An international group of researchers have discovered that some dinosaurs shed their skin not like reptiles in one or a few goes, but in tiny flakes, just like mammals and modern birds do. They were able to work this out via the discovery that feathered dinosaurs also had dandruff.
The finding comes from 125-million-year-old specimens of feathered dinosaurs and early birds. The team used a powerful electron microscope to study the more minute features of these fossilized animals. They found that the dandruff cells are remarkably similar to what is seen today in birds. Their discovery is reported in the journal Nature Communications.
"The fossil cells are preserved with incredible detail – right down to the level of nanoscale keratin fibrils," lead author Dr Maria McNamara, from the University College Cork, said in a statement. "What's remarkable is that the fossil dandruff is almost identical to that in modern birds – even the spiral twisting of individual fibres is still visible."
The dandruff from the feathered dinosaurs – Microraptor, Beipiaosaurus, and Sinornithosaurus – was made of corneocytes, just like human dandruff. According to the researchers, this discovery helps us date the evolution of modern skin features to around the Middle Jurassic when these animals lived.
"There was a burst of evolution of feathered dinosaurs and birds at this time, and it's exciting to see evidence that the skin of early birds and dinosaurs was evolving rapidly in response to bearing feathers," Dr McNamara explained.
“It’s unusual to be able to study the skin of a dinosaur, and the fact this is dandruff proves the dinosaur was not shedding its whole skin like a modern lizard or snake but losing skin fragments from between its feathers,” co-author Professor Mike Benton, from the University of Bristol, added.
Modern birds have fatty corneocytes with loosely packed keratin. The way they are structured helps the birds cool down when flying for long stretches of time. The dinos' corneocytes, however, were packed with keratins. This suggests they didn’t get as hot as modern birds, likely because they were not adapted for powered flight, at least for long periods at a time.