Q How did dinosaurs go extinct?

— Caleb Sanders

A Dave Lovelace, research scientist at the University of Wisconsin-Madison Geology Museum:

When it comes to dinosaur extinction, the working idea is what’s called the bolide impact. This is the hypothesis that a meteorite came to the surface of the Earth, hit the Earth and led to the extinction of the dinosaurs.

This would have been a chunk of rock, at least 10 kilometers wide, falling from space at tens of thousands of miles per hour. A huge rock traveling really fast would create an immense amount of destruction when it hit the Earth.

Now, what are the immediate impacts? A rock traveling that fast through the Earth’s atmosphere would effectively create a void, a vacuum of space, following behind it. When it hits the Earth, it has this heat developed in front of it.

The heat of that impact would have created instantaneous fires across South America and southern parts of North America, with devastating effects. There would be extreme heat, the fires starting, and material covering the globe, potentially cutting light. The lack of light would kill off plant life, at least for a little while, and plants are the primary producers.

On any ecological scale, plants are the organisms that are feeding everything else. If the plants die, the plant eaters have no food, and they die. Then the meat eaters, the predators, no longer have a food source, and they die.

The crater from this impact was found in the Yucatan peninsula, off the Gulf of Mexico. The crater itself is covered by water and was relatively hard to see until scientists in the 1970s thought to explore it further. They went in and tested it, and sure enough, it was confirmed to be a big crater. The timing of the impact that formed this crater was also right around the time of the extinction of dinosaurs.

Blue Sky Science is a collaboration of the Wisconsin State Journal and the Morgridge Institute for Research.

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