Mammalia - Rodentia - Geomyidae

Alternative combination: Plesiothomomys potomacensis

Full reference: J. W. Gidley and C. L. Gazin. 1933. New Mammalia in the Pleistocene fauna from Cumberland Cave. Journal of Mammology 14(4):343-357

Belongs to Thomomys according to B. Kurten and E. Anderson 1980

Sister taxa: Thomomys bottae, Thomomys carsonensis, Thomomys gidleyi, Thomomys microdon, Thomomys monticola, Thomomys orientalis, Thomomys talpoides, Thomomys townsendii, Thomomys umbrinus

Type specimen: USNM 8166, a mandible. Its type locality is Cumberland Cave, which is in an Irvingtonian cave horizon in Maryland.

Ecology: fossorial browser

Average measurements (in mm): m1 1.45 x 2.10