1989 June National Geographic Magazine Blog

Hi! Today I will be doing a summary about a featured article in the 1989 June National Geographic magazine. Let's begin.

EXTINCTION: More than 99% of all species are extinct. Many of them died in one of the great five extinctions.

Here are the five great extinctions.

• Ordovician-silurian Extinction: 440 million years ago.
• Devonian Extinction: 365 million years ago.
• Permian-triassic Extinction: 250 million years ago.
• Triassic-jurassic Extinction: 210 million years ago.
• Cretaceous-tertiary Extinction: 65 Million Years Ago.
• (Quoted from https://www.amnh.org/)

The first extinction was during the end of the Ordivician. The ancient supercontinent moved closer and closer to the South Pole xausing colder water. Early fish survived but But most of the other invertabrates.

Then at the end of the Devonian most fish died in an extinction. 

During the third and the greatest extinction 95% of all Permian species died. This was most likely caused by super explosive volcanoes.

However dinosaur ancestors survived.

Then at the end if the Triassic most reptiles died but dinosaurs survived. This helped the dinosaurs to take over the world.

https://www.discovermagazine.com/planet-earth/how-the-triassic-extinction-helped-dinosaurs-take-over-the-planet

The dinosaurs survived for 165 million years.

But before we move on I want to tell you about a rarely mentioned small extinction.

https://www.sciencedirect.com/topics/earth-and-planetary-sciences/jurassic-cretaceous-boundary

The small extinction is about the Jurassic extinction. The link above will teach you about the Jurassic extinction. This especially was targeting stegosaurs which died out during the early Cretaceous.

The final great extinction killed 70% of the Cretaceous species including dinosaurs, mosasaurs, pterosaurs and ammonoids.

Then the Ice Age cam and ended in an extinction.

However, the Ice Age and Jurassic extinction were not great extinctions and were rarely mentioned.

Some scientists thought that we were in the middle of an extinction.

Are we?

Maybe we are.

Credit: National Geographic