The exciting news is that, currently, this pet is not exotic, meaning it can be tamed by a hunter of any spec, not just beast masters. Of course, do remember that this is PTR, and therefore subject to considerable change before launch. There is a requirement to tame it, though, which is an item dropped from the dinomancers based on the Isle of Giants, the Ancient Tome of Dinomancy.
This currently has quite the high drop rate, although it is not 100%, but again this could be nerfed down to size on live servers. There currently are no other hurdles to navigate to obtain one, unlike the pets from previous patches and their greater challenges, despite the PTR patch notes stating the following:
Dire Horns have been added as a tamable species for Hunters that have learned the required skill. Aspiring Dire Horn owners should seek out clues regarding these auspicious beasts.
It's not yet known whether these dinosaur-style creatures will be added into old zones where they'd fit in, but it seems likely that they will remain around Pandaria and on the Isle of the Thunder King. I think they're adorable! The triceratops-heavy nature of patch 5.2 is just fine by me.
Mists of Pandaria is here! The level cap has been raised to 90, many players have returned to Azeroth, and pet battles are taking the world by storm. Keep an eye out for all of the latest news, and check out our comprehensive guide to Mists of Pandaria for everything you'll ever need to know.