The mystery of the Falkland Islands wolf has been solved by new DNA evidence.

Scientists have long wondered how the Falkland Islands wolf made it to the islands. The Falklands sit about 286 miles off the coast of mainland Argentina, and the wolf, also known as the warrah, was the only land mammal native to the island.

Some theorized that the wolves managed to get to the island on a makeshift raft of vegetation or ice, or even by early humans and who domesticated them and transported them to the island by boat. But new research from the University of Adelaide in Australia have found an answer by analyzing DNA, including some from a warrah specimen personally collected by Charles Darwin.

“Previous studies used ancient DNA from museum specimens to suggest that the Falkland Islands wolf diverged genetically from its closest living relative, the South American maned wolf (Chrysocyon brachyurus) around seven million years ago. As a result, they estimated that the wolf colonised the islands about 330,000 years ago by unknown means,” Associate Professor Jeremy Austin told Science Daily. Austin is Deputy Director of the university’s Australian Center for Ancient DNA and a lead author of the study.

But these past DNA studies weren’t looking in the right place.

“Critically, however, these early studies hadn’t included an extinct relative from the mainland, the fox-like Dusicyon avus,” said Austin. “We extracted ancient DNA from six specimens of D. avus collected across Argentina and Chile, and made comparisons with a wide group of extinct and living species in the same family.” As it turns out, the small fox-like animal was the closest relative to the Falklands wolf, and the two canid species diverged only 16,000 years ago.

This solved the mystery of what the Falkland Islands wolf was, but how did it get to the islands? The absence of other land mammals would suggest that there was no land bridge.

“The Eureka moment was finding evidence of submarine terraces off the coast of Argentina,” study leader Professor Alan Cooper said. “They recorded the dramatically lowered sea levels during the Last Glacial Maximum (25-18,000 years ago).”

This low sea level mixed with freezing temperatures could have created an ice bridge that linked the islands with mainland South America.

“At that time, there was a shallow and narrow (around 20 km) strait between the islands and the mainland, allowing the Falkland Islands wolf to cross when the sea was frozen over, probably while pursuing marine prey like seals or penguins. Other small mammals like rats weren’t able to cross the ice.”