Does a dilophosaurus fossil that holds the image of what looks like feathers prove that dinosaur had feathers, or is there another explanation that might account for their appearance?
Tony Martin is an ichnologist, he studies the tracks and traces that dinosaurs left behind to fill in details about what we know about them. In response to a question in this post, about what he thought of the "feathered" dilophosaurus fossil, Martin explains how — though a fossil may look like it has the impression of left behind feathers — appearances may be deceiving:
No feathers. I've looked at that same specimen (AC 1/7) of a "sitting dinosaur" trace fossil with a colleague (Emma Rainforth), and we concluded the "feather impressions" were wrinkle marks in the mud made by the dinosaur shifting its position and otherwise moving. To imagine how these could be made, think how you might wrinkle a plastic wrap by running your finger across its surface. I really wanted these to be feather impressions, too, but hey, SCIENCE.
Image: Dilophosaurus fossil at the Royal Ontario Museum / Eduard Solà Vázquez