Its just the clean up code glitch, the games isnt removing dragon corpses correctly. Its a dead dragon skeleton thats respawned at the college. It just loaded the skin texture for it instead of the skeleton. Ive had it many times in whiterun with my pet dragon Dave.
Dave is a dragon I beat up a long time ago, but decided that he wanted to hang around. He comes out to meet me every time I enter whiterun, randomly appearing in town somewhere to say "Hi!". Some times he feels lonely because he has no-body around him.