Stegosaurus stenops
The elephant-sized, narrow-faced stegosaur, decked out in lurid display, "warns" his predators to back off, lest they get a bone-gouging surprise.
A household name of a dinosaur, Stegosaurus needs no introduction, but the use of its iconic plates has been the subject of many theories, from thermoregulation to sexual display (the related Hesperosaurus seems to have two separate morphs differed by plate shape, which might lean to that). Some however have speculated a form of aposematism, horridly abstract colours and patterns that can be found on many defensive animals, from poison dart frogs to coral snakes and lowland streaked tenrecs, used to deter predators from ever dangerously touching them.
Even mammals have something to say with their colour. This lowland streaked tenrec is piled in aposematic patterns to warn predators from getting spines in their mouths. Source I sadly couldn't find.
Stegosaurus was a slow tank which had similar deadly defences. Such an idea was somewhat explored in the documentary Walking With Dinosaurs, where a Stegosaurus flushed blood into its plates to display a red colour to intimidate an Allosaurus, though this is now inaccurate, since the plates of stegosaurs are now known to have been covered in sheath and not skin, as shown by preserved Hesperosaurus skin impressions. Here, Stegosaurus stenops bears aposematic patterns across its body. On the plates, they culminate in humongous eyespots that could even intimidatingly render the Stegosaurus a wide, multi-eyed monster to its predators, drawing away from the insignificant head. There are also some ornithsichian filaments/protofeathers behind the beak, on the throat (maybe as little, prickly, defensive quills), the tail, and as eyelashes (albeit hard to see here) like those of modern birds, which could protect the dinosaur’s eyes from dust in its semi-arid environment. Some smaller ornithischian fossils of great preservevation have been found with fluff like this, so it’s not implausible that they’re bigger cousins would’ve had some too. I’ll actually see the best-preserved narrow-faced stegosaur, "Sophie", in a few days.
Sophie and her ghost.
