What evidence from fossils did Charles Darwin use to support evolution?

Charles Darwin utilized the fossil record as a key line of evidence to support his theory of natural selection by observing patterns of species distribution over time.1

Specifically, Darwin noted that the fossil record revealed instances where similar-looking species occurred in the same rock layers or in successive layers of rock. This clustering of closely related species in time suggested that these organisms shared a common origin and had evolved or branched off from a common parent species.1

Additionally, during his travels, Darwin discovered significant fossil remains in South America, such as those of extinct armadillos, anteaters, and sloths. These findings indicated that extinct mammals had been replaced by their own kind, leading him to consider the existence of an unknown "law of succession" that linked extinct forms to living ones. By comparing the observable traits of these fossils with those of living organisms, Darwin was able to develop a better understanding of how different lines of life emerged and changed over time.21