Simplify the following text for a Grade 11 native English-speaking person.
Original: Biologic stratigraphy was based on William Smith 's principle of faunal succession , which predated , and was one of the first and most powerful lines of evidence for , biological evolution .
Simplified: Biostratigraphy was based on William Smith 's principle of faunal succession , which was one of the first and most powerful lines of evidence for evolution .