Drumian

The Drumian is an important time period in Earth's history. It is a stage of the Miaolingian Series of the Cambrian period, which is famous for its many fossils and changes in life on our planet. The Drumian comes after the Wuliuan stage and before the Guzhangian stage.

Scientists mark the beginning of the Drumian stage by looking for a special kind of ancient sea creature called a trilobite. Specifically, they look for the first appearance of a trilobite named Ptychagnostus atavus, which lived about 504.5 million years ago. The end of the Drumian is marked by the first appearance of another trilobite, Lejopyge laevigata, around 500.5 million years ago.

Studying the Drumian helps us understand how life evolved during this exciting time in Earth's past. Fossils from this period show us many new and diverse forms of ancient marine life, giving clues about how ecosystems developed long before humans existed.

GSSP

The GSSP is defined in the Drumian section in the Drum Mountains, Millard County, Utah, United States. This area is named after the Drum Mountains and contains layers of rock called the Wheeler Formation. The start of the Drumian stage is marked by a specific layer of limestone found within these rock layers.

Major events

The Drumian stage saw an important change called the Cambrian Drumian carbon isotope excursion (DICE). This change happened when deep waters with low oxygen levels moved closer to the surface. This made it hard for reef ecosystems to recover after earlier extinctions during the Cambrian period. Later in the Drumian stage, there was a time when many sea creatures began to appear more often before another extinction event occurred.

Paleontology

The Drumian stage is known for its many fossils of ancient sea creatures. Scientists have found remains of sponges, palaeoscolecids, and euarthropods, which include large, unusual animals called radiodonts. These fossils help us understand what life was like in the ocean millions of years ago during this time.