Summary:
- Fossils are the preserved remains or traces of organisms that lived in the past.
- Fossils can be dated in two different ways: relative dating and absolute dating.
- The fossil record is the record of life that unfolded over four billion years and pieced back together through the analysis of fossils.
- A molecular clock uses DNA sequences (or the proteins they encode) to estimate relatedness among species.
- The geologic time scale divides Earth’s history into divisions based on major divisions (such as eons, eras, and periods)