Scientists believe they have discovered a new group of giant apes in the jungles of central Africa.
The new ape has some gorilla (pictured) characteristics
The animals, with characteristics of both gorillas and chimpanzees, have been sighted in the north of the Democratic Republic of Congo.
According to local villagers, the apes are ferocious, and even capable of killing lions.
A report about the mysterious creatures is published in this week's edition of the UK magazine New Scientist.
If they are a new species of primate, it could be one of the most important wildlife discoveries in decades.
The discovery of these apes "reveals just how much we still have to learn about our closest living relatives," New Scientist says.
They stand up to two metres tall, the size of gorillas, and like gorillas, they nest on the ground, not in trees.
'NEW' GIANT APE
Large, black faces (like gorillas)
Up to two metres tall (6.5ft)
Weigh 85kg-102kg (187lb-224lb)
Males make nests on the ground (like
Diet rich in fruit (like chimps)
But they live hundreds of km away from any other known gorilla populations, and their diet is closer to that of chimpanzees.
Primatologist Shelly Williams is thought to be the only scientist to have seen the apes.
During her visit to DR Congo two years ago, she says she captured them on video and located their nests.
She describes her encounter with them: "Four suddenly came rushing out of the bush towards me," she told New Scientist.
"If this had been a bluff charge, they would have been screaming to intimidate us. These guys were quiet. And they were huge. They were coming in for the kill. I was directly in front of them, and as soon as they saw my face, they stopped and disappeared."
The discovery has baffled scientists. There are three controversial possibilities to explain the origin of the mystery apes:
So far, researchers have little to go on, but they now plan to return to northern DR Congo to study the apes further.
- They are a new species of ape
- They are giant chimpanzees, much larger than any so far recorded, but behave like gorillas
- They could be hybrids, the product of gorillas mating with chimpanzees.
In the meantime, there are fears that unless measures are taken to protect them, poaching could threaten this new group of primates before the mystery of their identity is resolved.
"This is a lawless area," says Kenyan-based Swiss photographer Karl Ammann, who tipped Ms Williams off about the apes.
"The government has practically no control over hunting. If we found something interesting it would attract more investment. People would be more interested in conserving it."