarbon dating was unaffected by micro-CT scanning, which is promising.
Unfortunately, we also found a significant collagen reduction, approximately 35% less in scanned samples compared to unscanned ones. This indicates that micro-CT scanning can seriously impact fossil collagen, potentially making some unsuitable for certain analyses, including radiocarbon dating.
What Now?
Previous research showed that micro-CT could artificially "age" fossils for electron spin resonance dating, used for fossils beyond the radiocarbon method's 50,000-year limit.
Our latest findings suggest that micro-CT scanning might significantly and irreversibly alter fossils and the information they contain.
Though it causes no visible damage, we posit that micro-CT should no longer be deemed non-destructive in this context. While indispensable in palaeontology and palaeoanthropology, micro-CT usage should be judicious to limit fossil X-ray exposure. Adopting guidelines to minimize damage and freely sharing data to avoid redundant scans could provide practical solutions. (The Conversation) SKS SCY
(Only the headline of this report may have been reworked by Editorji; the rest of the content is auto-generated from a syndicated feed.)
