Photographs of cartilage cells from skull of Hypacrosaurus nestlings.
On the left, two cells at the end of cell division are seen, with material consistent with condensed nuclei. In the center, a higher magnification image of another cell shows chromosomes. On the right is an isolated dinosaur cartilage cell that reacts with the DNA stain Propidium iodide (red dot, inside the cell). This stain suggests there is still endogenous dinosaur DNA in this 75 million-year-old cartilage cell. Photo credit: Alida Bailleul and Wenxia Zheng