Mystery of Darwin's strange South American mammals solved

Last unresolved 'major problem in mammalian evolution' - the origin of two ungulates - has been resolved according to researchers

To 19th century British naturalist Charles Darwin, they were the strangest animals yet discovered, one looking like a hybrid of a hippo, rhino and rodent and another resembling a humpless camel with an elephant's trunk.

Ever since Darwin first collected their fossils about 180 years ago, scientists had been baffled about where these odd South American beasts that went extinct just 10,000 years ago fit on the mammal family tree. The mystery has now been solved.