Newly discovered mass extinction in Earth’s past was likely caused by climate change

‘Nothing is immune to extinction. We can see the impact of climate change on ecosystems and should note the devastating effects as we plan for the future.’

RIVERSIDE, Calif. — Earth is losing thousands of new species each year for many reasons like deforestation, hunting, and climate change. Although scientists have thought that the planet’s current mass extinction event is the sixth in history, a new study has found a seventh!

This newly discovered event was also the result of environmental changes that led to a wave of extinctions. Researchers from the University of California-Riverside (UCR) suggest this first mass extinction occurred millions of years earlier than scientists theorized and was triggered by similar conditions Earth is facing now.

Dinosaurs died out around 66 million years ago at the end of the Cretaceous period. Before the meteor struck, however, most living beings on Earth were already dying out about 252 million years ago. The study suggests a similar extinction happened 550 million years ago in the Ediacaran period. What’s more, hazardous environmental conditions appeared responsible for the loss of almost 80 percent of Ediacaran creatures. Ediacaran beings are regarded as the first complex, multicellular lifeforms on Earth.

“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 environments,” says study co-author Chenyi Tu, a paleoecologist at UCR, in a university release.

There’s little evidence left from prehistoric times

The reason why it’s been difficult for paleontologists to pinpoint the first mass extinction in this time period is because there are not many well-preserved fossil records still around. Most creatures had soft bodies, which don’t hold up as well compared to bones and hard shells.

“We suspected such an event, but to prove it we had to assemble a massive database of evidence,” says co-author and paleoecologist Rachel Surprenant.

The study authors amassed a database of every known Ediacaran animal along with their habitat, body size, diet, ability to move, and habits. The goal was to search for alternative solutions beyond extinction that could explain why nearly all animals perished at the end of the Ediacaran period. Collecting every feature related to the animals could provide a possible explanation not seen before, such as the arrival of new predators or a disadvantageous change in animal behavior.

‘Nothing is immune to extinction’

One important finding was found in a creature’s surface area to volume ratios. This measurement suggests declining oxygen levels were at fault for animal death.

“If an organism has a higher ratio, it can get more nutrients, and the bodies of the animals that did live into the next era were adapted in this way,” comments Heather McCandless, a paleontologist at UCR and study co-author.

Animals in the Ediacaran family were anything but ordinary. While these animals moved around, the authors say they were unlike anything sees in a modern-day creatures. Some examples include the Obamus coronatus, named after the former president, which was a disc-shaped creature. The Attenborites janeae, was an egg-shaped animal that was the size of a raisin. These animals lasted about 10 million years, which according to researchers, is not a long time.

While we still don’t know what triggered the loss of oxygen towards the end of the Ediacaran period, study authors suggest the reason is likely environmental changes. Environmental changes can happen at any time, with some capable of destroying life and propelling mass extinctions.

“Nothing is immune to extinction. We can see the impact of climate change on ecosystems and should note the devastating effects as we plan for the future,” concludes UCR geologist Phillip Boan.

The study is published in the journal Proceedings of the National Academy of Science.