Welcome to brain Stuff from How Stuff Works, Hey, brain Stuff, Lauren Vogel bomb Here on the northern coast of the Yucatan Peninsula, near the town of Chichi Lob, Mexico, is a crater about a hundred and twenty miles in diameter. That's about a hundreds The asteroid that created this crater was about six miles that's ten kilometers wide and hit the Earth sixty five million years ago. In spite of these immense measurements, the crater is hard to see, even
if you're standing right on its rim. To get a good map, NASA researchers examined it from space. Ten years before the discovery of the Chichi Lob crater, physicist Louise Alvarez and geologist Walter Alvarez, a father son team, proposed a theory about the impact that we know today created it. They noted increased concentrations of the element a ridium in sixty five million year old clay. A Ridium is rare on Earth, but it's more common in some objects from space,
like meteors and asteroids. According to the Alvarez theory, a massive asteroid it had hit the Earth, blanketing the world in a ridium. But a shower of particles wasn't the only effect of the collision. The impact caused fires, climate change, and widespread extinctions. At the same time, dinosaurs, which until then had managed to survive for a hundred and eighty
million years, died out. Geo Physicist Doug Robertson of the University of Colorado at Boulder theorizes the impact heated Earth's atmosphere dramatically, causing most big dinosaurs to die within hours. This mass extinction definitely happened. Fossil evidence shows that about seventy of species living on Earth at that time became extinct. The massive die off marks the border between the Cretaceous and Tertiary periods of Earth's history, which are also known
as the Age of Reptiles and the Age of Mammals, respectively. Today, scientists call the extinction the KT event, after the German spellings of Cretaceous and Tertiary. The KT event had an enormous effect on life on Earth. But what would have happened if the asteroid had missed. Would it have led to a world where people and dine sours would coexist
or one in which neither could live? In a world where an asteroid whizzed past Earth instead of crashing down with the force of a hundred million tons of TNT, life could have progressed much differently sixty five million years ago. Some of the animals and plants that are common today we're just getting started. These include placental mammals, which are mammals that develop inside a placenta in the womb, and angiosperms, which are flowering plants. Insects that rely on flowers, such
as bees, were also relatively new. Many of these life forms thrived after the KT event, and without that mass reptilian extinction to clear the way, they may not have found ecological niches to fill. In this scenario, today's world might be full of reptiles and short on mammals, including people. But even if the asteroid hadn't hit, dinosaurs and other Cretaceous life forms might have become extinct anyway. Some dinosaur species had started to dwindle long before the asteroids impact.
This has led many researchers to conclude that the asteroid was just one spect of a complex story. Other global catastrophes like massive volcanic eruptions in what is now India most likely played a role. Also, the Earth's changing landscape as the supercontinent Pangaea broke up into today's continence probably had something to do with it too. Then, there's another argument that the Chicktullub asteroid hit the Earth too early
to have caused the extinction. Researchers GERTA. Keller and Marcus Harding both conclude that the impact took place three thousand years before the end of the Cretaceous period. Keller theorizes the Chicktullub impact was one of at least three massive collisions. Harding argues that the iridium layer didn't come from the Chichillub asteroid, but from another event, such as a series of meteors burning up in the atmosphere. He bases this
theory on spheroid particles ejected during the impact. Most of these are in an older layer of the Earth than the Katie irridium layer. According to both of these points of view, the absence of the chick Tallub asteroid strike may not have had a big effect on the Hayti extinction. Earth was a warm planet for most of the time that dinosaurs lived. After the end of the Cretaceous period, the world got a lot colder and experienced several ice ages.
Whether dinosaurs could have survived such a change in climate is debatable. It's hard to come to a definitive conclusion about what the world would look like today without the Chick to Love impact, but the question of whether people and dinosaurs could have coexisted is a captivating one. The idea is present in everything from the congo legend of mokol Ambenbe to King Kong to the pervading kitch of
the Flintstones. Then, of course, there's the prevailing scientific theory about the origin of birds that they are, in essence, dinosaurs that we are coexisting with today. Today's episode was written by Tracy V. Wilson and produced by Tyler Klang. Brain Stuff is a production of I Heart Radio as How Stuff Works. To hear more from Tracy, check out the podcast Stuff You Missed in History Class, and for more on this and lots of other historic topics, visit
our home planet how Stuff Works dot com. And for more podcasts from my heart Radio, visit the I heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.