Firstly, and probably least excitingly, there's "DragonTurtleBlack" which looks superficially like the current RidingDragonTurtleSkinBlack, but (i) it has red eyes, (ii) the shading is subtly different and (iii) it lacks a lot of the ornate patterns on its carapace. In fact the carapace folds go the other way...
I'm honestly not sure what to make of it. The shell texture doesn't seem to fit the model as well as the current ones and the naming convention for the skin is different to all the others. I guess time will tell.
Secondly, and more excitingly, the Amber version of the Horde Scorpion (aka Madexx) model! The textures are different to the current Madices and it's really very pretty:
The textures also exist in the files for the amber armour, for the datamined new Amber Scorpion Mount, but I can't get them to render currently. I may have to tinker with it a bit.
Finally, there's a new Amber skin for the gyreworm. These aren't beasts anyway, but they're close enough to be of interest. Again the skin isn't just a recolour... it's has quite a few texture differences to the current skins:
I love the big blobs of amber on it!
The fact that there's two new amber things in one patch makes me wonder if they're linked.