For example, based on the primate fossil record, scientists know that living primates evolved from fossil primates and that this evolutionary history took tens of millions of years.
By comparing fossils of different primate species, scientists can examine how features changed and how primates evolved through time.
These changes typically occur so slowly that they are barely detectable over the span of a human life, yet even at this instant, the Earth's surface is moving and changing.
As these changes have occurred, organisms have evolved, and remnants of some have been preserved as fossils.
When information derived from two outcrops is integrated, the time interval they represent is probably greater than that of each alone.Sequencing the rock layers will show students how paleontologists use fossils to give relative dates to rock strata.Once students begin to grasp "relative" dating, they can extend their knowledge of geologic time by exploring radiometric dating and developing a timeline of Earth's history.Presumably if all the world’s outcrops were integrated, sediments representing all of geologic time would be available for examination.This optimistic hope, however, must be tempered by the realization that much of the record—older than 541 million years—is missing.