So, I've tried to put my reign of cringe on this account behind me, but certain people, *cough*Dan,*cough*Cactus, want me to address my old ways. So, yeah. I kinda….BSed a lot of stuff out of the way in terms of explaining tyrannosaur feathers. And I feel like I need to atone that. So, I present,
The Reasons Why Tyrannosaurs Lacked Extensive Feathering
First off, the scale impressions. While they are regarded as "not very substantial in terms of removing extensive feathering", none of them have clear borders, which would indicate feathering. It's far more of a reasonable assumption to believe that the scales indicate a majority of the integument being, well, scales.
Tyrannosaurs were big, some individuals reaching (possibly) 9. freaking. tons. And a dense, extensive coat of fluff doesn't exactly help when you're that big. Some argue "well, feathers are thermoregulatorily different from scales" but that doesn't really work that well when you're 35 feet long and weigh as much as an elephant and a half. Plus, feathers wouldn't help that much in thermoregulation because Hell Creek got surprisingly cold. But it's still the Maastrichtian and it also got very hot.
Yeah, the feathers wouldn't be useful for much. Maybe display, but the animal already has keratin crests and (likely)a throat sac You don't see predators being very flamboyant, and that's not going to change suddenly just because they're related to birds. They're not useful for thermoregulation, or display, or really anything. But it's not really likely it didn't have at least a couple sparse hairs somewhere, like on the shoulders or arms. Even whales are born with a few hairs on their snout, and elephants are born all fuzzy. And no, I'm not saying the chicks were all fluffy. The scales are most likely scales, not reticula. I know Paul Sereno claims to have a Tyrannosaurus skin impression that looks like "Plucked chicken skin", but it's not published and we can't really use it as an argument until so.
So, yeah. Sorry for the cringe I used to be. Bye.