Approximately 66 million years ago, near the conclusion of the Cretaceous Period, dinosaurs were extinct after a 175-million-year existence on Earth. The fossil record demonstrates that dinosaurs evolved into a wide diversity of forms over the first 175 million years of their existence as the environment changed and new species adapted to the new surroundings. Dinosaurs that did not adapt died out.
Except for birds, dinosaurs vanished altogether 66 million years ago in a relatively short period of time. Pterosaurs, enormous marine reptiles, and ammonites were among the other species that perished. Scientists are still debating the exact nature of this cataclysmic event.
Asteroid collision appears to have been the primary cause. Volcanic eruptions that resulted in large-scale climate change, as well as more gradual temperature shifts over millions of years, could have played a role. Whatever the causes, the massive extinction that terminated the dinosaur era left ecological voids all throughout the earth. The only dinosaurs that survived, birds, and mammals, stepped in to fill the void, and both evolved quickly. Learn more about the causes of the dinosaur extinction.
1: The dinosaur era was brought to an end by an asteroid.
There is evidence that an asteroid collided with Earth. On the edge of the Yucatan peninsula, near the Gulf of Mexico, a crater over 9 miles wide formed. Initially controversial, the Alvarez hypothesis is now the most widely accepted explanation for the mass extinction at the end of the Mesozoic Era.
The Chicxulub crater is located in the centre of the Yucatán Peninsula in Mexico. It is believed that the width of the asteroid was between 10 and 15 kilometres, but the crash left a 150-kilometer-wide crater because to its high speed. The collision that wiped out the dinosaurs hurled enormous volumes of debris into the air and produced enormous tidal waves to engulf portions of the American continents.
Approximately 75 percent of Earth’s creatures, including dinosaurs, perished at the same time. The asteroids impact was so powerful that it effectively vaporised it. It created a massive crater, therefore the surrounding land was completely devastated. A massive blast wave and heatwave erupted, propelling immense quantities of debris into the skies. It did not entirely obscure the Sun, but it did reduce the amount of light reaching the Earth’s surface. Thus, it affected plant growth.
This cascaded up the food chain like dominoes, forcing the ecology to collapse. The decline in plant life had a significant influence on the ability of herbivores to live, which in turn meant that predators had less food to eat. There would have been shorter breeding seasons and tougher conditions. All living things, both on land and in the ocean, would have been affected in some way. It was an enormous catastrophe that affected all life on Earth, from bacteria to dinosaurs. Ammonites, certain microscopic plankton, and big marine reptiles perished.
2: Eruptions of volcanoes
There was considerable volcanic activity starting around 70 million years ago, five million years before the K/T Extinction. Many volcanic eruptions occurred throughout the Cretaceous period, resulting in a rise in atmospheric carbon dioxide.
The high levels of carbon dioxide created a greenhouse effect, in which the heat energy that enters the atmosphere cannot be reflected back into the environment. As a result, the temperature rose and the ice caps began to melt. The melted ice from the arctic region raised the sea level, resulting in a deluge that killed all of the earth’s species.
An increase in carbon dioxide levels would have retained solar energy and prevented it from dissipating in space, leading in a rise in temperature. This increase in temperature would have killed or significantly diminished plankton activity, as well as their ability to convert carbon dioxide to oxygen through photosynthesis. It would not have taken long for the dinosaurs to suffer and eventually become extinct as a result of this. Suffocation caused by high levels of carbon dioxide in the atmosphere also killed the dinosaur embryo.
The idea also claims that the ocean became stagnant due to high levels of carbon dioxide in the atmosphere. Because there was no oxygen remaining for any species living in the ocean to breathe, there would be no food accessible.
3: The greenhouse effect
There was a lot of volcanic activity during the Cretaceous period. Volcanoes emit a large amount of carbon dioxide, and a large eruption has a high risk of triggering the greenhouse effect. According to scientists and palaeontologists, there were so many volcanoes throughout this last prehistoric period that they disfigured the Earth.
When they dug up dinosaurs from the Triassic and Jurassic periods, the bones were covered in dirt, soil, a little clay, and other common ground materials. When they discovered cretaceous dinosaur remains, however, there was usually special evidence of adjacent volcanoes. It could have been a unique common mineral produced by volcanoes, high sodium levels, or volcanic rock.
4: Massive flooding
Another hypothesis that is highly supported by evidence is that the Dinosaurs were wiped out by massive flooding. The fact that most of the dinosaur graveyards were formed by massive amounts of water supports the hypothesis that mass dinosaur extinction was triggered by massive floods.
The Dinosaur National Monument fossil quarry is one of the world’s greatest fossil deposits. There are 1,500 preserved dinosaurs in this quarry. The monument elaborates the reason for such a massive fossilised graveyard.
A mural painting depicting numerous dinosaurs wading through the river and the words “after a seasonal flood” may be found in the monument opposite the rock face. This is unequivocal proof that dinosaur corpses were transported by murky water and washed up on a sandbar. Some of it was buried fully in the sand and kept in a near-perfect form.
The 2007 collapse exposed a vast bed of dinosaur fossils in Lo Heuco, Spain, containing almost 8500 fossils of plants, invertebrates, and vertebrates, including an estimated 100 Titanosauruses and other dinosaur species. A palaeontologist at Cuenca’s museum later explained that such significant fossilisation was caused by frequent flooding.
5: All dinosaurs are extinct due to the ozone layer.
The ozone layer acts as a shield against these harmful radiation from ultraviolet rays. It protects the majority of the sun’s damaging energy from reaching the earth’s surface. The ozone layer in the atmosphere is about 10-25 miles thick and visible to the naked eye.
The ozone layer can be harmed by pollutants, and scientists frequently claim that automobiles and large industries are causing ozone layer degradation. Of all, there were no vehicles throughout the Triassic, Jurassic, and Cretaceous periods, so ozone levels should have been ideal when these massive animals roamed the world. Actually, there is one natural event that has the potential to seriously harm the ozone layer: volcanoes.
Dinosaur researchers have discovered that when they dig up Cretaceous dinosaur fossils, they also come across a lot of volcano rock in the same location. This is quite common, but only during the Cretaceous. Knowing this, dinosaur experts could infer that there were several volcanic eruptions at the time. When a volcano erupts, it spews not just millions of gallons of boiling lava, but also a large amount of a chemical known as hydrochloric acid. This hazardous gas has the potential to deplete the ozone layer.
One volcano may cause significant damage, but scientists know that throughout the Cretaceous period, volcanoes all over the world engaged in violent behaviour. Most Dinosaurs lacked fur, and many were notable for not always being in the water like crocodiles. This is demonstrated by the shape of their bodies. So we know they ran around on land, and if the ozone layer disintegrates, cancer will be free to spread throughout the globe. This would be the start of dinosaur extinction.