Neutrons reveal blood-vessel traces inside Scotty’s fossilized rib

A fossilized rib from Scotty, the largest Tyrannosaurus rex skeleton discovered, is giving researchers an unusually detailed look at dinosaur biology—including what appears to be a network of preserved blood vessels inside the bone. The rib was broken during Scotty’s life, and the injury had begun to heal before the animal died. Scientists from the University of Regina used neutron imaging at the U.S. Department of Energy’s Oak Ridge National Laboratory to examine the fossil’s interior and create three-dimensional images without damaging it. According to the researchers, the rib contains mineralized structures consistent with blood vessels formed around the injury. Such soft-tissue preservation is rare because tissues like blood vessels typically decay before fossilization. The team says iron-rich blood associated with the injury and the salty marsh where Scotty died may have helped preserve the delicate structures. The discovery builds on work that began in 2020, when Jerit Mitchell, then an undergraduate at the University of Regina, identified evidence of blood vessels in the rib using micro-computed X-ray tomography at the Canadian Light Source. Further X-ray imaging and microscopy were used to study the fossilized tissue and the healing process at increasingly small scales. Neutron imaging provided another view. At Oak Ridge, researchers used the MARS instrument at the High Flux Isotope Reactor to image smaller bones, amber and fossilized dinosaur scales. They used the VENUS instrument at the Spallation Neutron Source to examine larger specimens, including Scotty’s rib. Neutrons are particularly sensitive to hydrogen and other light elements, while X-rays are generally more effective at revealing denser structures. The neutron results supported earlier findings from synchrotron radiation studies and added information about the fossil’s internal features, the researchers reported. The team plans to continue analyzing the data, examine more fossils and compare healing patterns across species. It also intends to investigate fossilized diseases and other abnormalities using combined neutron and X-ray techniques.