Dapingian

The Dapingian is the third stage of the Ordovician system and the first stage of the Middle Ordovician series. It is preceded by the Floian and succeeded by the Darriwilian. The base of the Dapingian (and 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 1.9 million years until about million years ago.

==History== The Ordovician was divided into three series and six global stages in 1995. Although at the time of 2005 GSSPs for the overlying Darriwilian and underlying "second stage" had already been ratified, definition of a GSSP for the first stage of the Middle Ordovician Series caused difficulties due to the deficiencies of the selected biohorizon and section. The Dapingian was the last Ordovician stage to be ratified, and was initially referred to as an informal and unnamed "third stage" corresponding to the early part of the Middle Ordovician. This third stage was meant to represent the appearance of several major index fossils. The conodont Baltoniodus triangularis, a species found in Baltica and China, defined the base of the regional Baltoscandian Volkhov stage. Another conodont, Tripodus laevis, defined the base of the Whiterockian stage in western North America. T. laevis was also roughly correlated with the appearance of the graptolite Isograptus v. lunatus.