Okay so I was doing Molag Bal's quest (sacrificing a priest of Boethiah? heresy, I say!). So, after dropping off a mountain of loot at Breezehome, I took a carraige to Solitude with plans to fast travel to the Shrine of Meridia, my nearest discovered location to where the priest was. So, I arrive at the shrine thinking "maybe this will cause a dragon to spawn." Sure enough, I hear that roaring and see a dragon flying around. So I draw my bow and move away from the trees to try and get a shot at it, and what do I see? A dead dragon! The airborne dragon (possibly Alduin?) circled around a bit, and then flew off. I had already been here and learned the word from the nearby wall, so this was kind of odd. I was still able to absorb the soul of this dragon, though.

http://www.uesp.net/wiki/Skyrim:Dragon
There is a bug that causes dead dragons to appear, but it could also be nearby wildlife that killed it. It did happen to me at Autumnwatch Tower with two trolls.

I had a dead dragon following me around for ages. Mostly it lived in the ditch just inside the Whiterun gate but also showed up in the strangest of places.

Like when I did the Sheogorath quest the dead dragon was dropped on top of the daedra prince!

Well, the bug only mentioned skeletons falling from the sky. This one was intact, and on the ground. Nothing in the area besides a fox and the dragon that was flying.

hmm.....might be a new bug. I never saw a dead dragon just like that. If you have Detect Life and/or detect dead try scanning the area

Don't turn your back on that fox!

Interesting side-note: I actually had a fox attack me while I was riding Shadowmere the other day. Maybe there's one super-fox in Skyrim? ...probably just a texture mix-up.