How Scotty, the world's largest Tyrannosaurus, died has been revealed. The cause of death was identified not by a paleontologist or a forensic scientist, but by a particle physicist who studies the fundamental particles that make up nature and the forces between them.
Oak Ridge National Laboratory (ORNL) under the U.S. Department of Energy said on the 2nd that "physicists used neutron imaging technology to look inside the bones of Scotty, a Tyrannosaurus that fossilized 66 million years ago, and produced a 3D (three-dimensional) image showing blood vessels without damaging soft tissues."
Scotty was first discovered in 1991 in the Frenchman River Valley in Saskatchewan, Canada. The name came from the Scotch whisky drunk to celebrate the excavation. By 2011, 20 years after the first excavation, 65% of the full skeleton had been identified. Scotty is the largest Tyrannosaurus fossil ever found. The body length and height are 13 meters and 4.5 meters, respectively, and the body weight in life is estimated at about 8.8 tons.
◇ Research began with an undergraduate's CT scan 6 years ago
Mauricio Barbi, a professor in the Department of Physics at the University of Regina in Canada who led this research, said, "Scotty's rib fossil had an extensive network of mineralized blood vessels that had not been observed before," adding, "It feels like winning the lottery."
The research team reconstructed Scotty's final moments as follows. Scotty hunted a Triceratops, a dinosaur with three horns on its head, while alive. During the hunt, another Triceratops rammed from the side with its horn and broke a rib. A healing process for the fracture began in Scotty's body. Iron-rich blood flowed into the damaged area and formed the blood vessels confirmed this time.
Scotty died before the ribs fully knit and remained as the fossil we see today. Still, because death came in a salt-rich wetland along with iron-rich blood, it was possible to tell how death occurred. Wetland soils are always submerged, so oxygen from the air cannot easily penetrate inside. Being buried in such a place reduces oxygen and slows decay. As a result, soft tissues prone to decay remained in the bone.
Jerit Mitchell, a doctoral researcher in Barbi's lab, found traces of blood vessels in 2020, when an undergraduate, in a computed tomography (CT) scan of Scotty's rib. CT is a method of assembling hundreds of cross-sectional images of tissue taken by passing X-rays through from multiple angles to view the inside of the body in three dimensions.
The team also used the synchrotron, the University of Saskatchewan's circular particle accelerator, to analyze Scotty. A particle accelerator is a device that accelerates charged particles to near the speed of light by pulling them with electrodes of opposite charge. Among them, the university's synchrotron light source accelerates electrons to the speed of light. When the accelerated electrons change direction, X-rays emitted tangentially can be used to observe the interior of matter. X-rays are advantageous for analyzing heavy elements. X-rays interact with electrons inside atoms, and atoms with larger atomic numbers, like iron, copper and lead, have more electrons.
◇ Neutrons from a particle accelerator provide final confirmation
After identifying fossilized blood vessels with X-rays, the researchers conducted neutron analysis with a particle accelerator at Oak Ridge to find more clues. An atom consists of a nucleus at the center and electrons orbiting it. The nucleus contains protons, which carry a positive charge, and neutrons, which carry no charge. Electrons carry a negative charge. Because neutrons have no charge, they can penetrate deep into matter.
The neutrons that analyzed Scotty's rib came from the VENUS beamline at Oak Ridge National Laboratory. Neutrons have no electric charge and cannot be accelerated by an electric field. Instead, VENUS accelerates protons and smashes them into metal, causing neutrons to spall out. These neutrons were gathered and sent into the rib.
Neutrons not only reconfirmed the vessels found by the synchrotron light source, but also produced clear images of traces of soft tissue that were difficult to confirm with X-rays. That is because neutrons are particularly sensitive to hydrogen atoms in moisture-rich soft tissues. The researchers explained that this is like how X-rays in hospitals show dense structures such as bones, while magnetic resonance imaging (MRI) shows soft tissues such as muscles clearly. MRI produces images by exploiting the resonance of hydrogen nuclei in water molecules (H₂O) within a magnetic field.
The team said it plans to analyze a wider variety of fossils with particle accelerators going forward. By combining neutron imaging and X-ray techniques, they will look for traces of disease or injury left in fossils and compare them with modern species. Dinosaur research is taking a leap forward with the new tool of particle accelerators.
References
Oak Ridge National Laboratory (2026), https://www.ornl.gov/news/ornl-neutron-bone-imaging-brings-t-rex-life