This is probably a stupid question, but did large herbivores like Triceratops and Diplodicus have feathers? I can accept the bird-like dinos with feathers, but I'm having a really hard time imagining feathered ceratopsians.
THERE IS NO SUCH THING AS A STUPID QUESTION :)
It’s all about phylogenetic bracketing (looking at the possible distribution of a trait based on the trait’s prevalence in relatives).
So feathers are an ancestral trait in Dinosauria - making it more likely that the more basal (meaning: more closely related to the most recent common ancestor of all dinosaurs) dinosaurs all had some sort of protofeather covering.
However, some later groups did lose their feathers. We know this because we do have scaly skin from some dinosaurs - hadrosaurs, titanosaurs, Carnotaurus, etc.
So while all dinosaurs (that we haven’t found scale impressions of) could have had feathers, for some it’s much more likely than others.
So then, for the more derived (ie, less closely related to the ancestral dinosaur) dinosaurs that aren’t theropods - who got more fluffy as they evolved - we have to do some guesswork, based on scaly and feathered fossil tracking.
For ceratopsians, one fairly basal form - Psittacosaurus - was found with quills on the tail; though it was scaly everywhere else on the body. Still, it was derived for a dinosaur. However, there aren’t any other ceratopsians found with quill impressions - it’s just Psittacosaurus. Meanwhile, Triceratops, Chasmosaurus, and Centrosaurus - all later ceratopsians - have been found with scales. So, it’s reasonable to suppose that early members of the group - such as Leptoceratops - may have had similar quills as Psittacosaurus, it’s highly unlikely that the later forms did as well (though, the skin impression in these animals is not from the tail itself, but other portions of the body - so putting quills on their tails, while unlikely, is not necessarily incorrect).
Now, for sauropods, titanosaurus (the most derived group) have been found with scaly skin impressions, making it unlikely that they had feathers. Other genera of saurpods have also been found with scales on portions of their body, such as Diplodocus, Mamenchisaurus, and Camarosaurus, indicating that in these later forms of Sauropodomorpha, any of the ancestral fluff was probably lost, at least in adulthood.
Scales have also been found in adults of Thyreophorans (stegosaurs and ankylosaurs) - specifically, Stegosaurus, Hesperosaurus, Gigantspinosaurus, and Scelidosaurus, among others, indicating that these lost the floof as well.
Hadrosaurs are probably the best known to be scaly of all of these - many scale impressions have been found throughout the group over most of the body, indicating that they lost any protofeathers altogether in adulthood. Same goes for the titanosaurus.
However, things to note:
- For a lot of these scale impressions, we only have a limited portion of the body known - for others we have a lot - so while all of these animals have confirmed scales, some may still have had small vestigial tufts, sort of like elephant fur. I say this because feathers don’t fossilize very well at all - they’re delicate structures that typically decompose before they have a chance to do so, meaning that we we are most likely underestimating how many things had protofeathers. However, for some groups this is especially unlikely, like in hadrosaurs, given that we have their skin very well preserved. It really depends on how much we know about the scales of the animal, and where we’ve found them on the animal in question.
- These impressions come from adults almost entirely across the board, meaning, infants may have had protofeathers that they then lost in adulthood - which they could have kept for added insulation, especially since the added temperature control they would get with larger size was not present when infants
TL;DR: WHEN IT COMES TO NOT-THEROPODS, we do know of quite a few dinosaurs that decidedly did not have feathers. Others we know had scales, but we don’t know if their entire body was covered. The more closely related to the ancestral dinosaur something is, the more likely it still has floof.
- Not-sauropod Sauropodomorphs we have no idea and given their basal position probably had protofeathers; Sauropods probably did not have floof; definitely did not in the Titanosaurs
- Ornithischians not in more derived groups - such as Heterodontosaurs - definitely had floof
- Hadrosaurs definitely did not
- Early ceratopsians may have had quills only on the tail; later forms unlikely
- Stegosaurs & ankylosaurs unlikely to have extensive floof
- Possible that anything (except titanosaurs and hadrosaurs) had vestigial tufts like elephants; feathers don’t fossilize well
- All of this is about adults; we don’t know about the infants
holy crap a lot of sources coming hold onto your butts; under the cut cause it was INTENSE