Wikipedia
Dapingian
The Dapingian is the third stage of the Ordovician and the first stage of the Middle Ordovician. It is preceded by the Floian and succeeded by the Darriwilian. The top of the Floian is defined as the first appearance of the conodont species Baltoniodus triangularis which happened about million years ago. The Dapingian lasted for about 2.7 million years until about million years ago.