Meet ankylosaurus, a dinosaur whose name means "fused lizard." Don't be fooled by this one's yawning, hazy, lazy afternoon stroll down to a river: It might look like a bit of a pushover, but, as you'll see, it's plenty ready for a skirmish.
The lumbering creature with the bony plates on its backside and the clubbed tail was an out-sized herbivore, supporting its 30-foot, 13,000-pound frame on a steady diet of vegetation.
It was no easy go of it for predators that tried to attack an ankylosaur, an armor-plated tank of a dinosaur. One wrong move and they risked getting smacked by the dino's tail.
That's exactly what happens here. Our hero in this video almost looks like he's playing dead, when a young tyrannosaurus rex gets a bit too curious. And then: "Whack!"