How did South America’s isolation affect the evolution of its Miocene mammals?

During the Miocene Epoch, South America’s prolonged geographic isolation from other landmasses allowed its mammalian fauna to evolve in relative independence, resulting in a high degree of biological originality and endemism.12

This isolation fostered the development of unique and "aberrant" groups that occupied ecological niches filled by different lineages elsewhere. Notable examples of this distinct evolutionary radiation include:3

• Marsupial carnivores: Predators that evolved in the absence of the placental carnivores found on other continents.34
• Endentates: A diverse group including ancestors of modern anteaters, armadillos, and sloths.3
• Native ungulates: Specialized hoofed mammals such as litopterns, which exhibited convergent evolution with horses and camels, and toxodonts, characterized by their long, curved incisors.3

Additionally, the Miocene was a period of ongoing evolution for South American monkeys. This independent trajectory continued until the formation of the Isthmus of Panama millions of years later, which ended the continent's isolation and initiated a period of intense faunal competition.342