>>28255172Feathers do not have the same function as fur. Fur keeps animals warm, feathers trap or keep away heat/cold. Feathers were mainly used as that and for display. Bird like flight-feathers didn't evolve until much later, and mainly for the raptor group. Not all was used for flight but more as a steering while running.
Yutyrannus have been found with feathers, covering literally the entire body down to the toes, and it's in the same group as rex. Feathers was hairlike, like an emu. Filamentous feathers. So no typical bird feathers.
A relative to triceratops actually has feathers, or more feather quills on the tail. Look up psitacosaurus. Feathers are actually a developed scale. And an ancestor to triceratops, stegosaurus and ankylosaurus was covered in hairlike feathers on the entire body except the tail that was fully scaly. It's called Kulindadromeus.
Some sort of feathers have been found in nearly all groups, so it means all dinosaurs could have had some sort of feathering. But it does not mean that all of them had birdlike feathers, as that is exclusive to some groups of theropods. But it could be quills, bristles, hairlike and the rest. Some dinosaurs feathers could be hardened back to scales, stopping the development of the scale into a feather.
Basically, ALL dinosaurs have a feathered ancestor.
