How dinosaurs became extinct (Explanation)

Just under 66 million years ago the Mesozoic Era ended in a mass extinction. It destroyed all the giant dinosaurs, the pterosaurs, most marine reptiles and many other animals that we now know only from fossils.

Scientists are still not certain whether the extinction was caused by the asteroid strike or by the devastating eruption of masses of lava and poisonous gases from the gigantic Super Volcanoes.

These are some of the theories that scientists have come up with:

Super Volcanos - Vast quantities of molten lava flooded over half of India and cooled to form layers of basalt rock 2km deep. The layered rocks are called the Deccan Traps.

Volcanic Cloud - Enormous clouds of gas shrouded the globe.

Acid Rain - Chemicals in the volcanic ash mixed with water to cause deadly acid rain.

Asteroid Impact - The explosion caused by the asteroid strike formed a crater over 180km wide, now buried deep underground. Debris from the impact would have filled the atmosphere. The explosion caused by the asteroid strike formed a crater over 180km wide. It is one of the biggest asteroid craters on earth, but it is invisible from the ground. The explosion would have sent a cloud of dust into the air that was thick enough to block out the sun which caused plants and animals to slowly die out

Explosion Debris - Dust mixed with a chemical haze would have blocked vital sunlight for at least a year.

Global Forest Fires - Searingly hot molten rock ejected from the impact would have triggered huge wildfires across the world.

Blast and Shock Waves - The shock of the cataclysm must have destroyed all life near the impact zone.

Mega Tsunami - There is evidence of huge tsunamis that swept across the Caribbean and Atlantic coasts

Climate Crisis - Whether it was colossal volcanoes, the impact of a massive asteroid, or a combination of the two, the effect was catastrophic climate change that chilled the Earth and wrecked the global ecosystem. The world took millions of years to recover.

While some types of animals disappeared, others somehow survived both the initial catastrophe and the years that followed, when plants struggled to grow and food was scarce. The first group of animals was the Sharks. Along with other fish, these survived in the oceans. They carried on evolving into the sleek hunters they are know. Next are Frogs. Freshwater animals seem to have been shielded from the worst effects, allowing frogs to survive into the new era.

The third is Turtles. Surprisingly, more than 80% of turtle species alive in the Cretaceous still existed after the extinction event. Next are Snakes. Many lizards and snakes made it through the crisis and became ancestors of all the lizards and snakes alive today. The fifth are Mammals. All the main group of mammals living at the time survived, eventually flourishing in the Cenozoic Era.

Next are Insects and Spiders. Small land invertebrates were badly hit but many groups escaped extinction and eventually started to flourish again.

The seventh are Shellfish. Many types of marine invertebrates such as the sea urchins survived. But others vanished, including the ammonites. The catastrophe also wiped out all the pterosaurs and most other marine reptiles. At least 75 percent of all animals and plant species were wiped out.

The final result is that dinosaurs have been extinct for millions and millions of years, and are unlikely to ever return.