The Grand Canyon is located in Arizona, USA. It is estimated to have formed over five million years ago as the Colorado River began to create a deep channel (canyon) in the surrounding rocks. Before the canyon formed, an ancestral species of antelope squirrel lived in the area. An antelope squirrel is a type of rodent and member of the squirrel family, Sciuridae. It is estimated that around 3.6 million years ago, an ancestral species diverged into the two species that are present today. • Harris's antelope squirrel, Ammospermophilus harrisii, has its habitat range extending from the south rim of the canyon. • The white-tailed antelope squirrel, Ammospermophilus leucurus, has its habitat range extending from the north rim of the canyon. Fig. 4.1 shows the location of the Colorado River in the Grand Canyon and the location of these species of antelope squirrel. [Figure 4.1]