Cambrian Stage 10

Stage 10 of the Cambrian is the last part of the Furongian series. It comes after the Jiangshanian and before the Ordovician's Tremadocian Stage. Scientists use a special trilobite called Lotagnostus americanus to mark the start of this stage, which began about 491 million years ago. They also study other fossils to help define this time. The end of Stage 10 is marked by a conodont named Iapetognathus fluctivagus, which signals the start of the Tremadocian about 486.85 million years ago. This stage helps us understand changes in life on Earth from long ago.

Naming

The 10th stage of the Cambrian has not yet received an official name from the ICS. Some scientists use local names. One suggestion is to call it the "Lawsonian," named after Lawson Cove in the Wah Wah Mountains in Utah. Another name is the Skullrockian Stage, used in North America. In 2011, a third name, "Nelegerian," was proposed, named after the Neleger River in Yakutia.

Stratotype

The ICS is still choosing a location to mark the start of the 10th Cambrian stage.

One idea was a site near Duibian in Zhejiang, China. Now, many experts like Steamboat Pass in the House Range of Utah. If they use a special ancient creature called a conodont, many places could work, like sites in Australia, Kazakhstan, and Canada. Scientists are studying different ancient animals, such as the trilobite Lotagnostus americanus or conodonts like Cordylodus andresi and Eoconodontus notchpeakensis, to find the best mark for this stage. The appearance of Eoconodontus notchpeakensis is popular because it is found all over the world and does not change much in different places.

Subdivisions

Cambrian Stage 10 can be split into smaller parts using fossils. Scientists study special types of conodonts and trilobites. These fossils help us learn about the order of rock layers and what life was like back then.