| Miaolingian | ||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| ~506.5 – ~497Ma | ||||||||||||||||||||||||||||||||||||||
.png) A map of Earth as it appeared 505 million years ago during the Miaolingian Series, Wuliuan Stage | ||||||||||||||||||||||||||||||||||||||
| Chronology | ||||||||||||||||||||||||||||||||||||||
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| Etymology | ||||||||||||||||||||||||||||||||||||||
| Name formality | Formal | |||||||||||||||||||||||||||||||||||||
| Name ratified | June 25, 2018[2] | |||||||||||||||||||||||||||||||||||||
| Former name(s) | Cambrian Series 3 | |||||||||||||||||||||||||||||||||||||
| Usage information | ||||||||||||||||||||||||||||||||||||||
| Celestial body | Earth | |||||||||||||||||||||||||||||||||||||
| Regional usage | Global (ICS) | |||||||||||||||||||||||||||||||||||||
| Time scale(s) used | ICS Time Scale | |||||||||||||||||||||||||||||||||||||
| Definition | ||||||||||||||||||||||||||||||||||||||
| Chronological unit | Epoch | |||||||||||||||||||||||||||||||||||||
| Stratigraphic unit | Series | |||||||||||||||||||||||||||||||||||||
| Time span formality | Formal | |||||||||||||||||||||||||||||||||||||
| Lower boundary definition | FAD of theTrilobiteOryctocephalus indicus. | |||||||||||||||||||||||||||||||||||||
| Lower boundary GSSP | Wuliu-Zengjiayan,Guizhou,China 26°44.843′N108°24.830′E / 26.747383°N 108.413833°E /26.747383; 108.413833 | |||||||||||||||||||||||||||||||||||||
| Lower GSSP ratified | June 25, 2018[2] | |||||||||||||||||||||||||||||||||||||
| Upper boundary definition | FAD of the TrilobiteGlyptagnostus reticulatus | |||||||||||||||||||||||||||||||||||||
| Upper boundary GSSP | Paibi section,Paibi,Hunan,China 28°23.37′N109°31.54′E / 28.38950°N 109.52567°E /28.38950; 109.52567 | |||||||||||||||||||||||||||||||||||||
| Upper GSSP ratified | 2003[3][4] | |||||||||||||||||||||||||||||||||||||
TheMiaolingian is the third Series of theCambrian Period, and was formally named in 2018.[2] It lasted from about 506.5 to 497 million years ago and is divided in ascending order into 3 stages: theWuliuan,Drumian, andGuzhangian. The Miaolingian is preceded by the unnamedCambrian Series 2 and succeeded by theFurongian series.[5]
It is named after theMiaoling Mountains in southeasternGuizhou Province,China.[6]
A number of proposals for fossils and type sections were made before it was formally ratified in 2018. The most promising fossil markers were seen to be the respective first appearances of either trilobite speciesOvatoryctocara granulata orOryctocephalus indicus,[7] which both have an age close to 506.5 million years ago.[5] After some deliberation, the FAD ofOryctocephalus indicus was chosen to be the lower boundary marker, and the GSSP was placed in theKaili Formation,Wuliu-Zengjiayan,Guizhou,China.[6][8]
The Miaolingian-Furongian boundary has the same definition as thePaibian Stage. It is defined as the first appearance ofGlyptagnostus reticulatus around 497 million years ago.[5]
The Miaolingian is subdivided into the following stages:[5]
| Epoch / Series | Age / Stage | Age lower boundary (mya) |
|---|---|---|
| Furongian | ||
| Stage 10 | 491 | |
| Jiangshanian | 494.2 | |
| Paibian | 497 | |
| Miaolingian | ||
| Guzhangian | 500.5 | |
| Drumian | 504.5 | |
| Wuliuan | 506.5 | |
| Series 2 | ||
| Stage 4 | 514.5 | |
| Stage 3 | 521 |
The Ordian stage, which is use in Australian chronostratigraphical scale, was originally supposed to be the lowest stage of the Miaolingian, but may belong to upper Series 2. As of 2024, the base of the Ordian is not defined yet.[9]
At theCambrian Series 2–Miaolingian boundary, the first majortrilobite extinction, known as theOlenellid Biomere boundary, occurred. In particular, trilobites of the familiesOllenellidae andRedlichiidae have been extinct inLaurentia and South China, respectively.[10] The firstO. indicus appear after this global extinction, and in areas whereO. indicus fossils are absent, the Series 2–Miaolingian boundary is determined bychemostratigraphic data.[11]
Benthicgraptolites have reached a wide distribution in the Miaolingian. Encrusting colonies of theRhabdopleuridae and erect growing branching colonies of theDithecodendridae families evolved already at the beginning of the Miaolingian. The most commonWuliuan graptolite genus isSphenoecium, whose robust colonies were found all over the world.[12]
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