Ammonite shells are used today as index fossils, meaning they can help date other fossils that are found in the same layer of marine rock. These cephalopods make for ideal index fossils because ...

We are collecting and imaging lots of modern and fossil Ginkgo leaves, including leaves submitted by citizen scientists across the nation, in order to help us better understand how variable the ...

Because some ammonites only lived during specific periods, when geologists find such fossils, they know the age of the geological structure — this makes ammonites index fossils. Ammonites are ...