The Cambrian period ended with a mass extinction event approximately 485 million years ago. This event was the first of the five major extinction events that have occurred in Earth's history, and it resulted in the extinction of around 50% of all marine species.

The cause of the Cambrian extinction event is not fully understood, but it is thought to have been caused by a combination of factors, including a rapid decrease in sea level, a decrease in oxygen levels in the oceans, and a change in global climate.

The Cambrian extinction event had a profound impact on the evolution of life on Earth. It cleared the way for the emergence of new organisms, including the ancestors of all vertebrates, and it set the stage for the diversification of life that occurred during the subsequent periods.