March 28, 2024

Remarkable Jurassic Fossil Reveals 165-Million-Year-Old Ammonite Muscles in 3D

3D model of an ammonite. Credit: Lesley Cherns et al

An exceptionally maintained Jurassic fossil from Gloucestershire in the UK has actually provided brand-new insights into the inner operations of ammonites, according to a research study released recently in the journal Geology.
Researchers produced a detailed 3D computer system restoration from combined neutron and X-ray pictures of the special 165-million-year-old fossil ammonite, which permitted them to describe its internal muscles.
Ammonites are a renowned extinct group that grew in ancient oceans hundreds of countless years back, when the dinosaurs ruled on land. They went extinct at the end of the Cretaceous duration, around 66 million years back.

Ammonites are amongst the most typical fossils worldwide, but almost everything we know about them is based upon their tough shells. The modern-day animal Nautilus has actually generally been utilized as a design for rebuilding the biology of ammonites, but the study suggests the 2 groups may not be as comparable as previously believed. This is exposed by the muscles and organs within the ammonite body, visualized in 3 dimensions for the very first time in the brand-new fossil.
Paired muscles extending from the body mass are believed to have been utilized to withdraw the animal deep into the body chamber for protection. This would have been an important anti-predator adjustment in ammonites, which did not have other defensive functions, such as an ink sac, seen in contemporary family members like cuttlefish, squid, and octopus.
The arrangement of the muscles suggests ammonites swam by expelling water through the tube-like siphon, called a hyponome, next to the opening to the body chamber. This kind of swimming is called jet propulsion, and it is utilized by a large range of living animals, consisting of cephalopods (squid, octopus, cuttlefish, and Nautilus), the larger group to which ammonites belong.
Lead author Dr. Lesley Cherns, Honorary Research Fellow at Cardiff University, said, “Preservation of soft parts is exceptionally uncommon in ammonites, even in comparison to fossils of closely associated animals like squid. We found proof for muscles that are not present in Nautilus, which offered essential new insights into the anatomy and practical morphology of ammonites.”
The fossil was found more than 20 years earlier and has actually been studied on and off ever since, however just current technological innovations allowed its internal structures to be visualized. The research study group used a combination of advanced methods, including instruments at ISIS Neutron and Muon Source at Harwell and the Henry Moseley X-ray Imaging Facility at the University of Manchester, to digitally reconstruct the within of a “virtual ammonite.”
Co-author Dr. Alan Spencer, Senior Strategic Teaching Fellow at Imperial College London and Scientific Associate at the Natural History Museum, said, “We combined high-resolution X-ray imaging with high-contrast neutron imaging to study the interior of the fossil in 3D without harming it. This permitted us to picture internal pulps that had withstood all previous efforts to describe them. Its a significant development in ammonite palaeobiology.”
Dr. Imran Rahman, a co-author and Principal Researcher at the Natural History Museum, added, “Our research study recommends that combining different imaging techniques can be crucial for investigating the soft tissues of three-dimensional fossils. This opens up a range of exciting possibilities for studying the internal structure of incredibly maintained specimens. We will be busy!”
Co-author Dr. Russell Garwood, a senior lecturer at the University of Manchester and Scientific Associate at the Natural History Museum stated, “It has taken over 20 years of client work and testing of brand-new non-destructive fossil scanning strategies, until we hit upon a mix that might be utilized for this unusual specimen. This highlights both: the value of our national museum collections which permanently hold and provide access to these crucial specimens; and the speed of technological advances within paleontology over recent years.”
Dr. Genoveva Burca, neutron imaging and diffraction scientist at the ISIS Neutron and Muon spallation source and among the co-authors said, “The outcome of this exciting project reveals the advantages of an interdisciplinary and imaginative technique, the big potential of neutron imaging applications and usage of complementary non-destructive techniques which can a be a real game changer in lots of areas of scientific investigations including Palaeontology expanding its horizon and taking the research study in this field to an entire new level.”
Dr. Neville Hollingworth, a co-author and Public Engagement Manager at the Science and Technology Facilities Council, discovered the fossil. He added, “When I found the fossil, I instantly understood it was something unique. The shell split in two and the body of the fossil fell out revealing what appeared like soft tissues. It is terrific to lastly understand what these are though using cutting edge imaging techniques.”
Reference: “Correlative tomography of an incredibly preserved Jurassic ammonite implies hyponome-propelled swimming” by Lesley Cherns, Alan R.T. Spencer, Imran A. Rahman, Russell J. Garwood, Christopher Reedman, Genoveva Burca, Martin J. Turner, Neville T.J. Hollingworth and Jason Hilton, 7 December 2021,. DOI: 10.1130/ G49551.1.
This work was brought out by a group of scientists from Cardiff University, Imperial College London, the Natural History Museum, University of Manchester, ISIS Neutron and Muon Source, the Science and Technology Facilities Council and the University of Birmingham.
The fossil is housed at the National Museum Wales.

. Beautifully preserved fossil ammonite collected from 165-million-year-old Jurassic website in Gloucestershire, UK;
3D reconstruction of combined neutron and X-ray images of fossil programs internal muscles never ever formerly seen in ammonites;
Muscles utilized to withdraw body into the shell for security;
Ammonites swam through jet propulsion, like modern-day octopus and squid.

3D design of an ammonite. Beautifully preserved fossil ammonite collected from 165-million-year-old Jurassic website in Gloucestershire, UK;
Ammonites are among the most common fossils worldwide, however almost whatever we understand about them is based on their hard shells. The modern animal Nautilus has actually generally been used as a model for rebuilding the biology of ammonites, however the research study recommends the 2 groups might not be as comparable as previously thought. Its a major advancement in ammonite palaeobiology.”