Cretaceous period (138 to 65 million years ago) This period is called the last part of dinosaurs' era, but it does not mean that new dinosaurs did not appear later on. Ceratopsians and pachycephalosaurids appeared in this period. The first fossils appeared in this period were advanced mammals, insects, birds' groups and also flowering plants. Separation of Pangea continent commenced in Jurassic, and then continued. It caused regional difference in plant fossils and animal fossils between north and south of continents. Late Cretaceous was the end of previous success and dissemination of groups and organisms, such as nonavian dinosaurs and ammonites. It was a period that opened the way for appearance of other animals. Therefore, life commenced similar to present time within late Creatceous.