Lead author Dr Lesley Cherns, Honorary Research Fellow from Cardiff University’s School of Earth and Environmental Sciences, says: But, despite Nautilus being a shelled cephalopod like the ammonite, it seems ammonite biology has more in common with their shell-less relatives, squids and octopuses. Until now, because ammonite soft tissues are so rarely preserved, scientists have used the modern cephalopod Nautilus as a body plan for reconstructing ammonite biology. This would have been a crucial defence mechanism as ammonites lacked defensive features such as the ink sac found in squid, and the plate-like hood of Nautilus. The images have also revealed paired muscles that would have allowed the ammonite to protect itself from predators by retracting itself deep into its shell. This sort of jet propulsion is also used today by modern cephalopods like squids and octopi. The arrangement and relative strength of muscles reveal that the ammonite swam by expelling water through a muscular tube-like funnel called a hyponome. By combining these results with neutron imaging on the IMAT instrument at ISIS, the researchers were able to gain previously unattainable insights into the ammonite’s inner workings. Previous investigations into ammonite anatomy have relied on X-ray techniques that are unable to determine the structure of the soft tissues. On the rare occasions where soft parts have been found, they are mostly flattened. In almost all cases, it’s only the hard shell, not the soft parts, preserved in fossil ammonites. However, important details of the living animal were largely still a mystery. Their hard shells made of calcium carbonate preserve well. Finding ammonites with the fossilised remains of soft parts is virtually unknown in the fossil record.ĭr Imran Rahman, a principal researcher at the National History Museum and co-author, says:Īmmonites are an iconic extinct group of marine animals renowned for their rich fossil record that stretches back hundreds of millions of years. However, almost everything we know so far about ammonites is based on their hard shells, which are more easily preserved than soft tissues. They are excellent ‘index fossils’ for dating rock, allowing palaeontologists to link layers of rock with a specific ammonite species of genus and thus deduce the date the layer was deposited. They were so prolific in the ancient oceans and lived throughout the reign of the dinosaurs that they are one of the most common fossils. The complementary non-destructive investigations will play a major role in other future discoveries and the advancement of science.Īmmonites ranged in size from less than a centimetre to two metres in diameter. I’m thrilled that thanks to neutrons the paleontological research will enter a new era and the fossils will reveal more and more of their secrets.
![ammonite shell ammonite shell](https://ae01.alicdn.com/kf/HTB1oktaIXXXXXXzXXXXq6xXFXXXR/274g-1-Pair-Half-Cut-Ammonite-Shell-Jurrassic-Fossil-Specimen.jpg)
The correlative neutron and X-ray tomography allowed us to visualise for the very first time the internal soft parts of ammonites. This has shed new light on how the cephalopod mollusc was able to propel itself through the oceans and defend itself from predators.ĭr Genoveva Burca, neutron imaging and diffraction scientist at ISIS, who initiated the collaboration for the project a few years ago and one of the co-authors says: The new images captured at Science and Technology Facilities Council’s (STFC) ISIS Neutron and Muon Source (ISIS) have allowed the team to analyse the muscles and organs of an ammonite for the very first time. Closely related to modern squids, these marine creatures dominated the ancient oceans from 400 million years ago until the mass extinction event that ended the reign of the dinosaurs 66 million years ago.
![ammonite shell ammonite shell](https://ae01.alicdn.com/kf/HTB1MQIGHVXXXXcBXFXXq6xXFXXX7/257g-1-Pair-Half-Cut-Ammonite-Shell-Jurrassic-Fossil-Specimen.jpg)
While not being the most glamorous members of the fossil record, ammonites are among the most ubiquitous inhabitants of the prehistoric world. ammonites swam using jet propulsion, like modern octopus and squid.
![ammonite shell ammonite shell](https://ae01.alicdn.com/kf/HTB1huEiXviSBuNkSnhJq6zDcpXa3/Beautiful-Ammonite-Shell-Fossil-Disc-Madagascar-whole-ammonite-fossil-connected-together-not-broken-ones-with-shelf.jpg)
it shows muscles that were used to retract the body into the shell for protection.3-D reconstruction of combined neutron and x-ray images of fossil shows internal muscles never previously seen in ammonites.the exceptionally-well preserved ammonite fossil was found in a 165-million-year-old Jurassic site in Gloucestershire, UK.The three-dimensional images shed new light on creatures that thrived in the oceans for 370 million years and reveal that, like their modern squid cousins, ammonites were marine jet-setters. Scientists have, for the first time, been able to reveal details of soft tissues preserved in one of the most instantly recognisable fossils: the ammonite.