Give these creatures a wide berth when you spot them in the wild because they're likely to overcome humans with their power, speed, or venom. Some of the killers on the list may surprise you.
Alien-like long, ridged organisms are now classified as the oldest known animals on the planet. The Dickinsonia, approximately 558 million years old, puzzled scientists for decades, but fat molecules finally solve the mystery.
It may be difficult to picture a tortoise actually beating a hare in a race, but it turns out Aesop was right after all. Research shows speedy animals are much slower in the long run.
More than 500 million years ago, funny-looking Ediacaran organisms dominated the planet's oceans. The nature of these creatures have been a long-standing mystery, but now scientists say they are actually Earth's first animals.
Humans are causing Earth's temperature rising dangerously high in present time. Half a billion years ago, it was the evolution of early animals that sparked the planet's first global warming event.
Steer clear of otters because no matter how cute they may appear, things could turn violent in an instant. In Maine, police officers had to fatally shoot a river otter who bit an unsuspecting woman by the beach.
"Mountain lions are more afraid of us than we are of them."
According to a group of researchers from the Scripps Institution of Oceanography and the University of Texas Marine Science Institute, spying on fish love calls could protect them from hungry fishermen.
Researchers found that the "love hormone" oxytocin enables mothers to protect their young.
Hunting wiped out wolves from Denmark two centuries ago, but now they're back.
Welcome the once-extinct oryx to the wild.
Meet Tajiri. The zoo claims the name means "hope," but many said it actually means "rich."
A massive female porbeagle shark, believed to be the biggest ever caught was reeled in at Hartland Point in Devon.