Six Swedish finds of subfossil bison were pollen-analytically dated by Isberg (1949) as originating from pollen zones V–VI according to Jessen's zone system. Recent pollen analyses of fresh samples from the six skulls or horn-cores, besides from a seventh find, have shown that one animal originates from the transition between zones III–IV, 4 from zone IV, one presumably from zone IV or the very beginning of zone V, while one could not be dated.