Bringing 400-million-year-old fossilized armored worms to life – sciencedaily

An international team of scientists from the United States and Australia, led by Sarah Jacquet at the University of Missouri, have documented the discovery of two new species of fossilized armored worms in Australia – Lepidocoleus caliburnus and Lepidocoleus shurikenus – dating from around 400 million years ago. Then, using the micro-CT imaging capabilities of the central MU X-ray microanalysis facility, the researchers were able to develop one-of-a-kind digital 3D models of the species’ individual armor plates by virtually examining the armored skeletons of these ancient worms, called Macheridians.

Jacquet, an assistant professor of geological sciences at the MU College of Arts and Science, believes the study offers scientists a new way to study the workings of different biological shielding systems throughout the fossil record.

“Using micro-CT, we can virtually separate the individual components of the armor,” Jacquet said. “This allows us to see how he protected these worms until they unfortunately disappeared during one of the main extinction events in the fossil record. We are able to manipulate the virtual models to determine how the individual pieces of armor moved relative to each other., as well as determining the degree of overlap between them. “

At the time of their existence, these worms likely lived near coral reefs in shallow water on what is now land in Australia. The study identified these worms as having two overlapping armor systems – one running down the body’s skeleton and the other on both sides of the worm. Although no direct correlation has yet been established between these worms and any modern species, Jacquet believes his study may deepen our understanding of convergent evolution.

“Convergent evolution is where different, unrelated groups adapt similar characteristics,” Jacquet said. “While this armor is a rather unique adaptation, and one that clearly works well for particular environments and protects against particular predators, we see other similar adaptations in a few groups of unrelated animals, such as pangolins, bedbugs. and the centipedes. “

Jacquet said Lepidocoleus caliburnus is named after the famous sword “Excalibur” from Arthurian legend, and Lepidocoleus shurikenus is named for its resemblance to the outline of shuriken, the Japanese word for throwing stars. She said future plans for this work include using virtual models to study how these armor systems performed against different types of stressors, such as during a predator attack.

“Assembly of sclerites, articulation and protection system of Machaeridians of the Lower Devonian”, was published in Papers in paleontology. Other authors include Tara Selly and Jim Schiffbauer at MU, and Glenn Brock, who has dual appointments at Macquarie University in Australia and Northwest University in China.

Funding has been provided by grants from the National Science Foundation (EAR CAREER-1652351 and EAR / IF-1636643) and internal research development grants from Macquarie University. The content is the sole responsibility of the authors and does not necessarily represent the official views of the funding agencies.

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