An international team of researchers is claiming to have discovered traces of cholesterol on a fossil of Dickinsonia—a mysterious creature that lived during the primordial Ediacaran Period. This evidence, the researchers say, makes Dickinsonia the oldest known animal in the fossil record. But the discovery is not without its critics, who say the new work is unconvincing.
Is it or is it not an animal?
New research published [September 20] in Science suggests Dickinsoniawas a true animal, and not a fungus, plant, or protozoa (single-celled organisms) as previously suggested. The evidence used to support this claim is nothing short of extraordinary: cholesterol molecules found within a 558-million-year old Dickinsonia fossil from near the White Sea in northwest Russia. The researchers, led by Ilya Bobrovskiy from the Australian National University, believe the cholesterol, a type of fat, was produced by the individual when it was alive, and because cholesterol can only be produced by animals, Dickinsonia is thus deserving of the animal designation.
Other organisms, such as choanoflagellates and filastereans (simple, amoeba-like organisms), were unlikely to produce the biomarkers seen in the fossil, the researchers say.
“Our results make these iconic members of the Ediacara biota the oldest confirmed macroscopic animals in the rock record.” [said researchers.]
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