Unlikely, but I suppose it is possible.
We really can't know what kind of creatures exist and do not until we vist every single place in Tamriel, But the TES dragons aren't really dragons - they're wyverns.
Wyverns; http://puu.sh/97Bhc/60a37bdaeb.jpg
Dragons; http://puu.sh/97Bic/f50113288e.jpg
Every universe has their own version of creatures. Who gets to decide what the standard appearance of a give creature is? Dark Souls had the Everlasting Dragons, which didn't have legs at all.
Wyverns; http://puu.sh/97Bhc/60a37bdaeb.jpg
Dragons; http://puu.sh/97Bic/f50113288e.jpg
There is no specific defintion on what a dragon looks like. The Dovah may fit the description of a Wyvern, but that doesn't mean it can't be called a dragon.
As for four-legged dragons, Arena had location-pictures that had dragon statues depicted with four legs (most notably Fang Lair ->)However, seeing as Arena's lore is sort of archaic, these depictions of dragons may not be canon.
It would be interesting to see someone go through Arena and make it more consistent with modern TES Lore (maybe better graphics too. At least Oblivion level graphics.)
The Dragonlings of Daggerfall also possess only two legs, but like Arena, the lore may not be relevant. More so because Dragonlings technically are not related to the Dovah at all.
Not true, they had legs. But you are right about the portral. Same thing with magic, teleportation, gods, and dozens of other things.
Perhaps on what is believed to be their land of spawning- (Akavir.) There will most likely be more different species, types and familys of dragons there.
Wyverns; http://puu.sh/97Bhc/60a37bdaeb.jpg
Dragons; http://puu.sh/97Bic/f50113288e.jpg
wel what yo just said is "the the elder scrols"...
This is unlikely, as there is only one known type of dragon, and they have only two legs. It should be noted that Peryite is sometimes depicted as a four-legged dragon, but he is, of course, a Daedric Prince.
This Mod Exist... But is Dead -____-
REAL 4-Legged Dragons