Final answer:
The loss of hominoid diversity in the Late Miocene can be attributed to climate change and the opening of previously inaccessible areas.
Step-by-step explanation:
In the Late Miocene, two factors are hypothesized to explain the loss of hominoid diversity. The first factor is climate change. The Late Miocene was a period of cooling, with changing sea levels and an increase in ice at the poles. These environmental changes may have led to the loss of suitable habitats for many hominoid species.
The second factor is the opening of previously inaccessible areas. During the Late Miocene, North and South America became connected through the Isthmus of Panama, and a land bridge appeared between Alaska and Siberia. This allowed for the movement of hominoid species between regions, leading to competition and potential extinction.