March 28, 2023

Earth might be experiencing 7th mass extinction, not 6th – UC Riverside

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.

Diorama depicting Ediacaran-era sea creatures. (Smithsonioan Institution)


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

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

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

The researchers believe environmental changes are in order 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 will time, and the few species that did survive had bodies adapted with regard to lower o2 environments, ” said Chenyi Tu, UCR paleoecologist plus study co-author.  

Dickinsonia, a creature resembling the bath mat from the particular Ediacaran time period. (dottedhippo/iStock/Getty)

Unlike later events, this earliest one was more difficult to document because the creatures that will perished were soft bodied and did not preserve well in the fossil record.  

“We suspected such an occasion, but in order to prove it we had to assemble a massive database of evidence, ” said Rachel Surprenant, UCR paleoecologist and study co-author. The particular team documented nearly every known Ediacaran animal’s environment, body size, diet, ability to move, and habits.

With this particular project, the particular researchers sought to disprove the charge that the major loss of animal life from the finish of the Ediacaran period was something other than an extinction. Some previously believed the particular event could be explained by the right data not being collected, or a change in animal behavior, like the arrival associated with predators.

“We can see the particular animals’ spatial distribution over time, so we know they didn’t just move elsewhere or get eaten — they died out, ” stated Chenyi. “We’ve shown a true decrease within the abundance of organisms. ”

They also tracked creatures’ surface area to volume ratios, the measurement that suggests declining oxygen levels were to blame regarding the deaths. “If an organism has a higher ratio, it can get more nutrients, and the body from the animals that did live into the next era had been adapted in this way, ” mentioned UCR paleoecologist Heather McCandless, study co-author.

This project came from a graduate class led by UCR paleoecologist Mary Droser and her former graduate student, now with Virginia Tech, Scott Evans. For the following class, the students will investigate the particular origin of these animals, rather than their annihilation.  

Ediacaran creatures would be considered strange by today’s standards. Many of the animals could move, but they were unlike anything now living. Among them were Obamus coronatus , a disc-shaped creature named for the previous president, plus Attenborites janeae , a tiny ovoid resembling the raisin called for English naturalist Sir David Attenborough.

“These animals were the very first evolutionary experiment on Planet, but they only lasted about 10 mil years. Not long at all, in evolutionary terms, ” Droser said.  

Though it’s not clear why oxygen levels declined so precipitously on the end of the era, it is clear that will environmental change can destabilize and destroy life on Earth at any time. Such changes have driven all mass extinctions including the particular one currently occurring.  

“There’s a strong correlation between the success of organisms and, to quote Carl Sagan, our ‘pale blue dot, ’” stated Phillip Boan, UC Riverside geologist plus study co-author.

“Nothing is usually immune in order to extinction. We can see the impact of climate change on ecosystems and should note the devastating effects as we plan intended for the future, ” Boan mentioned.  

(Cover image: dottedhippo/iStock/Getty)

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