in the early to mid-Oligocene, as primitive marmots and chipmunks are known from the Late Oligocene of North America. The fossil record of the "true" ground squirrels is less well known, beginning only in the mid-Miocene, when modern susliks and prairie dogs are known to have inhabited their present-day range already.

Whether the Marmotini dispersed between North America and Eurasia via "island-hopping"