It's not clear where either pet will come from yet. There was a Thundering Cloud Serpent Hatchling that was on the guild vendor for a bit (NYI). This newly datamined hatchling could be one in the same, but it's still too soon to say.
The Jade Crane Chick could come from any number of sources, but if it's a baby version of the crane mob, I'm very eager to see its model! Even if it's just a miniature version and not a unique baby-ish model, I can't wait to get a preview of it.
There was a third pet added to this latest beta build, but it's not necessarily new. The Singing Cricket was previewed in an earlier build as the reward for the achievement Pro Pet Mob, although it didn't have its own item or spell ID at the time. This pet is currently BoU.
Additionally, MMO-Champion datamined something interesting:
REPORT_BATTLEPET_NAME_CONFIRMATION - Are you sure you want to report %s for inappropriate battle pet name?Looks like players will be able to report any inappropriate names given to companions, which makes sense. If a name is deemed unfit for your toon, why on earth would Blizzard allow you to give that nickname to a vanity pet? Why would anyone want to name a pet something horrible anyway? :(
REPORT_PET_NAME_CONFIRMATION - Are you sure you want to report %s for inappropriate pet name?