An era is a period of time specified for the purposes of chronology or historiography, such as regnal eras in the history of a monarchy, calendar eras for a certain calendar, or geological eras defined for Earth’s history.
how do scientists determine when an era begins and when it ends
How do scientists determine when an era begins and when it ends
Due to widespread extinction, scientists determine when an era starts and ends. The fossil record, which displays extinct animals from Earth’s history, helps scientists estimate when significant changes occur.