Although we haven't seen any potential models for either of these creatures, the quilen are the lion-like companions of the mogu, one of the villainous races of the new expansion. You can see what the quilen look like in the screencap above. As with just about every new creature I run into in Pandaria, I pretty much wanted to throw a saddle on this thing from the first moment I laid eyes on it, so needless to say, I'm happy with the choice.
I didn't really need any more convincing to get the Collector's Edition of Mists of Pandaria. Frankly, the soundtrack pieces I've heard plus the potential of a new art book were more than enough to snag my interest. But the possibility of both a pet and a mount have sealed the deal, so to speak.
Edit: Wowhead has now updated their post with a 3D rendition of the model for the mount. Please note, there are no textures for the mount as of yet, but you can get an idea of how the armor sits on it, anyway!
It's open warfare between Alliance and Horde in Mists of Pandaria, World of Warcraft's next expansion. Jump into five new levels with new talents and class mechanics, try the new monk class, and create a pandaren character to ally with either Horde or Alliance. Look for expansion basics in our Mists FAQ, or dig into our spring press event coverage for more details!