Cretaceous-Paleogene Extinction

Definition

The Cretaceous-Paleogene extinction, often referred to as the K-Pg extinction event, marks a significant mass extinction that occurred approximately 66 million years ago. This event is most famously known for the dramatic loss of around 75% of Earth's species, including the dinosaurs, and is widely believed to have been caused by a combination of a massive asteroid impact and extensive volcanic activity, leading to major climatic changes.

5 Must Know Facts For Your Next Test

1. The Cretaceous-Paleogene extinction event occurred around 66 million years ago and is one of the five major mass extinctions in Earth's history.
2. It is estimated that more than 75% of all species, including all non-avian dinosaurs, went extinct during this event.
3. Evidence suggests that the primary causes of this extinction were a combination of a massive asteroid impact and extensive volcanic activity from the Deccan Traps.
4. The aftermath of the K-Pg extinction led to significant changes in Earth's climate, including drastic cooling and alterations in ecosystems.
5. This mass extinction paved the way for mammals to rise and diversify, ultimately leading to the dominance of mammals in the Cenozoic Era.

Review Questions

• What were the main causes of the Cretaceous-Paleogene extinction, and how did they contribute to such a massive loss of biodiversity?
  • The main causes of the Cretaceous-Paleogene extinction include a massive asteroid impact that created the Chicxulub Crater and extensive volcanic activity from the Deccan Traps. The asteroid impact is believed to have generated enough heat and energy to cause fires, tsunamis, and eject debris into the atmosphere, blocking sunlight and disrupting photosynthesis. Meanwhile, the volcanic eruptions released vast amounts of gases like sulfur dioxide and carbon dioxide, leading to acid rain and significant climate change. Together, these events created an inhospitable environment for many species, resulting in widespread extinction.
• Discuss how the Cretaceous-Paleogene extinction event illustrates the interconnectedness of geological events and biological evolution.
  • The Cretaceous-Paleogene extinction event exemplifies how geological phenomena, such as asteroid impacts and volcanic eruptions, can drastically alter Earth's environment and directly affect biological evolution. The significant environmental shifts that occurred after these events resulted in the extinction of numerous species, which allowed other organisms, particularly mammals, to thrive in their absence. This shift highlights the dynamic relationship between Earth's geological processes and evolutionary pathways, as new opportunities arise following mass extinctions.
• Evaluate the long-term effects of the Cretaceous-Paleogene extinction on Earth's biodiversity and ecological systems during subsequent eras.
  • The long-term effects of the Cretaceous-Paleogene extinction on Earth's biodiversity were profound and set the stage for new ecological systems during subsequent eras. The extinction opened ecological niches that allowed mammals to diversify and become dominant in many environments. Over millions of years, this led to a rich variety of life forms, including primates and ultimately humans. Additionally, it changed predator-prey relationships and ecosystem structures, showcasing how mass extinctions can reshape life's evolutionary trajectory and contribute to the development of new species.

Related terms

Chicxulub Crater: A large impact crater located on the Yucatán Peninsula in Mexico, formed by the asteroid that is thought to have triggered the Cretaceous-Paleogene extinction.

Deccan Traps: A large volcanic province in India, created by volcanic eruptions that occurred around the same time as the K-Pg extinction, contributing to significant environmental changes.

Mass Extinction: A rapid and widespread decrease in biodiversity on Earth, typically defined as an event where at least 75% of species are lost in a relatively short geological time frame.