ABSTRACT
In actual fact the great majority of Arctic or Boreal species make their appearance well before the Wurm. As early as Gunz II one meet the first Arctic mammals: the reindeer, musk ox, a form related to tundra vole, the Norway lemming and possibly also a member of the Arctic lemming genus Dicrostonyx. The steppe mammoth also appears at this time, as well as the snow vole, a cold-adapted Alpine form. The first appearance of species that are still in existence seems to have occurred in the Astian, when one find pygmy shrew, pond bat, longwinged bat, common field mouse, and possibly bank vole and steppe pika – a total of six species out of the one hundred and nineteen living forms with a fossil record. About fifty one modern species make their appearance in the early Middle Pleistocene. The Pleistocene fossil record may in future solve the problem of how species originate.
