Miaolingian

The Miaolingian or Mid-Late Cambrian is the third part of the Cambrian Period. It was named in 2018. It lasted from about 506.5 to 497 million years ago. It has three stages: the Wuliuan, Drumian, and Guzhangian.

The Miaolingian comes after the Cambrian Series 2 and is followed by the Furongian series. It is named after the Miaoling Mountains in southeastern Guizhou Province, China. Studying this time helps scientists understand how life changed during the Cambrian Explosion, when many new animals first appeared in the oceans.

Definition

Before 2018, scientists talked about different fossils to mark the start of this time. Two trilobite fossils, Ovatoryctocara granulata and Oryctocephalus indicus, were looked at. They appeared close to 506.5 million years ago. Scientists picked Oryctocephalus indicus. They found it in rocks called the Kaili Formation in Wuliu-Zengjiayan, Guizhou, China.

The end of the Miaolingian is marked by a trilobite fossil named Glyptagnostus reticulatus. It showed up around 497 million years ago. This same fossil also marks the start of the next time, the Furongian, and is linked to the Paibian Stage.

Subdivision

The Miaolingian has three main parts: the Wuliuan, Drumian, and Guzhangian. Before this time, there was a stage called the Ordian, mostly used in Australia. Scientists are still learning if it is part of the Miaolingian or the time before it.

Major events

When the Cambrian Series 2 ended and the Miaolingian began, many ancient sea creatures called trilobites went extinct. This happened to types of trilobites from the families Ollenellidae and Redlichiidae in places like Laurentia and South China. After this, a new trilobite named O. indicus appeared. In areas without O. indicus fossils, scientists use special chemical data to find this time in Earth's history.

Paleontology

During the Miaolingian time period, graptolites—small animals that lived in the ocean—spread widely across the seas. Two families of graptolites, called Rhabdopleuridae and Dithecodendridae, began to evolve early in this period. One common graptolite from the Wuliuan stage was Sphenoecium. It was known for its strong colonies found around the world.