CT scanning helps reveal path from rotten fish to fossil

Scientists have found that X-Ray scanning reveals secrets of fossil formation without disturbing the decay of buried carcasses

A new study published in Palaeontology has confirmed that X-ray computed tomography (XCT scanning) can be used to monitor decomposing organisms without altering the natural decay process – a vital step for understanding how fossils form.

A research team from the University of Birmingham entombed dead zebrafish within sediment to test whether repeatedly zapping decaying specimens with X-rays would change how they decompose. Their findings suggest this non-invasive imaging technique allows scientists to watch decay happen in real-time without disturbing the process - unlike traditional methods that require digging up and potentially damaging specimens.

"It's like getting a snapshot of nature's natural recycling program," said Dr Iacopo Cavicchini, lead author on the study. "Previous methods were like trying to observe a smelly bag of goop by digging it up – it's very difficult and you inevitably alter what you're trying to study."

The research addresses a significant challenge in taphonomy – the study of how organisms decay and become fossils. Traditional decay experiments require researchers to unearth specimens to observe them, causing artificial damage or disarticulation that can mess with the results. In order to test if CT scanning could be used in their experiments, the research team wanted to know whether X-ray exposure would interfere with the bacteria that drive decay.

Their findings showed that the microbes continued to decay the carcass, unimpeded by periodic exposure to X rays — proving the technique serves as a crucial stepping stone toward more sophisticated non-invasive decay experiments that better mimic natural conditions of fossil formation.

"This study validates an important non-destructive tool for palaeontologists and forensic scientists alike," said Dr Thomas Clements, who supervised the project, now based at Friedrich-Alexander-Universität Erlangen-Nürnberg. "We can now watch decay within sediments, providing unprecedented insights into the processes that ultimately create fossils."

Perhaps the most explosive finding in this study was the ability to witness—in high definition—the dramatic buildup of decomposition gases inside the fish carcasses before they eventually pop. "We essentially created decaying fish fart surveillance," said Dr Cavicchini, "which sounds silly until you realise it's providing crucial insights into how internal cavities collapse during fossilisation"

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