Virtual 3D models of ammonite fossils show their muscles for first time

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Leslie Chernes et al.

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Researchers create highly detailed 3D model of ammonite fossil from 365 million years old jurassic By combining advanced imaging techniques, revealing intrinsic muscles that have never been seen before, according to one paper published Last month in the journal Geology. one more paper published Last month in the journal Papers in Paleontology the construction of 3D virtual models of armored plates from the fossil skeletons of two new species of ancient worms dated to 400 million years ago was reported.

The ammonite fossil used in the geology study was discovered in 1998 at the Clayden Pike Pit site in Gloucestershire, England, which consists mostly of poorly cemented sand, sandstone and limestone. Plenty of fragmented mollusk shells are scattered throughout the site, but this particular specimen was remarkably intact, with prolonged exposure through scavenging, shell encrustation, or being removed and re-deposited from elsewhere. Didn’t show any sign. The fossil is currently kept at the National Museum of Wales, Cardiff.


“When I found the fossil, I knew right away that it was something special,” Co-author Neville Hollingsworth said, Public Interaction Manager in the Council of Science and Technology Facilities. “The shell split in two and the body of the fossil was revealed to look like soft tissues. It is wonderful to finally know what these are through the use of state-of-the-art imaging techniques.”

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First, the team photographed the inner mold and subjected the fossil to scanning electron microscopy and energy-dispersive X-ray spectroscopy. Then the researchers combined two powerful and complementary imaging techniques.

Neutron tomography is very similar to X-ray imaging methods except that it is not sensitive to the density of the material. So some of the things that are easily visible with neutron imaging can be challenging or impossible to see with X-ray imaging (and vice versa). The team collected more than 1,800 30-second projections via neutron tomography and used computer software to reconstruct them into 2D slices.

X-ray microtomography Involves using X-rays to create cross-sections of a physical object that can be used to reconstruct a virtual 3D model without destroying the original object. With this method, the team captured 6,000 projections, which were reconstructed into a single 3D image. X-ray microtomography data is particularly useful for revealing important details about the inner and outer shell structure.

Both data sets were imported into specialized software to produce a combined 3D model. The X-ray data, when aligned with neutron tomography data, result in remarkably detailed false-color 3D renderings of the fossil.

“Despite being discovered 20 years ago, scientists are opposed to the destructive option of biting [the fossil] except to see what’s inside,” Co-author Alan Spencer said of Imperial College London. He continued:

Although it would have been much faster, it would have risked permanent loss of some information. Instead, we waited until non-destructive technology took hold – as it is now. This allowed us to understand these internal structures without causing any damage to this unique and rare fossil. This result is a testament to both the patience shown and the amazing technological advances going on in paleontology.

Fossil ammonite block.
Leslie Chernes et al., 2021

Paleontologists usually rely on modern-day genus nautilus As a model for ancient ammonoid fossils, which bear at least a superficial resemblance to their Jurassic forebears. But this new 3D model showing muscle and soft tissue suggests that those similarities may just be shell-deep, and that ammonites may have more in common, evolutionarily speaking, with today’s colloid subgroup, which includes squid, octopus and Contains cuttlefish.

3D virtual model of Jurassic-era ammonite fossil shows internal muscles never seen before.
Leslie Chernes et al.

“Preservation of soft parts in ammonites is exceptionally rare, even compared to fossils of closely related animals such as squid,” Co-author Leslie Chernosso said of Cardiff University. “We found evidence for muscles that don’t exist nautilus, which provided important new insights into the anatomy and functional morphology of ammonites.”

Most notably, it floats using ammonite jet propulsion, in which water is expelled through a tube or funnel (hyponome) located near the opening of the body’s chamber. Among other findings, the researchers observed muscles extending from the body of the ammonite, which they speculate the animal used to propel itself further back in its shell to escape predators. (Ammoniums did not have the ink-sac-like protection common to octopuses, squid, and cuttlefish.)

“It took more than 20 years of patient work and testing of new non-destructive fossil scanning techniques until we hit on a combination that could be used for this rare specimen.” co-author Russell Garwood said of the University of Manchester, who is also a scientific associate at the Museum of Natural History. “This highlights both: the importance of our national museum collections providing access to these important specimens in a sustainable manner and the pace of technological advances within paleontology in recent years.”

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