Animals

Until the end of the last ice age, American cheetahs, enormous armadillolike creatures and giant sloths called North America home. But it's long puzzled scientists why these animals went extinct about 10,000 years ago.

Bizarre worm that looks "like the rump of a pig from one side and Mick Jagger's lips from the other" may be in the middle of an evolutionary leap, scientists say.

The largest salmon species ever discovered, Oncorhynchus rastrosus may have used its distinctive, tusk-like teeth to compete with rivals, defend against predators and dig nests.

"Exceptionally preserved" fossils of an ancient shark that lived alongside the dinosaurs has finally revealed what the predator looked like — and why it may have gone extinct.

Bioluminescence traces back to the Cambrian era — 540 million years ago — and could have been used for communication, courtship and camouflage among the earliest ocean creatures.

Why don't dogs claws retract like felines' do?

The southern grasshopper mouse is largely immune to the venom of the Arizona bark scorpion and will resort to cannibalism when times are tough.

Researchers discovered the remains of a huge dinosaur named Bustingorrytitan shiva last year and have now released artistic reconstructions of the Cretaceous giant.

Visitors at Ranthambore National Park in India captured rare footage and images of a tigress and her three 1-year-old cubs feasting on the carcass of a crocodile after killing it.

From Titanoboa and Vasuki — prehistoric snakes as long as a Tyrannosaurus rex — to modern-day pythons and boa constrictors that can swallow humans whole, these are the biggest, heaviest and longest snakes to have ever lived on Earth.