Prehistoric and modern bison. Above, at the left, is an outline of typical horn cores of 'Bison antiquus' whose bones have been found with Folsom points. Its horns were longer and straighter than those of the buffalo of today, 'Bison bison' shown at the right. Below is a still larger and more ancient type, 'Bison latifrons', with an 88 inch span (McGowan and Hester, 1962, p. 199).
Extinction dates of the Pleistocene mammals in North America. More than half of these 16 mammals seem to have died out between 10,000 and 8,000 years ago. (McGowan and Hester, 1962, p. 196).
Disjunct distribution of the ring-ouzel (a thrush) in Europe. During the last glacial distribution was continuous. With amelioration of climate it broke up into northern and high mountain areas.