Earth is currently in the midst of a mass extinction, losing thousands of species each year. New research suggests environmental changes caused the first such event in history, which occurred millions of years earlier than scientists previously realized.

Most dinosaurs famously disappeared 66 million years ago at the end of the Cretaceous period. Prior to that, a majority of Earth’s creatures were snuffed out between the Permian and Triassic periods, roughly 252 million years ago. 

Thanks to the efforts of researchers at UC Riverside and Virginia Tech, it’s now known that a similar extinction occurred 550 million years ago, during the Ediacaran period. This discovery is documented in a Proceedings of the National Academy of Sciences paper. 

Although unclear whether this represents a true “mass extinction,” the percentage of organisms lost is similar to these other events, including the current, ongoing one. 

The researchers believe environmental changes are to blame for the loss of approximately 80% of all Ediacaran creatures, which were the first complex, multicellular life forms on the planet. 

“Geological records show that the world’s oceans lost a lot of oxygen during that time, and the few species that did survive had bodies adapted for lower oxygen env