Exclusive new pictures show a 450-pound Mekong giant catfish. It's the only one caught this year—a bad sign, according to a scientist on the scene.

Vacuum, lawn mower—whatever you call it, Nigersaurus was bizarre. See a 500-tooth dinosaur whose secrets are coming to light.

Nigersaurus—an elephant-size dinosaur with a featherweight skull and a mouth that worked like a lawn mower—suggests that long-necked plant-eaters browsed like cows.

The world's largest trout, overfished to near-extinction in most of its habitat, is still thriving in Mongolia's remote rivers.

For the ferocious, cannibalistic taimen, one of the world's biggest freshwater fishes, Mongolia's remote rivers are its last hope. Part four in a series on "megafishes."

Fishing the world's largest trout, Mongolia's taimen, is encouraged—to help save it.

Children sacrificed by Inca rulers were fed high-quality food for up to a year, sent on a grueling march, and drugged before death, a new study shows.

Watch as language hunters in Australia's outback discover the only known speaker of a language long thought to be dead.

Experts are warning of a "global extinction crisis" of the world's languages and have identified five hotspots where tongues are vanishing most rapidly.

Video: Last Speaker of "Dead" Language

The Mekong catfish travels more than 600 miles (1,000 kilometers) upriver to spawn—a discovery that means a planned dam on the river might spell disaster for the species.

See pictures of the world's biggest freshwater fishes, including a bear-size catfish and a half-ton stingray.

A rich trove of fossils recently found in New Mexico suggests that dinosaurs took a slow path to domination over life on land.

New medical scans bolster the theory that an unidentified corpse is Akhenaten—the heretic pharaoh married to Nefertiti who some believe was Tut's father.

Photos: Who Was Tut's Father?

Watch as archaeologists reveal how they identified the long-lost mummy of Hatshepsut, an Egyptian ruler famous for donning the male garb of a pharaoh.

Two species of ancient penguin have been uncovered in a Peruvian desert, including one that stood almost 5 feet (1.5 meters) tall, a new study reports.