By establishing linking features of fossils in different age brackets through radioactive dating
Explanation:
Radioactive dating estimates the age of fossils and rock. Fossils are remains of living organisms that are primarily found in the sedimentary rocks. Carbon dating is used to determine the age of the fossils that are not older than 50 thousand years.
For fossils older than that uranium dating is used. Based on the age estimation of fossils, fossils belonging to the same age bracket are grouped from the oldest time to the most recent time thereby marking the common characteristics of different fossils at each age brackets. In this way radioactive dating helps the scientist in establishing evolutionary links.