The animal with Burrowing.
Also, per the rules the animal with Carnivorous can't ever attack when it's fed, unless it had Fat Tissue. Once an animal is full, it can't consume food.
In order to build Fat Tissue, it requires the animal to be fully Fed first. It is an option to build it and wont make an animal extinct if you haven't filled the Fat Tissues in the extinction phase of the game. So a carnivorous animal can not attack an animal fully fed even if its fat Tissues are not Full, if it has the Burrowing trait.
Keep also in mind that an animal with Borrowing can still fill its fat tissues after its fully fed and protected by carnivorous trait attacks.