Silurian-Devonian extinction event

Definition

The Silurian-Devonian extinction event refers to a significant biological crisis that occurred around 419 million years ago, marking a period of substantial loss of biodiversity between the Silurian and Devonian periods. This extinction event resulted in the decline of various marine organisms, including some groups of trilobites and reef builders, while paving the way for new life forms to thrive in the subsequent Devonian period, often called the 'Age of Fishes'.

5 Must Know Facts For Your Next Test

1. The Silurian-Devonian extinction event is considered one of the five major mass extinctions in Earth's history, impacting marine life significantly.
2. It is believed that changes in sea level and climate, as well as possibly asteroid impacts, contributed to the environmental stress that caused this extinction.
3. The event led to a dramatic reduction in reef-building organisms, which altered marine ecosystems and paved the way for new types of marine life in the Devonian.
4. Following this extinction event, there was an evolutionary radiation of fish, with the Devonian period seeing the rise of many modern fish groups.
5. Some evidence suggests that this extinction may have been prolonged over several million years rather than occurring as a single abrupt event.

Review Questions

• How did the Silurian-Devonian extinction event affect marine biodiversity?
  • The Silurian-Devonian extinction event caused a significant loss of marine biodiversity by leading to the decline of various groups such as trilobites and certain reef builders. This loss altered the existing marine ecosystems and reduced competition for resources. The resulting environmental shifts allowed for the emergence and diversification of new species in the following Devonian period.
• Discuss the potential causes of the Silurian-Devonian extinction event and their impact on Earth's environment.
  • The Silurian-Devonian extinction event likely had multiple causes including climatic changes, fluctuations in sea level, and possibly asteroid impacts. These factors created harsh conditions for many marine organisms, disrupting habitats and food chains. The result was a significant turnover in species composition, which profoundly reshaped marine environments and influenced evolutionary trajectories.
• Evaluate the long-term effects of the Silurian-Devonian extinction event on the evolution of life during the Devonian period.
  • The long-term effects of the Silurian-Devonian extinction event were critical in shaping the evolution of life during the Devonian period. The loss of dominant species created ecological niches that allowed other organisms to thrive, particularly fish which experienced significant diversification. This period is often referred to as the 'Age of Fishes' due to this explosion in fish diversity, setting the stage for future developments in vertebrate evolution and ultimately leading towards terrestrial colonization by amphibians.

Related terms

Biodiversity: The variety of life in the world or in a particular habitat or ecosystem, which includes the diversity of species, genetic variations, and ecosystems.

Trilobites:

An extinct group of marine arthropods that were prominent during the Paleozoic Era, known for their three-lobed body structure.

Devonian period: A geological period that lasted from about 419 to 359 million years ago, known for significant evolutionary advancements in fish and the first appearance of amphibians.