I just looked at the pix for Dragonborn and they look awesome but something is bothering me. What type of Dragon is the Dovahkiin mounted on because it looks like Alduin. I don't totally know what all the dragons look like in Skyrim but I was wondering if someone had an answer or if it is a new one like the blue one in the trailer.

Frost, I think.

if your talking about the dark blue one, it has fins, and a leathery hide as opposed to the spines and scales of the normal dragons. all of this shouts aquatic dragon to me. (no pun intended)

Indeed it is, strange how I never took into detail their actual appearences. I just went around randomly killing them........

It does have a rather aquatic looking appearence, maybe it is something to do with the water. Maybe it's attacks or that's where it comes from. I dunno it's wierd.

Looks like the vanilla game Frost dragon.