New species of Ecphora snails continued to evolve as the climate changed over millions of years. Today, fossils of several species of Ecphora snails are found from New Jersey to Florida. They are considered index fossils . An index helps readers find certain pages in a book. Similarly, index fossils help scientists determine what page of Earth s history a particular layer of sediment or rock represents.
Index fossils are generally common and widespread.
If you find an Ecphora shell in Maryland, South Carolina, or Florida, you know you are digging in earth that dates to the Oligocene, Pliocene, or Miocene. If you can identify the species, you can more accurately guess its age. For example, Ecphora gardnerae lived during the Miocene Epoch. So any fossils found near it would probably be Miocene species as well. The Miocene Epoch was followed by the Pliocene, which ended less than two million years ago.