The last major ice age was far more variable than the previous Pleistocen
ice ages but it was never the less a much colder time than we currently live
in.  This means that the temperate regions were much closer to the Equator
than they are now.  These areas were home to the Pleistocene megafauna and
included areas (such as Texas and Mexico) that would be considered tropical
today.  When these areas migrated closer to the Poles with the begining of
the current interglacial period the megafauna suffered because of longer
winters and less favorable conditions for grass growth.

Plains Indians invented Pemmican.  When they made it they wasted very little
of the buffalo they used and ended up with a product that was over 80%
saturated fat.  Here on the dry grasslands of Texas you would starve if you
didn't eat meat.  Especially when after a long hot dry summer the grass
ignites and all plants are gone ( a time of great feasting for carnivores).
Winter, although much wetter, is not much better as it often gets very cold
( there's nothing between here and tha North Pole but one strand of barbed
wire - and it's blowed down) and plants only are able to grow in early
spring.

Ray Audette
Author "NeanderThin"
http://www.neanderthin.com