This is actually a problem https://www.buzzfeednews.com/article/natashaumer/dinosaur-animals
those artists tend to base their drawings on the fossils alone, while ignoring what the animal might have looked like with layers of fat and other things.
That's not true. They are modeled that way since they are reptiles and that's the fat proportion of reptiles.
But than again they are related to birds so we don't know
