By the way, it is worth pointing out that ocean curents count for a lot,
Maybe before the Pliocene, but whenever a n expedition finds a fossil specimen, trust me, they are smart enough to know to bring in pollen specialits and microstratigraphy guys to determine the detailed context and environment of the fossil. When they find a mammoth in a peat bog in Italy, the pollen and microstratigraphy lets us know what the context is. Many more mammoths probably passed through and many died during the migration. Its just that conditions for fossilization were not as optimal as areas of melting permafrost where mammoths were routinely trapped in mud holes and died and were better preserved. (Its been said that there are 150 MILLION fossil mammoths in Beringea). Is that because they were exclusive to that environment or were they passing through on a migratory urge?.I submit its the latter.
We see many more mammoths in steppe climates because the fossilization was more easily accomplished there (mostly because of loess deposits or fluvial deposits). Forests had only cave drops, talus slopes or peat bogs wherein fossils could accumulate( or where landslides could bury an animal,. Most of the Appalachian, Floridian, and Ozarkian Mammoth fossils were found in these forest type environs . If Id look at these fossils from most of the Southern and Mid Atlantic, Id say that most mammoths lived in forests . Fact is, they passed in and through many environments and while many were obligate grazers, some were equalyy obligate browsers. SInce none of them were ruminants, their seasonal food needs would mean that theyd need some sort of winter range because prairies are crappy for nutrients when dormant. And since most nutrients in the tall grasses are in the crown, Id imagine that these grazers would have to migrate south to the short grass prairies where nutrients are stores in the stems near the surface. Passing through stands of thickets and forests would provide them
Most state geological surveys have produced overburden maps to show where piles of glacial drift, moraines, and outwash are deposited. Consequently, these maps also show the large areas that WERE NOT glaciated and, of these, whatareas were pretty much circum glacially derived or were climax forest. In theAppalachians through the Ozarks, the amounst of forested area was quite high. The only differences between pleistocene forests and recent climax forests was that most pleistocene forests contained as much pine and fir as our present canadian boreal forests. Oaks and Hickories were in the deep south then and only migrated into the northeast by the Dryas time.