When Mesosaurus was alive, it was possible to walk between almost any two points on any two continents. Take the example of Mesosaurus , a creature not dissimilar from today's crocodiles. It was a freshwater reptile with a long, powerful jaw, which lived between and million years. Here is the weird part.
Facts About Pangaea, Ancient Supercontinent
Fossils of Mesosaurus are found, not just in South America, but Africa as well. It was a freshwater animal and could never have swum across the Atlantic Ocean to develop colonies on both continents. How did its fossils end up on either side of that vast ocean, then? The answer is simple: million years ago, there was no Atlantic.
Those two continents were joined, and Mesosaurus never had to swim that distance. In fact, when Mesosaurus was alive it was possible to walk between almost any two points on any two continents.
All the landmasses were united in the supercontinent Pangaea — which is something Scotese expects to happen again about million years from now when his "Pangaea Proxima" supercontinent forms. The existence of the ancient Pangaea is recorded in the distribution of other fossils.
Lystrosaurus , for example, was a giant herbivore. Its fossil remains are now found in Africa, India and even Antarctica. Even the plant Glossopteris , a woody shrub that grew to 98ft 30m in height, helps to confirm the idea that at one stage all of today's continents were jammed together as Pangaea. Importantly, the seeds of the plant were massive and could not have floated or been blown on the wind to other land masses. A supercontinent, on which the seeds could be dispersed via land, is thought to be the only credible explanation.
Amazing animation reveals how much Earth's continents have shifted over 540 million years
However, all these forms of evidence have their limitations. Beyond million years ago, the ancient magnetic record becomes much more patchy, so it is difficult to find hard evidence of continental movements. And at million years, says Scotese, the fossil record also becomes less detailed. As for predicting what will happen in the future, Scotese does this first of all by looking at how the plates are moving today and then extrapolating that movement over time.
This is the simplest way to develop a prediction. But, he adds, after many millions of years, there is no telling what geological events might cause unforeseen changes to that movement. Plate tectonics give us valleys and huge mountain ranges, earthquakes and continental boundaries. Various statistical models help to provide a range of options for how the continents will be arranged more than million years from now. But that is so far in the future, it is not clear to anyone how accurate these are. Still, it is fun to speculate, and it helps reinforce the reality that the Earth is an active, dynamic planet — the very face of which keeps changing.
And there are still mysteries about how they work.
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Hough points out that we are still investigating exactly why the Tibetan plateau, which lies north of the Himalayas, is as high as it is. Plus, our knowledge of plate tectonics on other planets is incredibly limited. Indeed, we have only recently found some evidence that suggests tectonics on Mars and Jupiter's moon, Europa. For now we can only wonder.
But plate tectonics have undoubtedly been significant for the development and dispersal of life on Earth. The secrets of the shifting ground beneath our feet have largely been revealed — and mostly within the last 50 years.
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For a long time we thought there was little more stationary and stable than the Earth beneath us. But now we know that Wegener, in principle, was right.
How Earth's continents became twisted and contorted over millions of years
The continents really did move — and they have not stopped yet. If you liked this story, sign up for the weekly bbc.
Earth Menu. Share on Facebook. Share on Twitter. Cancer Incidence in Five Continents, Vol. XI electronic version. Lyon: International Agency for Research on Cancer. Home Publications CI5. Fifty years after the plate tectonic revolution, we are pretty sure the continental parts of plates are not uniform, nor are they rigid. The giant forces that slowly move continents across the viscous mantle layer underneath, like biscuits gliding over a warm toffee ocean, stress the continents, and twist and contort the crust.
This is a process that has taken place over millions of years. As part of recent research, we worked with a team of international collaborators to build a computer model to show just how much the continents have been deformed since the Triassic Period, about million years ago. The supercontinent Pangea began breaking apart soon after, ripping along the seams between Africa and North America. We detail this new understanding of continent mangling in a paper published this month in the journal Tectonics.
Read more: Plate tectonics: new findings fill out the year-old theory that explains Earth's landmasses. We already knew that that colossal tectonic forces act along plate boundaries. We can see this when continents collide, such as when Africa collided with Eurasia, forming mountains like the Alps, or forming basins when continents are torn apart, as is happening in East Africa.
Our new research used geological and geophysical data to pinpoint all major zones of continental deformation, built into a global model of plate motions using our GPlates software. We show that at least one third of all continental crust has been massively deformed since Pangea first started breaking up. Read more: Curious Kids: how do mountains form?
When crust is being thinned and stretched, the crustal contortions are usually hidden away from view because they are quickly covered up by sediments. But there are exceptions. The East African Rift valley is one of the most spectacular examples of crustal extension visible at the surface.