Scientists used major changes in life forms in the fossil record to form the geologic time scale

The correct answer is;

True

Explanation:

Fossils are fundamental to the geologic time scale. ... Rocks formed through the Phanerozoic Eon may have fossils of complicated animals and plants such as dinosaurs, mammals, and trees. We study Earth's history by studying the record of past experiences that are stored in the rocks. The geologic time scale (GTS) is a system of chronological dating that describes geological strata (stratigraphy) to time. It is used by geologists, paleontologists, and other Earth scientists to explain the timing and connections of events that have occurred during Earth's history.