This year has been chock-full of asteroids closely passing by Earth. Dozens in fact. In late January, there was asteroid 2004 BL86, which was so large it even had its own moon. There was the $5 trillion asteroid 2011 UW158 composed of an estimated 90 million tons of platinum that hurled passed us in July. On October 31, astronomers were given a Halloween treat with the passing of asteroid 2015 TB145. And next, we have Santa to thank for asteroid 2003 SD220, which will whiz by us on Christmas Eve.

All these near misses got us thinking, what if that dinosaur-killing asteroid never smashed into Earth around 65 million years ago? Would the dinosaurs still be alive? Would human evolution still have been possible? Would dinosaurs and humans coexist?

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We posed this hypothetical question to paleontologist Jack Horner, a dinosaur expert best known for discovering the Maiasaura dinosaur nesting site, which contains the first dinosaur eggs and embryos found in the Western Hemisphere.

Michelle Nash isn't good at writing about herself. She runs web series for Fusion and hopes you enjoy the videos as much as she enjoyed making them. Follow her at @hello_michello.

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