A 2013 study also identified several fossil species formerly in Martes that are more closely related – and probably ancestral – to the fisher, moving them into Pekania as well.

[2] Current studies suggest that the fisher is more closely related to the wolverine and tayra than it is to martens, confirming its placement in the separate genus.

[1] The earliest known fossil member of Pekania is P. occulta from the Rattlesnake Formation of Oregon, which is about 7 million years old but already very similar to the fisher.

[1] Although endemic to North America today, Pekania may also have occurred in Asia in the past, with the first species known from between 2.5 and 5.0 million years ago.

The modern fisher has been found as early as the Late Pleistocene era, about 125,000 years ago.