The Archaic period in the Americas saw a changing environment featuring a warmer more arid climate and the disappearance of the last megafauna. The majority of population groups at this time were still highly mobile hunter-gatherers; but now individual groups started to focus on resources available to them locally, thus with the passage of time there is a pattern of increasing regional generalization, for example the Southwest, Arctic, Poverty Point culture, Plains Arctic, Dalton, and Plano traditions. This kind of regional adaptation became the norm, with reliance less on hunting and gathering among many cultures, with a more mixed economy of small game, fish, seasonally wild vegetables and harvested plant foods. Many groups continued as big game hunters, but their hunting traditions became more varied, and meat procurement methods more sophisticated. The placement of artifacts and materials within an Archaic burial site indicated social differentiation based upon status in some groups.