A newly discovered leaf-tail gecko, one of three new vertebrate species discovered in the Cape Melville range on the Cape York Peninsula in north-east Australia on March 21, 2013. EPA/Conrad Hoskins / James Cook Univ /LANDOV

An expedition to a remote part of northern Australia has uncovered three new vertebrate species isolated for millions of years, with scientists Monday calling the area a "lost world."

Conrad Hoskin from James Cook University and a National Geographic film crew were dropped by helicopter onto the rugged Cape Melville mountain range on Cape York Peninsula earlier this year and were amazed by what they found.

It included a bizarre looking leaf-tail gecko, a gold-colored skink – a type of lizard – and a brown-spotted, yellow boulder-dwelling frog, none of which have ever been seen before.

"The top of Cape Melville is a lost world. Finding these new species up there is the discovery of a lifetime – I'm still amazed and buzzing from it," said Hoskin, a tropical biologist from the Queensland-based university.

"Finding three new, obviously distinct vertebrates would be surprising enough in somewhere poorly explored like New Guinea, let alone in Australia, a country we think we've explored pretty well," he added.

The virtually impassable mountain range is home to millions of black granite boulders the size of cars and houses piled hundreds of feet high, eroded in places after being thrust up through the earth millions of years ago.

While surveys had previously been conducted in the boulder-fields around the base of Cape Melville, a plateau of boulder-strewn rainforest on top, identified by satellite imagery, had remained largely unexplored, fortressed by massive boulder walls.

Within days of arriving, the team had discovered the three new species as well as a host of other interesting finds that Hoskins said may also be new to science.