River of Death

The scene of the worst mass slaughter in the prehistoric world was discovered by paleontologists in Canada in 1986. Evidence shows that an entire herd of plant eating Pachyrhinosaurus was massacred by a giant meat-eater, Albertosaurus, who left hundreds of bones piled one atop the other. Forensic investigation showed that the bodies were crushed and broken by this powerful, agile and terrifying hunter. Watch as experts recreate events that may have lead up to the carnage of these ancient beasts, revealing a predatory world far more calculated--and complex--than we originally thought.