Look at the leg of almost any bird and you’ll see feathers covering the thigh but scales covering everything from the ‘knee’ downwards. There are a couple of exceptions—some birds of prey look like they’re wearing baggy trousers and golden eagles have fluffy foot feathers for insulation. But for the most part, living birds have naked lower legs.

It wasn’t always this way. We know that birds evolved from small two-legged, meat-eating dinosaurs that were covered in simple fuzzy feathers. Those on their arms eventually became longer and flatter, evolving from hollow tubes into flat asymmetrical vanes. They transformed from “dino-fuzz” into flight feathers, and their arms transformed into wings.

Meanwhile, it’s tempting to think that the feathers on their