Gastropods first appeared in the sea bout 600 million years ago; they later adapted to life in lakes, ponds and streams on land. Gastroods help in reconstructing past environment. Knowing about modern species and assuming similar patters for fossil species, geologists can determine the appearance and depth of ancient sea bottoms and whether the sea or climate was warm or cold. Gastropods are found in all sedimentary rocks in Indiana, but they are abundant only in a few places, such as the gastropod limestone in northwestern Sullivan county.
Our Hoosier State Beneath Us: Paleontology