1. Summary

Over 65 million years ago, most types of dinosaurs went extinct after roaming the earth for 160 million years. Some scientists believe an asteroid approximately 12km wide had hit the Earth causing the extinctions. Other scientists predict that massive volcanoes irrupted long before the asteroid which resulted in dinosaur extinctions.

2. Why Watch This Video?

• Have you ever wondered how much damage the asteroid caused that may have caused dinosaurs to go extinct?
• Would you like to know how soot impacted the survival of dinosaurs?
• Have you ever been confused as to why some species survived the mass extinction?

3. Key Terms

• Chicxulub crater – A 150 km wide impact crater buried underneath the Yucatan peninsula in Mexico.
• Soot – A smoky, black powder like substance that occurs after the incomplete burning of organic matter.
• Asteroid – A rock located in space that orbits the sun and is greater than 10 m across. It travels at almost 11km/s.

4. Loose Ends

Dinosaurs aren’t actually extinct.

Although it’s common to say that the dinosaurs went extinct, that’s not entirely true. Yes, the organisms we most readily think of as dinosaurs did become extinct, but birds are in fact actual living dinosaurs. Sometimes this distinction is made by saying that the non-avian (non-bird) dinosaurs went extinct.

Which other species survived?

In the video it explains many species survived the extinction, but it does not go in detail of which ones survived. A variety of other species also survived on land, including frogs, snakes, lizards and mammals. It is believed the smaller you were, the higher your chances of survival were. Crocodiles, on the other hand, survived because of hibernation. They are smaller than dinosaurs which also helped with their diet to eat less. Birds are the only dinosaurs to survive the mass extinction event that happened 65million years ago. Birds had larger brains which allowed them to better adapt when the environment changed after the mass extinction. Lizards are distant relatives of dinosaurs that survived the extinction. Mammals came to dominate the land. all primates, including humans, survived the extinction. Although, a number of snake species died out around 65 million years ago, snakes as a group survived. Of the known species of turtles alive, at the time of the dinosaurs, more than 80 percent survived. The turtles survived because of their slow metabolism and aquatic lifestyles. All these species survived because of their diet, and their great adaptability.

How fast did the dinosaurs really die?

In the video they make it look like dinosaurs went extinct as soon as the asteroid hit the Earth. However, in reality, non-avian dinosaurs died off a couple thousand years after the impact of the asteroid. The video is rushed and makes the timeline of the extinction short.

Why were the effects global rather than just where the asteroid hit?

The video describes when the asteroid hit the earth, the temperature and climate change. It would get really hot at some points and really cold in others. Based on the amount of soot in the global debris layer, the entire terrestrial biosphere might have burned, implying a global soot-cloud blocking out the sun and creating an impact winter effect. The collision would have released the same energy as more than a billion times the energy of the atomic bombings of Hiroshima and Nagasaki. So that explains why it got really hot and wildfires spread all over the world. The sea surface temperature dropped as much as 7 °C for decades after the impact causing marine life to die off.

5. Self-Test Questions