Cambrian explosion

Definition

The Cambrian explosion refers to a significant period in Earth's history, approximately 541 million years ago, marked by a rapid increase in the diversity of life forms and the emergence of many major animal groups. This event is characterized by the appearance of complex organisms with hard body parts and various body plans, laying the groundwork for future evolutionary developments in marine ecosystems.

5 Must Know Facts For Your Next Test

1. The Cambrian explosion lasted for about 20 million years, during which most major animal phyla first appeared in the fossil record.
2. This event is thought to have been triggered by several factors, including increased oxygen levels, changes in ocean chemistry, and ecological interactions among species.
3. Many iconic fossils from the Cambrian explosion display unique features such as segmentation and exoskeletons, which contributed to their survival and adaptability.
4. The Cambrian explosion also set the stage for the development of modern animal phyla, influencing evolutionary paths that persist today.
5. Research on the Cambrian explosion has been crucial for understanding the origins of biodiversity and the evolutionary history of life on Earth.

Review Questions

• What factors are believed to have contributed to the rapid diversification of life during the Cambrian explosion?
  • Several factors likely contributed to the rapid diversification during the Cambrian explosion, including increased oxygen levels that supported larger and more complex organisms, changes in ocean chemistry that may have created new ecological niches, and predator-prey interactions that drove evolutionary adaptations. These factors combined to create an environment conducive to innovation in body plans and functional adaptations among marine life.
• How do fossils from the Burgess Shale enhance our understanding of the Cambrian explosion?
  • Fossils from the Burgess Shale provide critical insights into the diversity and complexity of life during the Cambrian explosion. This fossil site contains exceptionally preserved specimens that showcase a wide range of body forms and structures not seen before this period. Studying these fossils allows scientists to reconstruct ancient ecosystems and understand how early organisms interacted with each other and their environments.
• Evaluate the significance of the Cambrian explosion in shaping the trajectory of evolutionary history on Earth.
  • The Cambrian explosion holds immense significance in evolutionary history as it marks a pivotal moment when most major animal phyla emerged, establishing foundational body plans and ecological roles that would influence subsequent evolution. This event not only increased biodiversity but also introduced complex interactions within ecosystems, setting a precedent for future evolutionary developments. The diversity established during this time paved the way for later terrestrial life forms and continues to impact modern ecosystems.

Related terms

Burgess Shale:

A famous fossil site in Canada that provides a wealth of information about the diverse organisms that lived during the Cambrian period, showcasing some of the earliest known complex life forms.

Ediacaran biota: A group of prehistoric multicellular organisms that existed before the Cambrian explosion, providing insights into the early development of complex life on Earth.

Trilobites: Extinct marine arthropods that flourished during the Cambrian period, known for their distinctive three-lobed bodies and significant role in marine ecosystems.