How did the Dinosaurs die?

On this page we’ll be discussing the scientific evidence which should help you answer the question – “how did the dinosaurs die?”

66 million years ago there was a big mass extinction episode which resulted in catastrophic results for dinosaurs. This extinction episode was not thought to be as big as the Permian – Triassic extinction event that made 90 – 95% of the World’s species extinct, but its impact was still devastating.

Three quarters of the world’s life ended, including many commonly recognized groups such as dinosaurs, plesiosaurs and mosasaurs, as well as many other lesser known groups. Leaving some birds, fish, mammals, and small reptiles to evolve and spread on earth. Forests were said to have burned out across much of the earth.

How did the dinosaurs die

The original uploader was Fredrik at English Wikipedia., Public domain, via Wikimedia Commons

two main EXTINCTION theories

This mass extinction was the second-most extensive in the history of the Earth. Years of volcanic eruptions produced massive waste landscapes and filled the atmosphere with poisonous gases and debris. Life on Earth began choking to death. Some of the areas on the Earth became full of geothermal springs and the air became thick with sulphurous fumes and carbon monoxide.

So let’s start by discussing some of the scientific evidence to help answer the question “How did the dinosaurs die?”

There are two main theories on how the dinosaurs died and why this mass extinction happened has been the basis of many scientists’ discussions over the years. The strongest theory was an asteroid impact which had an immediate devastating ripple effect, and the second theory was a large-scale climate change which was caused by volcanic eruptions. We will look at these in more depth now.

Volcanic eruptions

Some scientists still believe that the volcanic eruptions located were the main reasons why the dinosaur extinction happened. Scientists know that this volcanic range called the Deccan Traps, located in India, had lava spewing out around the same time that dinosaurs became extinct but don’t know exactly the dates of these eruptions. 

The Deccan Traps is a huge place and they are one of the largest volcanic features on earth. Back then it is believed it covered 1,500,000 sq km (600,000 sq miles), and even now the distance is 500,000 sq km (200,000 sq miles). It was from here that some scientists believe was the catalyst of why the dinosaurs became extinct.

Volcano eruption

C.G. Newhall, Public domain, via Wikimedia Commons

Scientists believe that the amount of lava and gases that came from these eruptions resulted in a global climate change and therefore life was significantly reduced. Lava would have killed everything for miles, while the gases would have travelled globally.

Asteroid impact

Scientist agree that the most plausible answer to the question “How did the dinosaurs die?”  was because of an Asteroid impact.

Dinosaurs were roaming the earth for around 165 million years before the asteroid collided with earth causing a catastrophic global impact.

If we compare this to humans, our earliest ancestors have been around for 6 million years, with the modern form of humans only 200,000 years. So dinosaurs had been on earth for 30 times longer which is difficult to comprehend. But don’t worry, NASA recently came out and said we are safe for at least 100 years having risk assessed any potential asteroid heading this way

Earth being bombarded by asteroids.

Image source: NASA

Luis & Walter Alvarez 

The theory of an asteroid impact was a result of research by a team of scientists being led by Luis Alvarez and his son Walter. Luis was an American multi award winning experimental physicist, inventor, and professor who won amongst other achievements the Nobel Prize in Physics. His son Walter, was also a multi award winning professor in Earth and Planetary Science. 

For most scientists this hypothesis would have been the highlight of their careers, but for Luis especially, this was just one thing that defined his career, he had already won the Nobel prize for previous work.

The team which included nuclear chemists, brought out a paper in 1980 that was underpinned by the research on neutron activation analysis which concluded that the dinosaur extinction was likely to have occurred by an asteroid collision with the earth. It was an immensely controversial paper which caused huge debate in the scientific world.

It was, and is known as the Cretaceous–Paleogene (K–Pg) extinction event. On the 4th of March in 2010 a panel of 41 scientists agreed that Luis & Walter’s theory was correct.

So what happened?

An asteroid first of all are small, rocky objects that orbit the sun, they are in effect “mini planets”. Any fragment that survives and lands on earth is known as a meteorite and in this case was named the Chicxulub impactor.

There was a large crater discovered in Mexico by a couple of geologists in 1970 but could not prove it was a crater and it was not until 2016 when a scientific deep drilling project took place to get rock samples 100’s of meters below current sea levels. These samples seemed to prove the theory and the crater is known as the Chicxulub crater and named after the nearby communities.

To give you some perspective of the size of the impact, the meteorite was estimated to be 11 – 81km (6.8 – 50.3 miles) in diameter and left a hole measuring 100km (62 miles) wide and 30km (19 miles) deep.

The crater is mainly under the sea and has since been covered by over 600m (2,000ft) of sediment. 

Chicxulub impactor

Image source: Nasa

The energy release when the Chicxulub impactor struck earth was at a scale of 100 million megatons (a lot of energy), the largest ever man made bomb was 50 megatons so it had 2,000 times the energy.

Scientists have said this impact would have caused a mega tsunami at over 100 meters (330ft) tall and would have been so powerful it would have reached Texas and Florida. In fact if the meteorite had hit earth in deep waters (instead of shallow waters) the tsunami waves may have had unimaginable heights of 1.5km (1 mile) and would have travelled to coastlines around the world. 

Winds would have been over 1000kph (621mph) near the blasts centre, and nearly all life within a 1,000km (621 miles) would have been wiped out and that was before taking into account the debris that would have travelled for miles.    

The Immediate after effects

The amount of force would have caused a huge earthquake at a scale of magnitude 12 at point of impact and 9 globally from the ripple effect. The highest recorded earthquake in modern times is 9.5 for comparison.

Volcanoes erupted, triggered by the shockwaves, along with emissions, and dust particles that could have covered the whole of the Earth’s surface for years after the event meant living conditions were extremely tough.

Volcano Eruption

R. Clucas, Public domain, via Wikimedia Commons

Carbon dioxide would have led to a sudden greenhouse effect and scientists have said sunlight could have been blocked out from the earth’s surface by dust particles for up to a decade after impact.

The earth’s temperature would have cooled considerably and plants died as they could not get the sunlight to photosynthesis which would have had a huge negative knock on effect to the food chain. Rain would have been acidic as it mixed with the carbon dioxide and dust particles reducing life even further and increased the acidity of the oceans.

The long term effects

The immediate loss of life due to impact was huge but the after effects in respect of reducing life would have been even more devastating, which scientists have said may have taken decades or even longer.  

Earth went through a period of climate change, for 2 million years it was possible volcanic activity was frequent in the now central India region. This rise in activity increased the acidity and made living conditions even harder.

Could the dinosaurs have survived?

Whether dinosaurs could have lived if the asteroid had not impacted is often debated. Also what if the asteroid had impacted on a different part of the planet?

These are all hypothetical questions that can be the basis of interesting research. Some scientists believe if the impact didn’t happen at all, climate change may have brought about an evolution and they would have died out eventually anyway, while others believe relations of the dinosaurs may still have been around today.

Herrerasaurus skeleton

Sharat Ganapati from Chicago, USA, CC BY 2.0, via Wikimedia Commons

So, was it an Asteroid or Volcanoes that killed the dinosaurs?

So, how did the dinosaurs die? Well, the research is compelling and leans heavily towards the asteroid theory, but who knows what scientists will discover in the future, as well as the advance in technology to help support theories.

Last Updated on 09/07/2021 by admin