| System (period) | Series | Stage (age) | Lower boundary, Ma | |
|---|---|---|---|---|
| Ordovician | Lower | Tremadocian | 485.4±1.9 | |
| Cambrian | Furongian | Stage 10 | ~489.5 | |
| Jiangshanian |  ~494
| |||
| Paibian | ~497
| |||
| Miaolingian | Guzhangian | ~500.5
| ||
| Drumian | ~504.5
| |||
| Wuliuan | ~509
| |||
| Series 2 | Stage 4 | ~514 | ||
| Stage 3 | ~521 | |||
| Terreneuvian | Stage 2 | ~529 | ||
| Fortunian | 538.8±0.2
| |||
| Ediacaran | older | |||
| Subdivisions and "golden spikes" according to IUGS as of September 2023[1] | ||||
The Guzhangian is a third and upper stage of the Miaolingian series, corresponding to the Guzhangian age of the Miaolingian epoch. It lasted from approximately 500.5 Ma to around 497 Ma (million years ago). It is preceded by the Drumian age of the Miaolingian and is followed by the Paibian age of the Furongian. In the middle of the Guzhangian, the extinction of some benthic organisms, probably caused by the depletion of oxygen in the ocean, began.
Guzhangian partially coincides with the less voluminous Ayusokkanian stage, which is used in the stratigraphic chart of Kazakhstan and Siberia. It also correspond to Boomerangian and Mindyallan stages of the regional Australian chart.
Definition[]
The GSSP of the Guzhangian stage was ratified in 2008. The lower boundary is fixed 121.3 m above the base of the Huaqiao Formation in Louyixi, Guzhang County, Hunan Province, South China, and related to the first appearance of agnostoid arthropod Lejopyge laevigata.[2]
Guzhangian life[]
Micromitra
Acontheus
Paradoxides
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Agnostus pisiformis
The continents remained deserted, and life developed mainly in the seas. Hexactinellid sponges (Ratcliffespongia, Kiwetinokia, Valospongia, Silicunculus), brachiopods (Micromitra, Canalilatus, Linnarssonia, Anabolotreta) and helcionelloid molluscs (Obtusoconus, Protowenella, Anabarella, Latouchella) lived on the seabed. Rostroconchs (Tuarangia, Ribeiria, Apoptopegma) and priapulid worms such as Ottoia lived in the near-surface soil. Among arthropods, trilobitomorphs reached large numbers. Trilobites were predominantly benthic animals that fed on detritus. Several orders of these animals existed at that time. Lichid (Meringaspis, Stephanocare, Teinistion, Blackwelderia), olenid (Andrarina, Lisania), ptychopariid (Lisaniella, Pianaspis, Maotunia, Agelagma), corynexochid (Acontheus, Aedotes, Meropalla, Fuchouia), redlichiid (Centropleura, Paradoxides, Agraulos, Tangshihlingia) and asaphid (Leichneyella, Rhyssometopus, Griphasaphus, Tasmana) trilobites are known from this stage. Their most numerous relatives were agnostids, smaller animals that probably lived both at the bottom and in the water column. Guzhangian genera include Agnostus, Ptychagnostus, Gonoagnostus, Onymagnostus, Utagnostus and Acidusus. Ostracods like Aristaluta inhabited seas. Anomalocaridids were probably extinct by this time. Youngest species found in rocks of approximately this age include Anomalocaris canadensis and a few unidentified specimens.
Numerous conodonts or their relatives (Westergaardodina, Furnishina, Gapparodus, Phakelodus) have been found in Guzhangian Huaqiao Formation in Hunan, China.
References[]
- ↑ "Latest version of international chronostratigraphic chart". International Commission on Stratigraphy. https://stratigraphy.org/chart#latest-version.
- ↑ "GSSP Table - Paleozoic Era". https://timescalefoundation.org/gssp/index.php?parentid=77.