When and Where did Dinosaurs Live?
So we know that dinosaurs lived in the Mesozoic Era, but how long ago was that exactly?
This web site gives you a look at just how far back that was hereistoday.com
When you get to the current aeon, you will notice three eras: Paleozoic, Mesozoic, and Cenozoic. Dinosaurs existed only in the Mesozoic era, we are at the very end of the Cenozoic period.
Have a go at the Geologic Time Scale Activity (PDF) to get a better understanding of just how long ago the dinosaurs lived!
Ok, so dinosaurs lived a really long time ago, but WHERE did they live? Well, to answer that, we need to talk about something called plate tectonics (remember that we learnt about back in Planet Earth week). The centre of the Earth is mostly molten, liquid rocks that the crust floats on. The crust is the land we walk on, the bottom of the oceans, and goes down anywhere from 5-70 km (depending on where you are on Earth). The crust isn’t just one solid plate, though. It’s made of lots of separate plates that are constantly moving – which is why we get earthquakes and some volcanoes. This means that millions of years ago, Earth looked A LOT different than it does now.
At the beginning of the Triassic Period – the beginning of the Mesozoic era – all of the landmasses were connected in a supercontinent called Pangaea. This means that there were dinosaurs all over what we now call the seven continents. It was very dry in the centre of the continent with monsoon-like weather around the coastlines during this time. There were also no ice caps at this point.
At the beginning of the Jurassic Period, Pangaea was split into two continents called Gondwana and Laurasia. These continents also began to split by the mid-Jurassic into many of the continents we recognize today. In between these continents, the seas began to flood in, creating a more humid, subtropical climate. This time is known as the Golden Age of Dinosaurs – a time when dinosaur species began to diversify, or change a lot, because they were separated by the oceans.
Read more about a theory that dinosaur farts may have led to climate change at www.smithsonianmag.com.
Finally, in the Cretaceous Period, the continents drifted still further, closer to what we now recognize today. The sea level changed a lot during this time, with temperatures spiking in the middle of the period and then falling towards the end. During this time, different kinds of dinosaurs became common in specific locations – giant sauropods in the south, and at the end of the period, T-Rexes and other giant meat eaters dominated in the north. There were also various mammals, reptiles, birds, and fish which can be compared to modern day descendants. The Cretaceous Period, unfortunately, was the last time the dinosaurs would rule the Earth, though. On Friday, we will talk about some of the ways scientists think dinosaurs went extinct at the end of the Cretaceous Period.
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