Combined with the well-established geological theory of , common descent provides a way to combine facts about the current distribution of species with evidence from the fossil record to provide a logically consistent explanation of how the distribution of living organisms has changed over time.
Instances of these modes have been researched in both the laboratory and in nature.
Due to the absence of information such as reproductive behavior or genetic material in fossils, paleontologists distinguish species by their phenotypic differences.
For many years, geologists could only roughly estimate the ages of various strata and the fossils found.
Evidence from was gathered by some of Darwin's contemporaries; , , and are all readily explained by.
However, a recent study suggests an earlier, transient bridge existed 13 to 15 mya.