The Features of Dasyclad Algae and the Dasycladaceae Fossils in Jiaonan Region

The features of all fossil assemblage from Jiaonan region are equal to those of the plant in the forth stage or the fifth stage. The time of samples association of Dasycladaceae algae in Jiaonan area should be in early Cretaceous period. The group of Dasycladaceae algae in Jiaonan region is marine plant, and belongs to the Tethys paleobotanic province. They began to distribute westward and eastward from Triassic period in a radiating way. And the geographical position was in tropical or subtropical zoneat that time.