Virginia Tech researchers unraveled new evidence that suggests the earliest known mass extinction event on Earth was caused by a drop in oxygen levels about 550 million years ago.
This marks the sixth, and oldest recognized mass extinction event on the planet.
About 80% of the life on earth disappeared at the height of the Ediacaran period, according to the study and LiveScience.com, when the earth was filled with slug-like organisms and ancestors of jellyfish.
A study conducted by researchers at Virginia Tech suggests the missing fossils of these lifeforms signify the event.
“Previous work, by ourselves and others, had shown changes in diversity in these oldest animal communities, known collectively as the Ediacaran Biota,” Scott Evans, a postdoctoral researcher at Virginia Tech said on Thursday. “In order to quantify those changes in diversity and test hypothesized causes for such change, we compiled a database of every record of Ediacaran fossil occurrences from around the world.”
Evans said the study took about a year to conduct and consisted mostly of a literature review.
But that literature, he said, was built on decades of previous work to help understand the early animals.
Up to this study, scientists had accepted five mass extinctions on the record.
The Ordovician-Silurian extinction was 440 million years ago; Devonian extinction was 365 million years ago; Permian-Triassic extinction was 250 million years ago; Triassic-Jurassic extinction was 210 million years ago; and the Cretaceous-tertiary extinction was 65 million years ago.
This discovery places it 110 million years before the earliest known extinction.
Of the 20% of life that survived, scientists found they all had high surface area, which helps animals survive.
“I think the most important takeaway is that we now have a record stretching back 550 million years, demonstrating that animals respond to changing environmental conditions, often resulting in major extinction events,” Evans said. “Even though the causes of today’s environmental change and responses of animals may be different, the fact that such change in the past has been shown over and over again to lead to major extinction events is a crucial one when considering what actions we should take to mitigate the course of our current human driven climate change.”