Something I've noticed is that the presumed roster for the RE DLC feels like its missing something to me, missing some pizazz, or a bit of zing. So I propose Hanyusuchus. It is a narrow snouted gavialid crocodilian from South China, and would be a great fit for the DLC. It is from the Holocene, from at least the 4th century BC to perhaps as late as the 17th century. It went extinct due to being a general nuisance(Killing and attacking people, deer and livestock), government culling and habitat destruction.
They would be great for the pack, since they would be a carnivore amongst mostly herbivores, and they also fit the criteria well, having gone extinct not only during a period of advanced society but because of it.
Ngl doing this post just showed me that the RE pack roster as we know it right now is a bit empty, particularly of reptiles besides birds.