Scientists have discovered 20 new animal species living in the Bolivian Andes. The findings of the 14-day expedition into the "heart" of the region were published by scientists Tuesday.

During the expedition, scientists were able to catalog several new plants and animals, including previously cataloged species not seen by humans for decades. Scientists trekked through the rugged mountains near the Bolivian capital of Lapaz and into the Zongo Valley as part of the expedition.

The region is home to several well-preserved habitats that have remained relatively undisturbed. The habitats are known to have lush biodiversity, which makes them the perfect home for unique species of plants and animals.

In the published findings, scientists discovered new animal species such as the Mountain Fer-de-lance Viper, the Lilliputian Frog and the Bolivian flag snake. A number of new orchid species and butterflies were also discovered.

The expedition into the region was led by the nonprofit environmental group Conservation International. The expedition's leader, Trond Larsen, said in an interview that they really didn't expect to find so many new species let alone ones that were thought to be extinct.

One of the species that were rediscovered was the devil-eyed frog, which was last sighted more than 20 years ago. Another thought-to-be-extinct animal that was rediscovered was the satyr butterfly - last seen by humans more than 98 years ago.

"[In Zongo] the noises you hear are from nature - all sorts of insects, frogs and birds calling, wonderful rushing sounds and cascades of waterfalls. Everything is covered in thick layers of moss, orchids and ferns," Larsen said.

The environmental organization said that a lot of the animals in the Zongo Valley can't be found anywhere else in the world. Many of the animals had been forced to move to higher ground in search of cooler conditions and to escape the effects of global warming.

Larsen said that unless people act to protect the forest corridors the unique flora and fauna of the region could be lost forever.

"Unless you keep those corridors of forest intact then those animals and plants have no way to move and no way to adjust to those changing conditions. That's why protecting places like the Zongo is so essential in the face of climate change," Larsen said.