The Day the Earth Nearly Died

250 million years ago, long before dinosaurs roamed the Earth, the land and oceans teemed with life. This was the Permian, a golden era of biodiversity that was about to come to a crashing end. Within just a few thousand years, 95% of the lifeforms on the planet would be wiped out, in the biggest mass extinction Earth has ever known. What natural disaster could kill on such a massive scale? It is only in recent years that evidence has begun to emerge from rocks in Antarctica, Siberia and Greenland.




The demise of the dinosaurs, 65 million years ago (at the so-called K/T boundary), was as nothing compared to the Permian mass extinction. The K/T event killed off 60% of life on Earth; the Permian event 95%. Geological data to explain the destruction have been hard to find, simply because the rocks are so old and therefore subject to all kinds of erosion processes. It seems plausible that some kind of catastrophic environmental change must have made life untenable across vast swathes of the planet.

In the early 1990s, the hunt for evidence headed for a region of Siberia known as the Traps. Today it's a sub-Arctic wilderness but 250 million years ago, over 200,000km² of it was a blazing torrent of lava. The Siberian Traps were experiencing a 'flood basalt eruption', the biggest volcanic effect on Earth. Instead of isolated volcanoes spewing out lava, the crust split and curtains of lava were released. And the Siberian flood eruption lasted for millions of years. Could volcanic activity over such a long time alter the climate enough to kill off 95% of life on Earth?

Monsters We Met

When our early ancestors entered new lands they encountered a variety of strange new creatures, monsters that no longer exist. What were they like and where are they now? What are the real answers to the mystery of the missing megafauna?




Some scientists believe there is damning evidence that humanity hunted the megafauna to extinction. The 'overkill' hypothesis holds that the megafauna vanished only a few centuries after the arrival of man and that hunting was the primary cause of the extinctions, for the following reasons:

• only the larger animals disappeared
• there is archaeological evidence of human hunting
• animals had survived previous times of climate change

There have been many mass extinctions throughout geological history, the most well-known being the disappearance of the dinosaurs at the end of the Cretaceous Period. In analysing these events, scientists find that small, medium and large species all become extinct, although large animals (those over 44kg adult weight) always suffer the heaviest loss. These large animals are termed 'megafauna'.

In contrast, the extinctions at the end of the Pleistocene seem to target large animals, with the small to medium ones escaping relatively lightly. Scientists that support the overkill hypothesis believe that this evidence points to humans as the culprits. The impact of human hunters on populations of large, slow-maturing, slow-breeding animals, such as mammoths and diprotodons, was bound to be far greater than any effect they might have had on small, rapidly breeding prey such as hares or squirrels. Therefore, the overkill theory seems to explain why only the megafauna died out.

PART ONE

PART TWO

Opponents of the overkill hypothesis point to a variety of evidence that human hunters were not the culprits. Their arguments against humanity as killers are:

• long periods of human-megafauna coexistence
• little evidence of hunting
• people were hunting the wrong species

For the overkill hypothesis to hold true, prehistoric humans must have killed off the megafauna very rapidly - within 1,000 years of arriving in a region. If the extinction happened more slowly than this, it wouldn't have been true overkill. More to the point, it may be impossible to pick apart all the interrelated factors (hunting, climate and competition) that would have played a part over a longer period.

The Dinosaur Fossil That Fooled The World

In February 1999 at a vast gem and mineral fair in the US desert city of Tucson, an amazing fossil from China came on to the market It was priced at $80,000 and only the very top dealers were invited to see it. It had the head and body of a bird and the tail of dinosaur. It had all the characteristics of one of the most sought-after fossils in all paleontology – the missing link that proved once and for all that dinosaurs evolved into birds.




One of the world’s most revered and widely-read magazines became involved. In exchange or an exclusive story, it agreed to fund the analysis if the fossil. A team of top experts in the field were assembled to examine the new discovery.

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In October 1999, a press conference was held at the magazine’s headquarters to publicise their international scoop. The magazine proclaimed a new species, archaeoraptor lianoningensis. Then, after a detective story that followed a path across China, the awful truth emerged.The fossil was a fake. It had been constructed out of fragments of several different animals. One of the world’s most respected popular science journals had made a terrible mistake.

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It's a palaeontologist's dream: the chance to live in a world where dinosaurs are not something to be dug out of the ground but are living among us. It may sound far-fetched but dinosaurs were actually rather unlucky. The meteorite impact that doomed them to extinction was an event with a probability of millions to one. What if the meteorite had missed?




Had dinosaurs survived, the world today would be very different. If humans managed to survive alongside them, we wouldn't have the company of most, if not all, of the mammals with which we are familiar today. Giraffes, elephants and other mammals wouldn't have had space to evolve.

Would we be hunting Hadrosaurs instead of elk? Or farming Protoceratops instead of pigs? Would dinosaurs be kept as pets? And could the brighter dinosaurs have evolved into something humanoid?