Cisuralian

The Cisuralian, also known as the Early Permian, was the first series/epoch of the Permian. It came after the Pennsylvanian and was followed by the Guadalupian. This important time period is named after the western slopes of the Ural Mountains in Russia and Kazakhstan, and it lasted from about 298.9 million to 274.4 million years ago.

During the Cisuralian, significant changes occurred in the animal world. For the first time, beetles and flies appeared, marking an important step in the development of insects. The climate during this epoch was relatively stable and warm, spanning roughly 21 million years. This period played a key role in the evolution of life on Earth and helped shape the ecosystems that came after it.

Name and background

The Cisuralian is the first part of the Permian period. It came after the Pennsylvanian epoch (Gzhelian) and was followed by the Permian Guadalupian Epoch.

The name "Cisuralian" comes from the western slopes of the Ural Mountains in Russia and Kazakhstan. It was suggested in 1982 and approved in 1996. Limestones from this time make up the Ishimbay oil fields, which were important to the Soviet Union during World War II. The start of the Cisuralian is marked by the appearance of a specific fossil called Streptognathodus isolatus, and the global reference point for this is near Aqtöbe in Kazakhstan.

Geography

Gondwana collided with Laurussia, forming the Alleghenian orogeny in what is now North America. In northwestern Europe, the Hercynian orogeny continued. By the middle of the early Permian, these events created the large supercontinent Pangea, which had a big impact on the climate.

Climate

At the start of the Permian period, the Late Palaeozoic Ice Age was at its peak. Glaciers slowly receded as the Earth's climate began to warm, especially during an event called the Artinskian Warming. This warming made the interiors of continents much drier, especially in the tropical areas of Pangaea.

Biodiversity

During the Cisuralian period, the edges of swamps were filled with ferns, seed ferns, and lycophytes, while beetles and flies began to appear for the first time. Some older plant-eating animals like Diadectes and Edaphosaurus were still around, and new creatures such as Caseids and Tetraceratops showed up.

The oceans were busy with many types of sea life, including unusual sharks like Helicoprion. On land, animals called pelycosaurs, which include famous species like Dimetrodon, were the main rulers. These early synapsids had been around since the Late Carboniferous and stayed on top for about 40 million years before being replaced by therapsids.

Subdivisions

The Cisuralian, also called the Early Permian, is split into four main global stages: the Asselian from about 299 to 295 million years ago, the Sakmarian from about 295 to 290 million years ago, the Artinskian from about 290 to 284 million years ago, and the Kungurian from about 284 to 272 million years ago.

Some places, like New Zealand, use different names for this time. They call the period from 289 to 278 million years ago the Telfordian, and from 278 to 270.6 million years ago the Mangapirian.