Jiangshanian

The Jiangshanian is an important time period in Earth's history. It is the middle part of the Furongian series, which belongs to the early part of the Cambrian period, a time when many early animals first appeared. The Jiangshanian comes after the Paibian Stage and is followed by an unnamed stage called Stage 10.

This stage is defined by the first appearance of a special kind of trilobite called Agnostotes orientalis. Scientists estimate this happened about 494.2 million years ago. The Jiangshanian period lasted until around 491 million years ago.

The name Jiangshanian comes from the city of Jiangshan in Zhejiang province, China. This is where scientists chose to define this important time in Earth's past, helping us understand how life developed long ago.

Stratigraphy

The Jiangshanian is a middle stage of the Furongian series in Earth's history. It comes after the Paibian Stage and before Stage 10 of the Cambrian.

This stage began when a type of ancient sea creature called a trilobite first appeared. Scientists think this happened about 494.2 million years ago.

Researchers study this stage in many places around the world. One important place is near a village called Duibian, west of the town of Jiangshan. Another place is in southern Kazakhstan, near a river called Kyrshabakty. These places help scientists learn about the rock layers from this time.

Major events

At the start of the Jiangshanian time period, many different species lived, similar to what was seen in the middle of the Guzhangian. Later, a period called the Jiangshanian extinction happened. This event lasted from about 493.9 to 491.3 million years ago. It caused a big drop in the number of species. After this, there were small changes in the number of species until the beginning of the Ordovician period.

Paleontology

Scientists found about 50 kinds of very old life in the Jiangshanian time layer in Guangxi, in South China. These fossils include simple plants called algae, tiny sea animals named graptolites, and many small sea creatures like arthropods. They also found rare fossils in places like Poland.

In other areas, such as western Tasmania and the Wichita Mountains in Oklahoma, USA, scientists found fossils of trilobites. These were small sea animals with hard shells. Many kinds of trilobites have been found from this time.