I've read a bit from the Pocket Guide and I can't seem to find anything that tells what kinds of creatures are native to Summerset. I know Sload once lived there long ago, but do we know what creatures are there now? Or will we just have to wait until they come out with a new game that takes place in that province?

According to my only valid source, every "creature" on Summurset Isle is actually a http://www.imperial-library.info/dfbooks/b062_crystal_tower.shtml

Haha I love that story. "Shut up or you'll get us all fired."
I'm kinda piddling over at http://tamriel-rebuilt.org/?p=conceptart§ion=15263 although they're not doing Summerset, it's still interesting the kinds of creatures some of you fellow fans are coming up with. Those Quagmire thingies are really bizarre looking.

There are goblins. The altmer also train them to be slaves and cannon fodder.

Maybe Durzogs, too.

I doubt there's many interesting nasties still wandering around the pastoral isle. The Aldmer killed them all ages ago;

PGE, 3rd Edition;
"The treasury of the Crystal Tower and the private collections in Summerset offer suggestions of other creatures the early Aldmer may have met in their new home, portrayed in sculpture and tapestry. Some of the beasts are surely (and hopefully) the work of the artist's imagination, but others appear with such regularity, it can only be that they once existed, as bizarre as they seem. Though no one alive has ever seen them, they have names out of legend: Gheatus, a man or a group of men who are formed by the earth itself; the Welwa, strange, holy beasts of horns and savage teeth, depicted as ravagers and saviors of the land; the Ilyadi, giants taller than trees, with eyes that cover their head. These extinct monsters, and others like them, had to be defeated by the Aldmer in the days of yore. "

30 septims say those "creatures" are actually from "old Aldmeris".

Could be, but that would be inconsistent with how Old Ehlnofey is represented elsewhere in Crystal Tower tapestries and the like (i.e., no life at all but the Aldmer themselves).

Not if it's before Jephre stabilized stuff so people aren't shapeshifting like crazy.....

Y'ffre? All that is before recorded Elven history. I doubt even the oldest of the old tapestries would contain any physical descriptions of the chaotic dawn to that degree of detail. Unless it's made up wholesale, of course, or elaborations on the vaguest of folk-memory (like 'Aldmeris').

I'd imagine it would be like what Lorkhan (Talos) turned Cyrodil into, and therefor have many of the same creatures. Deer, wolves, etc. might make a reappearance.

Kinda like the difference between YAHWEH and JEHOVAH.