There are some weird animals in Vvardenfell. Netch, Kwama, all those various bipeds... Everywhere else we've been in Tamriel seems to have normal animals, so why did such odd, exotic creatures form on Vvardenfell? Was this just a creative decision, to spice up the traditional medieval setting, or is there some lore explanation for why the north-east part of the continent has such insane life-forms? For instance, is there some evolutionary reason that so many animals on the island have two legs instead of the usual four?

Also, this question is only semi-related, but how did life in general start on Nirn? I know the Hist and Ehlnofey were survivors from the previous worlds, and that men and mer are descended from the Ehlnofey, but where did all the trees and rats and deer and whatnot come from? I suppose they were created by the Aedra along with the rest of Nirn? If that's the case, then does evolution occur in Mundus? Are the various life forms the same as they were when first created, or have they changed over time?

The Aedra made it all. About evolution... Im not sure...
The Breton is a sort of "new" race... They are half-breeds, half Mer, half Man. Propably bosmer and nords/imperial breed together.

But other than that, I dunno know.


And about Vvardenfell... well that sure is a good question... The twolegs thing could be to get higher up and reach the good parts of the few plants there exists in Vvardenfell/Morrowind.
Vvardenfell and Morrowind is also the province closest to Akavir, perhaps there was some Pangaea thing there long back in times? Making the odd creatures of Akavir emigrate to Morrowind? Or perhaps the Akavir invasions brought new odd animals with them that could survive the tough climate of Morrowind?

Some animals could also have gone from Black Marsh (jungle/marsh place, weird animals are bound to exist there) and then moved north into an area which is not TOO different for the animals there, then they would adapt to the easier climate, eventually moving north and reaching Morrowind in some odd way.

hmm... I can't really see a "pangea" type of thing happening. Why would the Aedra make continents that move?
But immigration from Black Marsh and Akavir are both good ideas. I had actually forgotten about this, but there are some series of books that describe some guy's travels to Black Marsh and Valenwood, and there were some really strange creatures described in those as well.
I guess Morrowind's animals aren't too unusual by Tamrielic standards, just *different*; and that it was just Cyrodiil's (relative) normality that skewed my perception.
Bipedalism still has me stumped though. Your idea works for Guar (although the fact that they mainly live in the grasslands detracts from it a bit, since grass is generally quite close to the ground), but Kagouti and Alit both seem to be very predatory.

"A Children's Anaud" claims that the reason that there are multiple continents is because much of the land sank during a war waged by the Ehlnofey.

Probably Altmer and not Bosmer. Because the Breton are magic-skilled and the Bosmer aren't magic-skilled.

And indeed, in rest of Tamriel there are some exotic creatures. Cyrodill for example; Have you seen in real life a Land Dreugh?

Also, considering region, the altmer are more likely residents of the high rock area.

Morrowind's wildlife is the way it is because those are what animals live in Vvardenfell, in real life, different parts of the world have different animals living in them too, and sometimes, the animals of one region can be very different from those in another. This is because in separate places, different animals that are suited to different environments evolve, so you won't see polar bears on a tropical island (Unless you're watcing Lost.) because that's not where they're notive to. Morrowind is the same way, In Morrowind, you see nix-hounds or kwama because that's the kind of animals that live there. As to why Morrowind's wildlife is so much more... exotic than the animals we saw in say, Highrock or Cyrodiil when these were portrayed in games, I'd say it's because in Morrowind, Bethesda was actually trying to create a unique and interesting game world instead of just going for more boring generic fantasy garbage. But that's the reason for the design choice, a better in-universe explanation might be because Vvardenfell's environment is also more exotic, and it demands different creatures. Admitably, I'm not exactly certain WHY something like a guar would be so suited to living in Morrowind, but nonetheless it's still a welcome change from what we usually get in fantasy games.

However I suspect Vvardenfell isn't the only place whose creatures differ from the standard fantasy fare, I'd expect to see some pretty exotic things in Black Marsh too, for example.

It's just a simple design thing. Before Morrowind, lore wasn't completely fleshes out. Tamriel was pretty similar to Earth. Morrowind actually had hardly any wildlife. It was just one big ashy lava filled wasteland. It changed. Oblivion was just trying to get mainstream players. Guars aren't mainstream.

That's the boring explanation. But I'm gonna have to go with the gods did it. More fun. ^_^

The Guar two-leg was perhaps to make it see OVER the grass? In case any Nix-Hounds were sneaking to it? The Kagouti and Alit are not the flock-creatures that the Nixix are and therefore they would trust brute force to take down the guars... Hm... Perhaps... Nah... I dont really know... But Alit and Kagouti are perhaps some distant relative of the Guar... Which have become carnivore... Perhaps?

It reminds me of Australia in a way: a lot of its creatures are unique, not found on other continents because of Australia's relative isolation.

Would be my take on it.
But A Wizard Did It is not really an explanation either...

agreed

Vvardenfell isn't isolated. That's like saying Britain is isolated from europe, because it's an island with a bit of water. Vvardenfell isn't far from the rest of Morrowind, at all. There would only be a few miles difference. Morrowind is attatched to the rest of Tamriel. I think each province could easily have it's own unique wildlife. If anything, the only place in official Tamriel that's like Australia is summerset. And even that isn't too far away.