Essay 5 - Earth and Life The Chicxulub Impact changed dramatically the course of

Question

Essay 5 - Earth and Life

The Chicxulub Impact changed dramatically the course of life on this planet. It's estimated that over 75% of all species, most notably all of the non-avian dinosaurs, were wiped out by the event. Though the 10 km impactor left behind a large, complex impact crater at the site, the impact itself wasn't all that big. If the crater were placed on any other heavily cratered world, you'd have a hard time picking it out as anything extraordinary. Sure it would have been a very bad day for life in the general vicinity of the impact, but for biology half a world away it would have been just another day. (1) Explain why then, did this particular event, cause the global extinction of over 75% of all species on this planet? I'm not asking for a detailed description of the events leading up to the demise of the dinosaurs, I'm asking for you to explain what is unique about this situation that led to this much carnage. HINT: comparing this to another terrestrial world my be helpful in guiding your discussion.

Explanation / Answer

A group of researchers found that the Cretaceous-Paleogene extinction, the episode that washed out around 75% of the planet’s species, including approximately all dinosaur was caused by an asteroid collision in Mexico 66 million years ago. The Cretaceous–Paleogene extermination was the last great extinction incident to occur on Earth, and is most distinguished for causing the diversification of mammals that finally resulted in Homo sapiens.

66 million years ago an asteroid around 15 kilometers wide hit into Chicxulub, Mexico. The collision, caused a 180-kilometer crater and released 430 zetta joules of energy, or almost two million times stronger than the largest thermonuclear device ever used. The collision created a large dust cloud which blocked out the Sun and starting the extinction ball rolling by killing most of the world’s plants, and thus the herbivores soon after. Because of the high levels of oxygen in the Cretaceous atmosphere, the collision may also have created powerful, global firestorms which killed off many other species. Because the asteroid landed in the ocean, mega tsunamis would have also cleared the world’s coasts.

There has not been enough evidence that the Chicxulub impact actually caused the Cretaceous-Paleogene destruction until now. There was definitely a huge asteroid impact, but earlier proof showed that the asteroid impact occurred up to around 300,000 years before the destruction of the dinosaurs.

Now, scientists have re-experiment the remains from Chicxulub using equipment and pointed to the asteroid impact down to a period of 11,000 years, between 66.03 and 66.04 million years ago approximately synchronized with the Cretaceous-Paleogene extinction. As the research paper puts it, though, “the Chicxulub collision likely generated a state of shift of ecosystems already under a near-critical strain.” In other words, prior to the extinction event, Earth was already staggering on the edge of self-annihilation.

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