Early ammonites had simple suture lines traced across their shells, while the sutures on species from the Cretaceous period (145 to ... lived during distinct time periods that can be easily ...

Miners Looking for Ammonite Stumble on Rare Complete Fossils of 'Ocean Predators' From 100 Million Years Ago Evidence of ...

Ammonites are primarily found in marine sedimentary deposits, where they were once abundant during the Late Cretaceous period. This was the time of T-Rex when massive dinosaurs roamed the land.

These animals are known from the Jurassic Period, from about 200 million years ago. Most ammonites died out at the same time as the non-avian dinosaurs, at the end of the Cretaceous Period, 66 million ...