Cambrian Stage 2

Stage 2 of the Cambrian is an important time in Earth's history. It is the upper stage of the Terreneuvian Series. It comes after the Fortunian stage and before Stage 3 of the Cambrian. This stage is often called the Tommotian, named after rock layers in Siberia.

Scientists have not set official dates for when Stage 2 began or ended. However, many think it started when early animals, like the molluscs Watsonella crosbyi and Aldanella attleborensis, first appeared, about 529 million years ago. These animals help us learn when this stage began.

Some believe the end of Stage 2 might be marked by the first appearance of trilobites, around 521 million years ago. Studying these ancient layers helps us understand how life on Earth began to change and grow long ago.

Naming

The name "Laolinian" was proposed for Stage 2 of the Cambrian in 2012. It is named after Laolin village in Yunnan, China.

Stratotype

Scientists are trying to find a special point in rock layers to mark the start of Cambrian Stage 2. One idea is to use the first appearance of a tiny shell creature called Watsonella crosbyi in rocks from the Zhujiaqing Formation in Yunnan, China. Another idea is to use a layer found near the Aldan River on the Siberian Platform. These places help experts learn about the very beginning of this important time in Earth's history.