large herbivores likely had no feathers due to their high body fat content rendering such adaptations redundant. we do know of at least some ornamentation in triceratops tho, mainly the fact that they had quills running along their tails. for animals like stegosaurus however, we’ve discovered enough skin imprints to determine that their close relatives (anklyosaurs) where featherless and instead had thick hide and osteoderms (natural armor plating) and it’s likely stegosaurus had similar