The remaining stage of these “middle” levels may be identified—most arbitrarily—as the Eden, or parallel-flaked, point horizon. Fluting of projectile points still occurs, but the distinctive and exceptional feature is the beautiful pressure-flaking illustrated on page 155. Other types of projectile points include Gypsum, Plainview, Scottsbluff, Lime Creek, Angostura, and perhaps Agate Basin. The time span seems to be from perhaps 7,000 to about 10,000 years ago. The makers of these points also tended to be bison hunters. _Bison occidentalis_ may have been the chief game,[78] although there continues occasional association with _B. antiquus_, and there begins an identification with _B. bison_, the “buffalo” of Plains Indians in recent times. In the two thousand years following the Folsom climax—that is, from about 7,000 to 9,000 years ago—notable transitions occurred in the technologies and economies of early man. Handsome projectile points became noticeably diversified in shape, and perhaps in size. Many continued to be made with a superb craftsmanship that persisted to historic times. Economically, as we shall see in the next chapter, there was a major shift of emphasis. This was due in large part to the great extinction of Pleistocene mammals, which was in progress by 8,000 years ago and essentially completed 5,000 years ago. During this time, the era of specialized big-game hunters came to a close. The human populations that survived seem to have turned their attentions to the generalized hunting of lesser game. Their economies were first augmented by, and then focused upon, food collecting. For many groups, such as the Indians of central California, exploitation of wild seeds and nuts became a specialized and satisfactory means of subsistence in a climate whose wet winters and dry summers severely limited agriculture. Elsewhere, seed collecting was replaced by plant domestication—an important first step—then by plant cultivation and ultimately by agriculture. Of these late trends in American prehistory, the scope of this book allows us to touch on only the Cochise cultures and other seed-collecting traditions of apparent antiquity. Back of 15,000 Years? We have hardly mentioned the earliest period of American prehistory. As in the Old World, the most ancient is the least known. There are many places in the west and southwest of the United States, and some in Mexico and South America, where materials of what seems impressive antiquity have been detected. We say materials, rather than cultures, for they are often suspect.