[teruakohatu]

"billed dinosaurs, horned dinosaurs and armoured dinosaurs did not have feathers because we have lots of skin impressions of these animals that clearly show they had scaly coverings" [1]

There is no evidence for example that protoceratops, whose skulls are pictured in the article, had feathers.

Non-avian theropods had feathers, but even then were not necessarily covered with them, it could be a few feathers under the arms. We are talking about species over a 200 million year time period.

[1] https://www.nhm.ac.uk/discover/news/2020/march/the-first-din...