You have discovered a fossil-bearing layer in East Africa and you wish to estimate its age. There are abundant fossils of many savanna species, and you have identified most of them to species or genus. You know that the genus Equus makes its first appearance in Africa at 2.3 mya, and the species Connochaetes gnou first appears at about 1.07 mya.
1) If your site includes Equus but not Connochaetes gnou,: it may date back to between 1.07 and 2.3 mya
2) If your site includes both Equus and Connochaetes gnou,: it is probably younger than 1.07 mya
3) If your site contains neither Equus nor Connochaetes gnou,: you cannot determine the relative date of this site using these species