The holotype specimen hails from Wyoming in the United States, in strata of the Gidley Quarry dated to the Torrejonian stage of the Paleocene.

Remains of Baiotomeus lamberti have been discovered in Montana in the United States, in the Medicine Rocks of the Tongue River Formation, which have been dated to the Paleocene.

Baiotomeus russelli has been discovered in Alberta, Canada, in Cochrane 2 of the Paskapoo Formation, which has been dated to the lower Tiffanian stage of the Paleocene.

(Scott et al., 2002) According to the same authors: The species name honours L. S. Russell "for his pioneering research on the mammals from Cochrane 2".

Cochrane 2 has also been interpreted as correlating to the Porcupine Hills Formation, but recent studies suggest that it is part of the Paskapoo, as originally concluded by Russell in 1929.