Around 12,000 years ago, a diversity of horses and their kin (known as equids) roamed North and South America. These animals were hunted by large, mythical-sounding, now-extinct predators, such as saber-toothed cats and dire wolves. In a geologic heartbeat, these animals went extinct, likely due to impacts from early humans. Today, however, two species of introduced equid–domestic horses and donkeys–have established thriving populations in North America. These populations are thought to lack predators capable of hunting them, which is one reason that many conservationists consider them to be unwanted pests and why the federal government spends millions of dollars annually removing them from the wild.
source https://www.lifetechnology.com/blogs/life-technology-science-news/introduced-donkeys-and-indigenous-pumas-are-helping-to-resurrect-extinct-food-webs-in-death-valley
