What Really Killed The Dinosaurs | BBC Earth

Summary

Dinosaurs once dominated Earth for 140 million years, but their sudden disappearance remains a mystery. Scientists investigated a rock layer called the KT boundary, which marks the time of their extinction. They discovered a high concentration of iridium, a rare element usually found in asteroids, suggesting a massive impact. This asteroid, about 10 km in diameter, could have created a fireball equivalent to 10 billion Hiroshima bombs, potentially causing widespread destruction and extinction. The theory points to an extraterrestrial cause for the dinosaurs' abrupt end.

Takeaways

• 😀 Dinosaurs were dominant on Earth for 140 million years without significant competition, except from other dinosaurs.
• 😀 Around 65 million years ago, dinosaurs suddenly disappeared, leading scientists to investigate the cause.
• 😀 Scientists discovered a mysterious layer of rock called the KT boundary, marking the sudden disappearance of dinosaurs.
• 😀 The KT boundary contains a high concentration of iridium, an element rarely found on Earth but common in space.
• 😀 The presence of iridium suggested an extraterrestrial impact, such as an asteroid or comet, contributed to the extinction event.
• 😀 The asteroid that likely caused the extinction was estimated to be around 10 kilometers in diameter.
• 😀 The impact of this massive asteroid would have generated a fireball equivalent to 10 billion Hiroshima bombs.
• 😀 The shockwave from the asteroid's impact would have devastated life over a vast area, possibly hundreds of miles.
• 😀 The discovery of iridium at the KT boundary helped scientists pinpoint the time of the mass extinction event.
• 😀 The KT boundary is a sharp, thin layer, indicating a catastrophic event that dramatically altered Earth's ecosystems.

Q & A

What was the dominance of dinosaurs like on Earth?

Dinosaurs were among the most successful animals to ever roam the planet, dominating Earth for approximately 140 million years without significant competition, except from other dinosaurs.

What event caused the extinction of dinosaurs?

The extinction of dinosaurs was likely caused by a catastrophic event, which scientists believe was an asteroid or comet impact, leading to dramatic environmental changes.

What is the KT boundary and why is it important?

The KT boundary is a thin layer of rock that separates two major geological periods: the time before and after the dinosaurs' extinction. It is significant because it marks the exact point in time when dinosaurs disappeared from Earth.

How do scientists know that the dinosaurs were wiped out by an impact?

Scientists discovered a high concentration of iridium in the KT boundary layer. Iridium is rare on Earth but common in asteroids and comets, suggesting that a massive impact occurred at the time of the dinosaurs' extinction.

What is the significance of the iridium found in the KT boundary?

The presence of iridium, which is found in unusually high amounts at the KT boundary, supports the theory that an asteroid or comet impact contributed to the extinction event. This element is typically associated with extraterrestrial objects.

How large was the asteroid that impacted Earth during the dinosaur extinction?

The asteroid believed to have caused the dinosaur extinction was estimated to be about 10 kilometers (6 miles) in diameter, which is large enough to have caused catastrophic global effects.

What would the impact of the asteroid have been like?

The impact would have released an enormous amount of energy, creating a fireball equivalent to 10 billion Hiroshima bombs. The resulting shockwave would have destroyed life across hundreds of miles.

What happened to the environment as a result of the impact?

The asteroid's impact likely caused massive fires, tsunamis, and atmospheric disturbances. These events would have drastically altered the climate and environment, leading to the extinction of many species, including the dinosaurs.

Why was the KT boundary layer so critical for understanding the extinction event?

The KT boundary provided a clear marker for when the extinction occurred, as it showed a sharp distinction in fossil records. Dinosaur fossils are found below this layer, while they are absent above it, indicating their sudden disappearance.

How long did dinosaurs dominate Earth before their extinction?

Dinosaurs dominated Earth for about 140 million years, from the Triassic period to the end of the Cretaceous period, making them the most successful group of animals on the planet during that time.