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What Caused the Dinosaurs to Go Extinct?

The demise of the dinosaurs, a mystery that has captivated scientists for ages, is widely attributed to a catastrophic asteroid impact 66 million years ago. This event triggered a global climate upheaval, rendering the Earth inhospitable for these ancient giants. But what if there's more to the story? Join us as we uncover the layers of this prehistoric puzzle.
Michael Anissimov
Michael Anissimov
Michael Anissimov
Michael Anissimov

All dinosaurs, except a few which would later go on to become modern birds, went extinct about 65.5 million years ago, during the Cretaceous-Tertiary extinction event. No land animal larger than a cat survived. The sky was largely blacked out for a period of years to decades, killing numerous plant and microbe species which rely on photosynthesis to survive. Species that depended on the consumption of plant matter, such as all vegetarian dinosaurs, went extinct when their food sources died off and decomposed. In North America alone, 57% of plant species went extinct. In paleontology, the layer of rock that corresponds to this extinction is known as the K-T boundary.

Even today, we don't know with 100% confidence what really caused this massive extinction. But the prevailing theory, by Nobel Prize-winning physicist Luis Alvarez, is that a 6-mile asteroid impacted the Earth, releasing the energy of 2 million atomic bombs and raining molten magma across the entire surface of the planet.

The asteroid that hit what is now Yucatan, Mexico had the power of 2 million atomic bombs.
The asteroid that hit what is now Yucatan, Mexico had the power of 2 million atomic bombs.

Alvarez's extinction theory is supported by two facts: first, the huge Chicxulub crater on the Yucatan peninsula in Mexico can be dated to the time of the K-T boundary. Second, all across the world, the K-T boundary rock contains an unusually high proportion of iridium, a substance very rare of the Earth's surface, but more plentiful in asteroids. This suggested that the debris from the impact fell everywhere on the globe. This illustrates the destructiveness of the impact. The rock underneath the crater is rich in gypsum, which would have produced clouds of sulfur dioxide aerosol in the aftermath of the collision, resulting in acid rain and killing marine creatures that depend on their shells for survival.

A large asteroid impact is believed by many to be the cause of dinosaur extinction.
A large asteroid impact is believed by many to be the cause of dinosaur extinction.

Being very large and exposed on the surface, as well as more highly dependent on smooth ecosystems than less specialized plants and microorganisms, dinosaurs were hit with the brunt of the extinction effects. The Chicxulub asteroid slammed into the Earth at an angle, traveling northwest. This would have thrown magma-hot, ballistically reentering ejecta all across what is today the central United States, an area known for its large dinosaur populations.

Speculation continues as to the exact cause of dinosaur extinction.
Speculation continues as to the exact cause of dinosaur extinction.

The direct effects of the heat could have killed off 99% or more of the dinosaurs within hours. Those who were able to survive the rain of magma would die over the next years or decades, their food sources drying up, and ecosystems becoming completely unraveled. Life would never be the same again: from that point on, it was not the dinosaurs, but smaller warm-blooded animals that would thrive on planet Earth.

Michael Anissimov
Michael Anissimov

Michael is a longtime AllTheScience contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

Michael Anissimov
Michael Anissimov

Michael is a longtime AllTheScience contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

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Discussion Comments

anon251257

It's a basic concept of 2012 by now. Back in 1990, this would be helpful but now in 2012, this is basic preschool common sense.

anon110847

This info is useful but i need help writing a report.

anon87481

i found this article particularly helpful due to the fact that i have a very important assignment based on the extinction of the dinosaur.

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    • The asteroid that hit what is now Yucatan, Mexico had the power of 2 million atomic bombs.
      By: The Official CTBTO Photostream
      The asteroid that hit what is now Yucatan, Mexico had the power of 2 million atomic bombs.
    • A large asteroid impact is believed by many to be the cause of dinosaur extinction.
      By: Mopic
      A large asteroid impact is believed by many to be the cause of dinosaur extinction.
    • Speculation continues as to the exact cause of dinosaur extinction.
      By: Kabacchi
      Speculation continues as to the exact cause of dinosaur extinction.