I just finished the first book of fourth wing and I have opinions on how Tairneanach is portrayed in art. The book is not very descriptive of him except that he is massive.
I see lots of art drawing him like a scaled up version of what I think of as "horse dragons"- lithe, slim dragons heavily based on horse anatomy.
Personally I think Tairn, being huge and literally being named "Thunder", would have an overall denser look. (Details under the cut)
The feet are often shown as hand like claws, where they stand on their metatarsals, like cats. Tairn's size is described like a sauropod, IMO.
Sauropods developed thick toes surrounded in fat pads to support their massive weight. A similar evolution happened in Elephants, but they have a whole normal foot in there surrounded in fat pads.
I interpret Tairn's feet to be more like an Apatosaurus, but with longer claws and a thumb, meeting in the middle.
I also think he would be more tank-y like a T-rex. If you haven't seen a modern T-rex display, they aren't thin and upright anymore! They have stomach ribs, and stand very horizontal for balance. Like many large animals, they need support so gravity does not crush their organs, and they need to balance. Given how Tairn has four legs, I put less emphasis on the large, horizontal tail.
The broad head and neck are also from modern interpretations of Trex, as I assume a large carnivore would also need strong snapping jaw muscles and strength to lift prey/ his own massive noggin.
Many "horse dragon" interpretations also give them horse like chests, with connected rib cages.
But dragons fly! Flying things usually need a Keel bone to attach the wing muscles to so they have something to pull against. The bigger the bird, the more Keel is needed. See this California Condor- the ridge down its chest/ belly is the Keel bone.
See how it centers toward their wings to balance them? I think a dragon like Tairn would need a large, far back Keel. The large collar bones give mobility, and I move the ribs back to accommodate it. He is 4 legged though, so he still needs a scalpula. I think the wing muscles would go under the arms to connect to the keel and the wing joint would be closer to the neck to accommodate it- meaning he would fly a little forward centered, and balance with his long neck and big head instead of his tail as much.
lastly as far as nitpicks go, I see people give him a literal morningstar on the end of his tail. I think that they are just using the language they have to describe the most realistic and naturally occurring piece of dragon anatomy there is- a thagomizer! Or more specifically, the tail of a Glyptodont. They weren't reptiles, but their osteoderm club tails were similar to anklyosaurid and stegosaurid tails. (This one is missing its spikes)
I chose a more anklosaurid style clubbed spike tail that was still realistic as an inbetween to the different kinds of thagomizers.
Nothing is wrong with "horse dragons" of course, but it can be fun to look up more varied references for them I think! I think the horse dragon style works great for dragons the size of a clydsedale, but when you scale up, we should look at other large lizards! (Or dinosaurs, rather, as they weren't reptiles at all, and the dragons are also warm blooded :) )
ETA: Clean version cause reblog additions dont always show-
Maybe Tairn can't take Codagh on his own, but the combination of Tairn and Sgeayl could take him out easily. Plus they've alao got Andarna on their side.
