Question: How did you figure out that dinosaurs had dandruff ?

Maria McNamara answered on 12 Nov 2019:

My colleagues and I found tiny fragments of skin (each < 1 mm in size) trapped in between (and on) fossil feathers on the feathered dinosaurs Microraptor, Sinornithosaurus and on the ancient bird Confuciusornis. We found the fragments when we were studying the feathers with electron microscopes and realised pretty quickly that only the outer layer of the skin (made of cells called corneocytes) was preserved. That's what dandruff is made of!