What's 41 feet long, weighs 15,000 pounds, travels in packs and wouldn't mind a bite of your tri-tip sandwich ??

Could be your relatives from Wisconsin, but in this case we're talking about Mapusaurus roseae, perhaps the largest meat-eating dinosaur ever. Paleontologists say they've found fossilized remains of the beasts in Argentina. What they don't know is why the dinosaurs died.