"This is the first time birdlike feathers have been found in dinosaurs that are not closely related to birds," said Darla Zelenitsky, a paleontologist at the University of Calgary in Canada, who was not involved in the research. "This unexpectedly reveals that such feathers would likely have been present in most groups of dinosaurs," Zelenitsky told Live Science in an email.
Steve Brusatte, a paleontologist at the University of Edinburgh in Scotland, agreed that feathers probably existed in the common ancestor of all dinosaurs. The idea is not a new one, he said; two other fossils of plant-eating dinosaurs found in China had simple, filamentlike feathers, but it was debatable whether these were related to bird feathers, or evolved independently. Now, this new evidence "seals the deal that feathers were also present in plant-eating dinosaurs," Brusatte told Live Science.
As for the fossil scales, they resemble modern birds' scales, which are actually aborted feathers, the researchers said. In chickens, for example, genes in the skin control the development of feathers. If these genes are modified, the chicken will sprout feathers on its legs, like that of an English chicken. Perhaps primitive dinosaurs had already developed this genetic mechanism of preventing feathers from developing in certain parts of their bodies, Godefroit said.