Dinosaur fossils, it was long thought, are simple objects. The fossilization process leaves the overall shape of a dinosaur's bones intact, but all the microscopic structures inside them — the blood cells, connective fibers, and other sorts of soft tissue — inevitably decay over time. The photo above, from a new study published today in Nature Communications and led by Sergio Bertazzo of Imperial College London, shows an extremely zoomed-in view of a 75-million-year-old theropod claw, taken from the London Natural History Museum's collection. When researchers scraped tiny pieces off the fossil and looked at them under an electron microscope,...