The discovery of lost species rarely happens, which is why such an event is exceptional, scientists say.

Researchers have found two mammal species previously thought to be extinct: a small opossum with an unusually long finger and a squirrel species with an exceptionally long tail.

Researchers in Indonesia have discovered an opossum and a flying squirrel believed to have been extinct for 6,000 years, but they are keeping the exact location secret to protect them from animal traffickers.