EndOrdovisian

The EndOrdovisian is a period of Earth's history marking the boundary between the Ordovician and Silurian geological periods. This boundary is defined by a significant extinction event, the Ordovician-Silurian extinction, which occurred approximately 443.8 million years ago. This extinction event is one of the largest in Earth's history, significantly reducing the diversity of marine life.

The EndOrdovisian is characterized by rapid environmental changes that led to the extinction. The prevailing theory suggests a period of intense glaciation, known as the Hirnantian glaciation, caused sea levels to drop dramatically. This drop in sea level would have devastated shallow marine ecosystems, which were home to a vast array of life. Following the glaciation, a rapid warming period and subsequent sea-level rise may have also contributed to the extinctions, possibly through anoxic events.

Before this extinction, life in the oceans was thriving and diverse, with brachiopods, trilobites, cephalopods, and early jawless fish being particularly abundant. The EndOrdovisian extinction drastically altered the composition of these communities. Many groups that had flourished during the Ordovician, such as certain types of trilobites and graptolites, were severely impacted. However, some groups, like corals and cephalopods, eventually recovered and continued to evolve. The event paved the way for new evolutionary radiations in the subsequent Silurian period.