Scientists analyzed ancient fossils
Scientists have discovered fossils of some of the earliest known animals dating back 575 million years, the discovery shedding light on how our earliest animal ancestors functioned, according to the Australian National University (ANU). The team of ANU researchers studied fossils from the Ediacaran period recovered from Russia and discovered new clues about the physiology of our earliest animal ancestors.
Ediacara biota is the oldest large organism in the world and dates back to 575 million years. The ANU researchers found that the animals ate bacteria and algae from the ocean floor. The findings, published in Current Biology, reveal more about these strange creatures, including how they could consume and digest food, ANI reported.
The scientists analyzed ancient fossils that contained preserved phytosterol molecules, natural chemicals found in plants, that were left over from the animals’ last meal. By examining the molecular remains of what the animals ate, the researchers were able to confirm that the slug-like organism, known as Kimberella, had a mouth and gut and digested food in the same way that modern animals do. Researchers say it was probably one of the most advanced creatures of the Ediacarans.
The ANU team found that another animal, which grew to 1.4 meters long and had a rib-like design printed on its body, was less complex and had no eyes, mouth or gut. Instead, the strange creature, called Dickinsonia, absorbed food through its body as it traversed the ocean floor.
“Our findings suggest that the animals of the Ediacaran biota, which lived on Earth before the ‘Cambrian Explosion’ of modern animal life, were a mixed bag of outliers, such as Dickinsonia, and more advanced animals such as Kimberella which already had some physiological properties similar to humans and other animals today,” said lead author Dr. Ilya Bobrovskiy of GFZ-Potsdam in Germany.
Both Kimberella and Dickinsonia, which have a different structure and symmetry than those that exist today, are part of the Ediacaran family of biota that lived on Earth about 20 million years before the Cambrian explosion, a major event that forever changed the course of evolution. of all life on Earth.
“Ediacara biota are actually the oldest fossils large enough to be visible to the naked eye, and they are the origin of us and all animals that exist today. These creatures are our deepest visible roots,” Dr. Bobrovskiy, who completed the work as a part. from his PhD at the ANU, he said.
Study co-author Professor Jochen Brocks, from the ANU Research School of Earth Sciences, said the algae are rich in energy and nutrients and may have been instrumental in Kimberella’s growth.
“Energy-rich foods may explain why organisms in the Ediacara biota were so large. Almost all fossils that came before the Ediacara biota were single-celled and microscopic in size,” said Prof Brocks.
Using advanced chemical analysis techniques, ANU scientists were able to extract and analyze the sterol molecules contained in the fossil tissue. Cholesterol is the hallmark of animals and is how, in 2018, the ANU team was able to confirm that the Ediacaran biota is among our oldest known ancestors.
The molecules contained telltale signatures that helped researchers decipher what the animals ate before they died. Professor Brocks said the difficult part was differentiating the signatures of fat molecules from the same creatures, the remains of algae and bacteria in their guts and the molecules of decaying algae on the ocean floor that were all buried in the fossils.
“Scientists already knew that Kimberella left feeding marks by scraping the algae that covered the sea floor, suggesting that the animal had a gut. But only after analyzing the molecules in Kimberella’s gut were we able to determine what exactly he ate and how he fed. digested food,” Professor Brocks said.
“Kimberella knew exactly which sterols were good for it and had an advanced gut tuned to filter out everything else.
“This was a Eureka moment for us; by using a chemical preserved in fossils, we can now make the gut contents of animals visible even if the gut has long since deteriorated. We then used this same technique on stranger fossils like Dickinsonia to find out how it fed and discovered that Dickinsonia didn’t have a gut.”
Dr. Bobrovskiy recovered fossils of Kimberella and Dickinsonia from steep cliffs near the White Sea in Russia, a remote part of the world where bears and mosquitoes exist in 2018.
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