The fauna of South America consists of a huge variety of unique animals some of which evolved in relative isolation. The isolation of South America allowed for many separate animal lineages to evolve, creating a lot of originality when it comes to South American animal species.[1] The isolation of South America had an abrupt end some few million years ago when the Isthmus of Panama was formed, allowing small scale migration of animals that would result in the Great American Interchange which caused many marsupials such as Thylacosmilus to go extinct.[2] South America is the continent with the largest number of recorded bird species.[3]
Additionally, speciation has occurred at a higher rate in South America than in other parts of the world.[1] This is likely due to the large amount of land mass close to the equator. The amount of speciation at the equator compared to the rest of the world is much greater.[4]