The now extinct Falkland Islands wolf didn't raft on ice to the isolated islands.
The only land-based mammal on the Falkland Islands, some 460km from Argentina, probably got there chasing prey across a frozen sea, University of Adelaide researchers say.
The origins of the wolf have been a natural history mystery for more than 320 years when it was first recorded by British explorers, the researchers say in the journal Nature Communications.
Charles Darwin considered the puzzle after seeing a Falklands wolf in 1834: "As far as I am aware, there is no other instance in any part of the world, of so small a mass of broken land, distant from a continent, possessing so large a quadruped peculiar to itself."
The wolf was hunted to extinction in the 19th century.
Theories have suggested it rafted there on ice or vegetation, crossed via a now-submerged land bridge or was transported by early South Americans.
But Australian Centre for Ancient DNA (ACAD) researchers say that's not likely after testing pieces from the skull of a wolf collected by Darwin and a stuffed exhibit found in the attic of Otago Museum in New Zealand.
They found the wolf did not become isolated from a sister species of mainland wolf, the now extinct dusicyon avus, until about 16,000 years ago.
ACAD deputy director Jeremy Austin said they ruled out the land bridge theory because of the absence of other mammals.
But evidence of dramatically lowered sea levels during the Last Glacial Maximum, around 25-18,000 years ago, and submarine terraces of the coast of Argentina provided a "Eureka moment," says ACAD director Alan Cooper.
"At that time, there was a shallow and narrow 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," Professor Cooper says.
Other small mammals like rats weren't able to cross the ice, they say.