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How did a large impact at the end of the Cretaceous Period contribute to the extinction of dinosaurs?
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Meteor and meteoroid
The Cabin Creek meteorite, an iron (nickel-iron alloy) meteorite that was observed to fall in northwestern Arkansas on March 27, 1886. Its characteristic pattern of “thumbprint” dimples, or regmaglypts, is the result of melting and consequent ablation of its surface as it traveled through the atmosphere. The meteorite is likely a fragment of one of the M class asteroids, which show significant nickel-iron in their surface material.
The extinction of the dinosaurs at the end of the Cretaceous Period is widely attributed to the impact of a large asteroid or comet, approximately 10 km (6 miles) in diameter, which struck Earth near present-day Chicxulub, Mexico.123
According to the Alvarez theory, this massive impact triggered a global mass extinction event through several catastrophic environmental consequences:142
- Atmospheric Disruption: The impact ejected a massive quantity of rock debris into the atmosphere, creating a global dust cloud that enshrouded Earth in darkness for several months or longer.12
- Collapse of the Food Chain: The lack of sunlight prevented photosynthesis, leading to the death of green plants and the subsequent collapse of the food chain.12
- Secondary Effects: The impact also triggered widespread wildfires and an enormous tsunami in the Gulf of Mexico.12
While this impact is a primary explanation, some scientists suggest that terrestrial factors—such as massive volcanic activity known as the Deccan Traps and continental drift—may have also contributed to environmental deterioration during this period.12