Why did camelids become extinct in North America after the Pleistocene?

The extinction of camelids in North America near the end of the Pleistocene Epoch is part of a broader, debated megafaunal extinction event. While the exact cause remains unknown, scientists primarily focus on two major hypotheses:1

• Overkill Hypothesis: This theory suggests that human hunters, such as those associated with the Clovis complex, contributed to the demise of large herbivores by overpredation. Proponents argue that native fauna were unaccustomed to these skilled human predators.23
• Climatic and Environmental Change: This hypothesis emphasizes the impact of abrupt climatic change and the resulting reorganization of vegetation. For example, the expansion of dry shortgrass prairies in the Rocky Mountains may have placed camelids at a competitive disadvantage compared to other grazers like bison.3

It is widely believed that the extinction was likely not caused by a single factor but rather a combination of human activity and environmental stress, with the relative importance of these factors varying by region and condition.23