Cambrian Stage 2

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

Scientists have not yet set official dates for the beginning or end of Stage 2. However, many believe it started when certain early animals, like the molluscs Watsonella crosbyi and Aldanella attleborensis, first appeared, about 529 million years ago. These animals are important clues for figuring out when this stage began.

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

Naming

The name "Laolinian" was suggested for Stage 2 of the Cambrian in 2012. It comes from Laolin village in Yunnan, China.

Stratotype

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