With its feathered body and duck bill, the eight-ton Deinocheirus wades through an Asian wetland in search of relief from pesky biting flies.

Within the snow-covered forest, a tense standoff develops between ancient rivals, Pachyrhinosaurus and Nanuqsaurus.

Not many can intimidate North America's top predator, T. rex, whose size and bite are a deadly combo—except for a giant winged foe.