Kasimovian

The Kasimovian is a special time in Earth's history. It is part of the ICS geologic timescale. The Kasimovian happened during the late Carboniferous period.

This time came after the Moscovian and before the Gzhelian. During the Kasimovian, big changes happened to plants and animals because of something called the Carboniferous Rainforest Collapse.

In North America, this time is called the Missourian. In western Europe, it is known as the Stephanian. Learning about the Kasimovian helps us understand how Earth’s climate and life have changed over many years.

Name and definition

The Kasimovian is named after the Russian city of Kasimov. A scientist called Boris Dan'shin defined this time period in 1926 and first called it the Teguliferina horizon. After Dan'shin died, the name was changed to Kasimov horizon. In 1949, it became known as the Kasimovian.

The start of the Kasimovian is marked by certain fossils. These include special types of fusulinid biozone and the first appearance of an ammonite genus. The end of this stage is also marked by new fossils. These include specific fusulinids and the conodont Streptognathodus zethus.

Biozones

The Kasimovian time period has three special layers. We learn about them from tiny, ancient teeth called conodonts. These layers are:

• Idiognathodus toretzianus Zone
• Idiognathodus sagittatus Zone
• Streptognathodus excelsus and Streptognathodus makhlinae Zone