What characterized the defining difference between the evolutionary focus of early *Mammuthus* and later *M. primigenius* features?

Initial pressure for large size/grazing versus later pressure for extreme cold survival

A key analytical takeaway from synthesizing morphological and genetic data is the difference in the timing and nature of selective pressures. The initial formation of the *Mammuthus* genus involved traits like larger size and specialized molars suited for grazing tough vegetation—the initial adaptive pressure was handling large amounts of low-quality forage. The later, much more specialized pressure, driven by extreme climate cooling during the Ice Ages, was the need to survive sustained, intense cold, which resulted in the evolution of characteristic features like the thick coat and smaller ears for heat conservation.