content: Luckily, for us and everything else that lives, bear sized amphibians could probably not survive in earth's current atmosphere. The closest monster, in looks and behavior, we currently have are giant wels-catfish, which lurk on the bottoms of rivers and lakes, eat everything they can suck into their maw, and never stop growing. Some of them grow big enough to pull in children, and there are legends of some big enough to eat men.