You have the CHANCE to hatch one. You are more likely to get a Kraken or a Forest Lord. Any time you hatch 2 school pets from the same level pet quests, you have a chance at a hybrid.
I have a question I been trying to get a forlorn sabertooth and evertime I hatch with someone I use avenging fossil but I don't get the hybrid are there other ways to get forlorn sabertooth?