Answer:
Darwin used to support his theory of evolution through evidence for three evolutionary patterns.
1. In South America he found fossils of extinct forms of armadillo and giant ground sloths. However, at the same time he observed that extant species of sloths and armadillos resembled closely these extinct fossilized organisms. This represented the main pattern of evolution: the replacement of extinct species by modern ones.
2. The second pattern is the geographic replacement of one species by another. These species are similar with each other and at the same time distinct.
3. The third pattern is similar to the second, except the geographic replacement occurs on separate islands.
All these led to the idea of natural selection and the theory of evolution