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The Permian Mass Extinction: 250 Million Years Ago
Today, our world teems with life. Wherever you look, you see something that’s alive; whether it be a tree, a bird or just some guy walking down the street. Then try imagining 95% of all the life that you see disappearing in virtually one go. It sounds like some nightmarish fantasy, but way back in the depths of prehistory, something like this did happen. It occurred so long ago, that the time scale seems totally unfathomable to us. The dinosaurs became extinct 65 million years ago; well, this cataclysmic event took place roughly 190 million years before that, so you get an idea of just how far back it happened. It was a time known as the Permian, roughly 30 million years before the first giant dinosaurs would appear. The dominant creatures at the time were odd looking animals that can be best described as half mammal and half reptile, indeed they were known as mammal like reptiles, and they were first vertebrates to fully conquer the Earth’s surface. Among them were Scutosaurus, a strange looking beast with a bulky body covered with bony lumps, in its day it was the equivalent of cattle. It may have lived in small herds roaming the Permian flood plains. Perhaps the most terrifying creature living at the time was a predator called Gorgonops, an imposing creature about as big as a rhino, but with a sleek, wolf like body. It also possessed two formidable weapons that some mammalian predators would later evolve, sabre teeth. They were capable of leaping onto the backs of creatures like Scutosaurus and pierce their thick skin using their dagger like teeth. These creatures had ruled the Earth for some 30 million years, but events totally beyond their control would prove to be their undoing.
A Map of the World 250 Million Years Ago
The Great Dying
The creatures described above, lived a full 250 million years before the present, they were seemingly in their prime, but they and almost everything else on Earth would die in an apocalyptic extinction event, called the Permian Mass Extinction. It was the biggest reverse on what had seemingly been a forward march in evolution. Yet, surprisingly until recently, almost nothing at all was known about it. Scientists knew that there had been a mass extinction, but were totally baffled as to what had caused it, why it had happened or even whether such a terrible thing could ever happen again. For years it seemed as if this mystery killer had left no trace whatsoever, no footprints, no fingerprints, nothing.
Then in the early 1990s, scientists stumbled upon on something in the frozen wastes of Siberia. Buried deep beneath the permafrost are thousands upon thousands of miles of lava, it’s an area known as the Siberian Traps, and in the present era it’s covered in thick layers of snow, vegetation and permafrost. But, 250 million years ago, this area witnessed one of the biggest volcanic eruptions in the Earth’s history. As a consequence, hundreds of thousands of square miles of Siberia caught fire. That particular eruption is what is known as a Flood Basalt eruption, where the Earth’s crust splits apart and releases great streams of lava that can cover an entire continent and last millions of years. The numerous eruptions would have also sent vast clouds of dust and sulphur into the atmosphere, causing nuclear winters that lasted for decades.
But that was just the beginning; as the skies cleared; vast amounts of gas, given off by the burning lava would have gradually wrapped the whole planet in a blanket of carbon dioxide, thus causing a greenhouse effect and ultimately global warming, which made our present climate change crisis seem minuscule. The resulting cloud of gas was enough to warm the entire planet by five degrees celsius. As a consequence, the seas also heated, causing marine life to die on a biblical scale, including the famous trilobites- an order of aquatic arthropods that looked similar to woodlice, but were only distantly related. Prior to the mass extinction a wide variety of trilobite species coming in all shapes and sizes had roamed the oceans for over 300 million years. Then, something else happened; the super heated water was enough to cause the release of a great plume of methane gas from the ocean depths. Earth suffered another injection of greenhouse gas, pushing global temperatures up by a further five degrees to an astonishing ten degrees hotter than they had been before. If such a thing were to occur today, then arid deserts would spread as far north as England and the Canadian Border. The superheated planet wiped out virtually everything in the space of around 80,000 years. The initial temperature increase caused a mass extinction on land, then when the seas heated marine life perished, finally with the Earth ten degrees hotter, the final hammer blow fell on most of what was left on land.
The Siberian Traps Eruption
Lystrosaurus- The Ancestor of all Mammals
The greatest mass extinction event in Earth’s history would see evolution effectively reset itself. It took life around 100,000 years to recover, and when it did, a new family of reptiles would ultimately seize their chance and came to rule the world for the next 170 million years, the dinosaurs.
However, scientists have found fossilised remains of a strange looking mammal like reptile from the Permian world that managed to survive. It was approximately the same size as a cow, a herbivore and called Lystrosaurus. This creature has largely escaped our collective curiosity in regards to prehistory; instead our minds are full of Tyrannosaurus or enormous fifty tonne long necked giants. But this unobtrusive creature is probably one of the most important creatures that ever walked the Earth, because Lystrosaurus is probably the ancestor of all mammals, including us. We owe our very existence to a bizarre looking herbivore that somehow clung to life in the greatest mass extinction ever known.
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© 2012 James Kenny