Ringer ArchedCory, who writes for our friends at Heirs of Durin, has put together this excellent article dissecting (though not literally) the anatomy of Smaug, drawing parallels with creatures from our real world. The particular shape of the head, what might have inspired it? What of the teeth? The eyes? Or the skin texture?
A couple of excerpts:
At first glance Smaug’s head bears a strong resemblance to Tyrannosaurus rex. Apart from the fact we only know skulls of T.rex and not the detailed shape of muscles and skin covering it up, there are still differences that can be noticed: the ratio between length and height seems to be slightly different, with Smaug’s head being longer and narrower. The nostrils are a bit further back and the teeth are shorter and sharper.
With his rather long snout, sharp teeth and floppy throat he could also be in a way compared to crocodiles. Considering T.rex and crocodiles have quite a different internal anatomy (dinosaurs and crocodiles systematically speaking are not closely related) it would be interesting to see Smaug’s skull. We do know that Weta likes to build their CGI characters layer by layer from skeleton up, so I hope at one point in the future they will give us Smaug’s skull!
When it comes to teeth the animators have obviously studied crocodiles or Komodo dragons (Varanus komodoensis) very closely. Just like Smaug, they are also carnivorous reptiles. As such they have very typical teeth. Unlike mammals with their distinct differentiation in incisors, canines, premolars and molars, teeth in reptile jaws are a lot simpler, and more or less all look the same.
They only differ in size, but most of the time they are conically shaped. Back to the crocodiles/Komodo dragons: Their teeth are long and exceptionally sharp, after all they want to score kills with them. And Smaug’s teeth are very close to that concept.