Deep beneath the water's surface, the world's largest predator—the Mosasaurus—lies in wait to ambush unsuspecting prey.

A journey through an underground cave in North America turns perilous when a young Triceratops is separated from its mother.

A pregnant Tuarangisaurus is in distress—and her young calf can sense it—as she travels waters that are home to the ocean's deadliest predators.

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

In a drought-stricken basin where much has perished, an old Pachycephalosaurus bull defends his leadership against a young challenger.

As sea levels drop and continents shift, animals begin migrating to unknown territories full of new possibilities—and new threats.

With much of the planet's water supply frozen, rock-climbing sloths and marsupial lions must find a way to withstand barren landscapes.

Giant herd animals thrive with the expansion of the grasslands, dominating the plains—but fearsome hunters shadow their every move.

In a world covered in ice, woolly mammoths and saber-toothed cats fight to survive the coldest temperatures in millions of years.

Rising temperatures mean every habitat on the planet is transforming, and for the Goliaths of the Ice Age, the world as they know it is ending.