Earth is currently in the midst of a mass extinction, losing thousands of species every year. New research suggests that environmental changes caused the first such event in history, which occurred millions of years earlier than scientists thought.
Most of the dinosaurs disappeared 66 million years ago, at the end of the Cretaceous. Before that, most of Earth’s creatures became extinct between the Permian and Triassic periods, approximately 252 million years ago.
Thanks to the efforts of researchers at the University of California at Riverside and Virginia Tech University, a similar extinction is now known to have occurred 550 million years ago, during the Ediacaran (or Ediacaran) period. This discovery has been published in an article by Proceedings of the National Academy of Sciences.
Although it is not clear if this represents a true “mass extinction”, the percentage of organisms lost is similar to that of these other events, including the current one in progress. Researchers believe that environmental changes are responsible 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 survived had bodies adapted to environments with less oxygen.said Chenyi Tu, a paleoecologist at UCR and co-author of the study.
Unlike other later events, this first one was more difficult to document because the creatures that perished were soft-bodied and were not well preserved in the fossil record.
We suspected this was such an event, but to prove it we had to assemble a huge database of evidence.said Rachel Surprenant, a UCR paleoecologist and co-author of the study. The team documented the environment, body size, diet, mobility, and habits of nearly all known Ediacaran animals.
With this project, the researchers tried to refute the charge that the great loss of animal life at the end of the Ediacaran period was something other than extinction. Some previously believed that the event could be explained by inadequate data being collected, or by a change in the animals’ behaviour, such as the arrival of predators. We can see the spatial distribution of animals over time, so we know that they didn’t move to another place or were eaten, but rather became extinct.Chenji said. We have shown a true decline in the abundance of organisms.
They have also tracked the ratio of the creatures’ surface area to volume, a measurement that suggests declining oxygen levels were to blame for the deaths. If an organism has a higher ratio, it can get more nutrients, and the bodies of the animals that did live in the next era were adapted this way.said UCR paleoecologist Heather McCandless, a co-author of the study.
Ediacaran creatures would be considered weird by today’s standards. Many of the animals could move, but they were not like anything that now lives. Among them are obamus coronatusa disc-shaped creature named after the former president, and Attenborites janeaea tiny raisin-like ovoid named after the English naturalist Sir David Attenborough. These animals were the first evolutionary experiment on Earth, but they only lasted about 10 million years. Not a long time, in evolutionary termsDroser said.
Although it is not clear why oxygen levels fell so precipitously at the end of the era, it is clear that environmental change can destabilize and destroy life on Earth at any time. Such changes have fueled all mass extinctions, including the one currently occurring.
There is a strong correlation between the success of organisms and, to quote Carl Sagan, our ‘pale blue dot’said Phillip Boan, a UC Riverside geologist and co-author of the study. Nothing is immune to extinction. We can see the impact of climate change on ecosystems and should take note of the devastating effects when planning for the future..
Sources
University of California Riverside | Scott D. Evans, Chenyi Tu, Adriana Rizzo et al., Environmental drivers of the first major animal extinction across the Ediacaran White Sea-Nama transition. PNAS 119 (46) e2207475119, doi.org/10.1073/pnas.2207475119