<p>If it had not occurred, humans and their ancestors may not have evolved, or could have evolved very differently, said researchers from the University of Chicago.<br /><br />According to them, key features shared by all modern mammals, birds and reptiles -- such as five-digit limbs -- originated when life re-emerged after the mass extinction, the Daily Mail reported<br /><br />"Everything was hit, the extinction was global," said lead researcher Lauren Sallan.<br />"It reset vertebrate diversity in every single environment, both freshwater and marine, and created a completely different world."<br /><br />The Devonian Period, which stretched from 416 to 359 million years ago, is also known as the Age of Fishes. A broad array of species filled the oceans, rivers and lakes, but most were unlike any alive today, the researchers said.<br /><br />Armoured placoderms, such as monstrous 30-foot carnivore Dunkeosteus, and lobe-finned fishes similar to modern lungfish dominated the waters, while ray-finned fishes, sharks and four-limbed tetrapods were in the minority.<br /><br />But the picture changed abruptly with the traumatic Hangenberg extinction.<br />"There's some sort of pinch at the end of the Devonian," said Prof Michael Coates, from the University of Chicago.<br /><br />"It's as if the roles persist, but the players change: the cast is transformed dramatically.<br />"Something happened that almost wiped the slate clean and, of the few stragglers that made it through, a handful then re-radiate spectacularly."<br /><br />According to the scientists, new fossil finds and analytical techniques brought to light the full impact of the Hangenberg event.<br /><br />However, what happened to trigger the mass extinction still remains an unsolved mystery. Many believe that substantial glacier formation at the end of the Devonian would have dramatically affected sea levels.</p>.<p>The first appearance of forest-like environments may also have produced atmospheric changes with catastrophic consequences for life.<br /><br />"It is a pivotal episode that shaped modern vertebrate biodiversity," said Professor Coates.<br /><br />"We are only now beginning to place that important event in the history of life and the history of the planet, which we weren't able to do before."<br /><br />The research is published in the journal Proceedings of the National Academy of Sciences. </p>
<p>If it had not occurred, humans and their ancestors may not have evolved, or could have evolved very differently, said researchers from the University of Chicago.<br /><br />According to them, key features shared by all modern mammals, birds and reptiles -- such as five-digit limbs -- originated when life re-emerged after the mass extinction, the Daily Mail reported<br /><br />"Everything was hit, the extinction was global," said lead researcher Lauren Sallan.<br />"It reset vertebrate diversity in every single environment, both freshwater and marine, and created a completely different world."<br /><br />The Devonian Period, which stretched from 416 to 359 million years ago, is also known as the Age of Fishes. A broad array of species filled the oceans, rivers and lakes, but most were unlike any alive today, the researchers said.<br /><br />Armoured placoderms, such as monstrous 30-foot carnivore Dunkeosteus, and lobe-finned fishes similar to modern lungfish dominated the waters, while ray-finned fishes, sharks and four-limbed tetrapods were in the minority.<br /><br />But the picture changed abruptly with the traumatic Hangenberg extinction.<br />"There's some sort of pinch at the end of the Devonian," said Prof Michael Coates, from the University of Chicago.<br /><br />"It's as if the roles persist, but the players change: the cast is transformed dramatically.<br />"Something happened that almost wiped the slate clean and, of the few stragglers that made it through, a handful then re-radiate spectacularly."<br /><br />According to the scientists, new fossil finds and analytical techniques brought to light the full impact of the Hangenberg event.<br /><br />However, what happened to trigger the mass extinction still remains an unsolved mystery. Many believe that substantial glacier formation at the end of the Devonian would have dramatically affected sea levels.</p>.<p>The first appearance of forest-like environments may also have produced atmospheric changes with catastrophic consequences for life.<br /><br />"It is a pivotal episode that shaped modern vertebrate biodiversity," said Professor Coates.<br /><br />"We are only now beginning to place that important event in the history of life and the history of the planet, which we weren't able to do before."<br /><br />The research is published in the journal Proceedings of the National Academy of Sciences. </p>