GIANT STINGRAY
What grew 17 feet across, had a 10 inch poison spike in its tail and was strong enough to drag a boat filled with people? In this case, a prehistoric super-fish that is still lurking around in fresh and brackish waters from the Mekong river to northern Australia. Stingrays have been around since a few million years after the dinosaurs died out, and have proven to be a successful design, much like the sharks they descended from.
The giant stingrays use that tried and true ancient design, but have somehow managed to survive ice ages and even the catastrophic Toba event. They were featured on Animal Planet’s River Monsters, and despite the host’s tendency to exaggerate damn near everything, they are incredibly dangerous to fool around with, even if you don’t know you are fooling around with one. They are notorious for putting their neurotoxin covered spike completely through limbs. I guess, on the plus side, if there is one, at least they won’t try to eat you.