The Dapingian is the third stage of the

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...

period and the first stage of the

Middle Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The ...

series. It is preceded by the

Floian The Floian is the second stage of the Ordovician Period. It succeeds the Tremadocian with which it forms the Lower Ordovician epoch. It precedes the Dapingian Stage of the Middle Ordovician. The Floian extended from to million years ago. The lowe ...

and succeeded by the

Darriwilian The Darriwilian is the upper stage of the Middle Ordovician. It is preceded by the Dapingian and succeeded by the Upper Ordovician Sandbian Stage. The lower boundary of the Darriwilian is defined as the first appearance of the graptolite species '' ...

. The top of the

is defined as the

first appearance In American comic books and other stories with a long history, first appearance refers to the first issue to feature a fictional character. These issues are often highly valued by collectors due to their rarity and iconic status. Reader intere ...

of the

conodont Conodonts (Greek ''kōnos'', "cone", + ''odont'', "tooth") are an extinct group of agnathan (jawless) vertebrates resembling eels, classified in the class Conodonta. For many years, they were known only from their tooth-like oral elements, which ...

species ''

Baltoniodus triangularis ''Baltoniodus'' is an extinct genus of conodonts. Use in stratigraphy The base of the Dapingian, the third stage of the Middle Ordovician, is defined as the first appearance of ''Baltoniodus triangularis''. The Whiterock Stage refers mainly ...

'' which happened about million years ago. The Dapingian lasted for about 2.7 million years until about million years ago.Note: there is an apparent typo in the article referenced; they give the coordinates as "a latitude of 30°51’37.8"N and a longitude of 110°22’26.5"E", but their map and location description better corresponds to 30°51’37.8"N 111°22’26.5"E.

History

The Ordovician was divided into three series and six global stages in 1995; in 2005, this was amended to seven stages with the formalization of the

Hirnantian The Hirnantian is the final internationally recognized stage of the Ordovician Period of the Paleozoic Era. It was of short duration, lasting about 1.4 million years, from to Ma (million years ago). The early part of the Hirnantian was charact ...

stage as the last stage in the Late Ordovician. 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 Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them.Hine, Robert. “Biostratigraphy.” ''Oxford Reference: Dictionary of Bi ...

. The conodont ''Baltoniodus triangularis'', a species found in Baltica and China, defined the base of the regional Baltic 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 '' Isograptus v. lunatus'', an abundant worldwide graptolite. The Whiterock Narrows section in the Ninemile Formation of

Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...

was the initial suggestion for the GSSP of the third stage, but a 2001 review of the site revealed that its local conodont fauna was misaligned with wider graptolite zonation. In its place, two formal GSSP candidates were proposed. The Niquivil section of

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

used another widespread species, ''

Protoprioniodus ''Protoprioniodus'' is an extinct genus of conodonts. Use in stratigraphy The Whiterock Stage refers mainly to the early Middle Ordovician in North America. It is often used in the older literature in a global sense. The Whiterock Stage is ...

(Cooperignathus) aranda'', as a proxy for ''B. triangularis'', ''T. laevis'', and graptolites, which were absent from the section. The Huanghuachang section of

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

hosted a more diverse fauna of index fossils, including ''Baltoniodus triangularis'' and biostratigraphically useful graptolites and chitinozoans. The Huanghuachang section was approved as the GSSP for the third stage in 2006, and was ratified by the ICS in 2007.

Naming

The Dapingian is named after Daping, a village that lies near the Dapingian GSSP at Huanghuachang. Daping is very close to an outcrop with similar rocks, the "Chenjiahe section" (formerly "Daping section") in

Chenjiahe Chenjiahe Town () is an urban town in Sangzhi County, Zhangjiajie, Hunan Province, China. Administrative division The town is divided into 20 village A village is a clustered human settlement or community, larger than a hamlet but ...

. The name of the Dapingian stage was introduced in 2007 and approved alongside the stage's ratification, beating out earlier suggestions such as "Volkhovian" and "Huanghuachangian".

GSSP

The Global Boundary Stratotype Section and Point (

GSSP A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted b ...

) of the Dapingian is the Huanghuachang section (), in

Huanghuachang Huanghuachang () is a village in Huanghua, Yiling, Yichang, Hubei, China. An outcrop of sedimentary rock from the Ordovician has made Huanghuachang famous in the earth science community. The "Huanghuachang section" () is an outcrop of the Dawan F ...

Yichang Yichang (), alternatively romanized as Ichang, is a prefecture-level city located in western Hubei province, China. It is the third largest city in the province after the capital, Wuhan and the prefecture-level city Xiangyang, by urban populati ...

. It is an outcrop of the Dawan Formation. The lower boundary is defined as the

of the

species ''

'' in the type section. Radiometric dating has constrained the

-Dapingian boundary at million years ago. The exact boundary lies 10.57 m above the base of Dawan Formation.

Regional stages

The Dapingian overlaps with the upper part of the

Arenig In geology, the Arenig (or Arenigian) is a time interval during the Ordovician period and also the suite of rocks which were deposited during this interval. History The term was first used by Adam Sedgwick in 1847 with reference to the "Areni ...

, a geologic stage used in

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

. It is also equivalent to the lower part of the North American

Whiterockian The Whiterockian, often referred to simply as the Whiterock, is an earliest or lowermost stage of the Middle Ordovician. Although the Whiterockian or Whiterock Stage refers mainly to the early Middle Ordovician in North America, it is often used in ...

stage, most of the Baltic/Russian

Volkhov Volkhov (russian: Во́лхов) is an industrial town and the administrative center of Volkhovsky District in Leningrad Oblast, Russia, located on the river Volkhov east of St. Petersburg. Population: It was previously known as ''Zvanka ...

stage, and the Castlemainian and Yapeenian stages which have been used in Australia and Scandinavia.

References

{{Geological history, p, p, state=collapsed * Ordovician geochronology