The unstable climate led to widespread migration, with early Paleo-Indians soon spreading throughout the Americas, diversifying into many hundreds of culturally distinct tribes. The Paleo-Indians were hunter-gatherers, likely characterized by small, mobile bands consisting of approximately 20 to 50 members of an extended family. These groups moved from place to place as preferred resources were depleted and new supplies were sought. During much of the Paleo-Indian period, bands are thought to have subsisted primarily through hunting now-extinct giant land animals such as mastodon and ancient bison. Paleo-Indian groups carried a variety of tools, including distinctive projectile points and knives, as well as less distinctive butchering and hide-scraping implements.