There is much debate about what caused the mass extinction of dinosaurs, but their disappearance remains a mystery. Some scientists believe that an asteroid was responsible for this event; others say it might have been volcanic activity. Others who believe in global warming theory think the melting of polar ice caps caused an increase in temperature.
The mass extinction of dinosaurs occurred approximately 65 million years ago at the end of the Cretaceous/Tertiary (K/T) boundary. The extinction of the dinosaurs marked the end of the Mesozoic Era and the beginning of the Cenozoic Era. Paleoclimatologists have been trying to figure out why they died ever since. Here is a summary of the different theories.
Paleoclimatology: Global Anoxia – Lack of Oxygen
Palaeoclimatology is the study of ancient climates. It is a branch of geology that studies the Earth’s climate and atmospheric history. Ancient climates played a huge role in the mass extinction of dinosaurs on Earth. Studying Earth’s history is essential because it can help us understand the planet we live on today. The climate has a direct impact on our environment.
The dinosaurs were already starting to die out before the meteor hit. It sent a massive cloud of dust into the atmosphere that blocked out sunlight for years. The sunlight is crucial for photosynthesis. Plants died out, which meant herbivores had less food. The shortage of food meant that the dinosaurs couldn’t eat as much. It kept them alive but caused them to starve; they did not survive. This chain reaction continued through all levels of the food chain until pretty much everything was gone except for bacteria and fungi that could live off dead matter (like dung). The results of this chain reaction were devastating.
What about in the oceans? There are two parts to that story. Some scientists believe that there was more CO2 in the oceans thousands of years ago. If there were too much CO2 in the atmosphere, it would be hard for animals like plankton to breathe. And then there’s also evidence from some fossilized shells showing signs of acidification. It can kill off coral reefs and other vital habitats for marine life.
Methane Hydrates: When the Ice Melts, and the Methane Escapes
Methane hydrates are reservoirs of gas trapped in the ocean floor sediments or frozen ground. Ice crystals grow as the water gets colder and colder, and bubbles form inside them. These bubbles contain trapped methane molecules, called clathrates.
This phenomenon is best observed when the temperature is below zero degrees Celsius. Methane hydrates are only found in cold climates like Siberia or Antarctica. When temperatures rise above zero, these hydrates start melting. They release methane into the atmosphere, which causes global warming. This cycle can lead to an explosion of methane from under the ocean floor. It could have been what caused the mass extinction of dinosaurs.
Methane is very sensitive to changes in temperature and pressure. They can be so dangerous if they leak into our atmosphere or oceans. The release of methane hydrates into the atmosphere during the Cretaceous period could have accelerated global warming.
These temperatures would cause considerable changes in ocean currents and weather patterns worldwide. In some places, droughts have been severe, while flooding has been extreme in other places.
Acid rain is a problem that has been around for a long time. It’s caused by the same thing that causes global warming: carbon dioxide emissions. These emissions can be from factories, cars, and other sources of pollution. When these chemicals mix with water vapor in the air and then come in contact with sunlight, they form nitric acid—which falls to earth as acid rain.
And what does this have to do with dinosaurs? It turns out that acid rain might have played a role in killing almost all the dinosaurs.
The major factor leading up to this mass extinction event:
- a huge volcanic eruption in what is now known as India;
- Carbon dioxide flooded the atmosphere when acid rain nearly wiped out life on earth during the Permian period.
These factors caused global warming, an increase in CO2 levels that led to higher temperatures, leading to more releases of CO2 into the atmosphere… which led to more global warming… you see where this is going?
Acid rain occurs when gaseous pollutants, such as sulfur dioxide and nitrogen oxides, interact with water vapor in the atmosphere. This reaction creates acidic compounds that fall to earth as rain or snow.
The problem is that dinosaurs have very sensitive skin, which acids would easily damage. Also, acid rain can kill plants and animals that are not adapted to it – like many species of dinosaurs.
Dinosaurs were already in decline before the mass extinction event. Scientists believe that acid rain may have been one reason they could not recover from this decline and survive today.
This theory suggests that volcanic ash from Mt. Toba’s supervolcano eruption caused a nuclear winter-like effect on Earth. It led to the mass extinction of dinosaurs and many other species around 65 million years ago.
Volcanic winter is around 2 million years where volcanic eruptions spewed out so much carbon dioxide into the atmosphere that it caused a global cooling event. This effect would lead to heavy rains after large amounts of dust and aerosols entered Earth’s atmosphere.
It blocks the sunlight and causes temperatures to drop dramatically across all landmasses. This cooling event may have been responsible for the extinction of dinosaurs at the end of the Cretaceous period.
Deccan Traps Volcano Eruption
The most recent major extinction event occurred around 66 million years ago, caused by a massive volcanic eruption. The Deccan Traps eruptions were so large they covered an area of land the size of the United States and Russia combined. These eruptions were so powerful that they were directly linked to the extinction of non-avian dinosaurs (birds). What exactly happened?
It all started with a volcano in India. The Deccan Traps erupted for over 2 million years, spewing lava over 1,000 square miles. This lava was so thick that it turned into tuff rock. Unlike other types of sedimentary rock, these rocks didn’t disintegrate when exposed to water, wind, and erosion. Instead, they remained intact for millions of years until we could find them today.
Why did this eruption lead to the extinction of dinosaurs? When volcanoes erupt as this one did, it produces so much ash that it blocks sunlight from reaching Earth’s surface. Without sunlight, plants can’t grow—and eventually, living organisms will die.
The Asteroid Hypothesis: It Started with a Bang (Sort of)
The asteroid hypothesis is one of several theories about how dinosaurs became extinct. The theory posits that a large asteroid struck the Earth and caused the mass extinction that killed the dinosaurs. Even though this might seem like an easy explanation, scientists don’t know what caused the event and how life on Earth recovered.
One of the biggest questions that remains unanswered by this theory is what kind of effect such an impact would have had on our planet. Would it have been devastating enough to cause such widespread damage? Could it have even caused volcanic eruptions or other geological disasters? Many questions surround whether this was one single asteroid or more than one.
Another problem with this theory is that there are no actual physical remains from an impact site anywhere. Due to the nature of this period, we don’t know what happened or when it happened because there are no physical remains left behind for us to study millions of years after the event. Humans weren’t even around yet.
Ice Age at the End of the Cretaceous Period
An ongoing debate in paleontology is whether a climate change at the end of the Cretaceous period killed off the dinosaurs or if the dinosaurs were unable to adapt. One theory that has gained some traction recently is that a sudden increase in global temperature at the end of the Cretaceous period caused an ice age that wiped out many species of dinosaurs.
The other question is: where would all this water come from? The argument goes like this: There must be enough water on Earth to form glaciers for an ice age to occur. The water would have come from melting polar ice caps and rain falling over large land areas frozen.
Some scientists argue that it came from asteroids striking the Earth. Large asteroids may have carried enough water to cause an extinction event on a global scale. Others believe that volcanoes released so much CO2 into the atmosphere that it caused temperatures to rise enough for glaciers to form around the globe.
But what if there was another explanation for this mass extinction event? What if another natural phenomenon could explain what happened at the end of the Cretaceous period?
Fossils can explain the idea of a shallow sea in place of the Rocky Mountains from Mexico and Montana. Scientists hypothesized that this sea must have frozen over at some point in Earth’s history, causing many dinosaurs to die off as they couldn’t find enough food or water to survive.
Other scientists argue that this theory doesn’t hold up when looking at dinosaur fossils worldwide, including India and South America. They believe that dinosaurs thrived in warm climates and would have had no problem adapting to a changing climate—especially if humans hadn’t come along and driven them out of their habitats with hunting.
How Did Humans Affect the Mass Extinction of Dinosaurs on Earth Millions of Years Ago?
A common misconception is that humans caused the mass extinction of dinosaurs millions of years ago. In contrast, humans have indeed caused other species to go extinct in the past. At the time of dinosaurs’ extinction, humans did not exist. The first human ancestors had not yet evolved, so humans could not have caused the extinction of dinosaurs.
Some people still argue that humans were partly responsible for the extinction of dinosaurs. One example is hunting. This theory argues that human hunters killed too many large animals (like mammoths). It led to a dramatic change in climate and the environment on Earth that caused dinosaurs to go extinct. Scientists do not agree with this argument for several reasons:
- There were no humans during the era when most dinosaur species went extinct. It is unlikely that early man hunted these creatures for their fur.
- It’s unlikely that dinosaur species died out because of climate changes. They disappeared long before human hunters arrived on the scene.
The K-PG Extinction Event: The Culmination of Many Different Events Over a Long Period
The Cretaceous–Paleogene (K-PG) extinction event that wiped out the dinosaurs was not one event. It was the culmination of many different events over a long period.
It’s tempting to look at the fossil record and assume that there were some clear, simple causes for these extinctions — but it wasn’t that simple. Dinosaurs didn’t just die all at once; they died over thousands of years due to many factors.
Consider no dinosaur bones in the sediments above the K-PG boundary layer, and this means that they weren’t killed by an asteroid impact or something similar. They seem to have slowly disappeared over thousands of years. It leads us to believe that there must have been a long period of climate change leading to their eventual extinction.
The climate change debate has invariably centered around fossil fuels and stopping their use. Ancient history tells us that climate changes brought on by catastrophic events have been the norm throughout Earth’s existence. We have to accept that climate change was a natural part of Earth’s past and will continue to be for a long time to come.
The debate over whether the dinosaurs went extinct due to climate change is unlikely to be conclusively settled. The documented evidence for this phenomenon is sparse, so making a firm claim is difficult.