Chicxulub Impact

Definition

The Chicxulub Impact refers to a massive asteroid collision that occurred around 66 million years ago, resulting in the formation of the Chicxulub crater located on the Yucatán Peninsula in Mexico. This event is widely believed to have triggered the Cretaceous-Paleogene (K-Pg) mass extinction, which led to the dramatic decline of many species, including the non-avian dinosaurs. The impact had far-reaching effects on Earth's biodiversity and climate, reshaping life on the planet.

5 Must Know Facts For Your Next Test

1. The Chicxulub crater is about 150 kilometers in diameter and was created by an estimated 10-kilometer-wide asteroid striking Earth at high velocity.
2. The impact caused immediate and catastrophic environmental changes, including massive wildfires, tsunamis, and a 'nuclear winter' effect from debris blocking sunlight.
3. Evidence of the Chicxulub Impact can be found in geological layers around the world, with a distinct layer of iridium-rich clay marking the K-Pg boundary.
4. The extinction event resulted in the disappearance of approximately 75% of Earth's species, allowing mammals and birds to become the dominant terrestrial animals in subsequent eras.
5. Research indicates that other factors, such as volcanic activity from the Deccan Traps in India, may have also contributed to the mass extinction alongside the Chicxulub Impact.

Review Questions

• How did the Chicxulub Impact contribute to the mass extinction event at the end of the Cretaceous period?
  • The Chicxulub Impact played a crucial role in triggering the mass extinction at the end of the Cretaceous period by causing catastrophic environmental changes. The collision released enormous amounts of energy, resulting in wildfires, tsunamis, and significant atmospheric disturbances. These events led to drastic climate shifts and a prolonged 'nuclear winter' scenario, where sunlight was blocked by debris, disrupting photosynthesis and leading to food chain collapse.
• Discuss how evidence from geological layers supports the occurrence of the Chicxulub Impact and its effects on global biodiversity.
  • Geological evidence supporting the Chicxulub Impact includes a distinct layer of iridium-rich clay found at various sites worldwide, marking the K-Pg boundary. This layer suggests a sudden increase in iridium concentration linked to extraterrestrial sources. Additionally, fossil records indicate a sharp decline in species diversity right after this boundary, providing further support that this impact led to a widespread mass extinction event affecting global biodiversity.
• Evaluate the broader implications of the Chicxulub Impact on evolutionary trajectories following the Cretaceous-Paleogene extinction event.
  • The Chicxulub Impact significantly altered evolutionary trajectories by wiping out approximately 75% of Earth's species, including dominant groups like dinosaurs. This mass extinction opened ecological niches that allowed mammals and birds to thrive and diversify in the absence of their competitors. The event set the stage for modern ecosystems by promoting rapid evolutionary adaptations and diversification among surviving species during the Paleogene period.

Related terms

Mass Extinction: A significant and rapid decrease in biodiversity on Earth, where a large number of species become extinct over a relatively short period.

Cretaceous-Paleogene Boundary: The geological marker that indicates the end of the Cretaceous period and the beginning of the Paleogene period, coinciding with the Chicxulub impact.

Impact Hypothesis: The theory proposing that a catastrophic impact event, such as the Chicxulub impact, was responsible for the mass extinction at the end of the Cretaceous period.