What Alida Bailleul saw through the microscope made no sense. She was examining thin sections of fossilised skull from a young hadrosaur, a duck-billed, plant-eating beast that roamed what is now Montana 75m years ago, when she spotted features that made her draw a breath.
Bailleul was inspecting the fossils, from a collection at the Museum of the Rockies in Bozeman, Montana, to understand how dinosaur skulls developed. But what caught her eye should not, the textbooks said, be there. Embedded in calcified cartilage at the back of the skull were what appeared to be fossilised cells. Some contained tiny structures that resembled nuclei. In one was what looked like a clump of chromosomes, the threads that bear an organism’s DNA.
