Until now scientists thought it was a lichen. Or maybe a giant amoeba. But the curious creature of the image, 558 million years old, had a guarded surprise: because it is indeed an animal. One that goes ahead in several million years to the oldest known until now and that is destined to revolutionize our knowledge about the origin of complex life.
It’s called Dicksonia, and in an article recently published in Science , an international team of researchers finally settled the long debate about the nature of the strange creature and described the finding as “the Holy Grail of paleontology.”
It all started when Ilya Bobrovskiy of the National University of Australia discovered an exceptionally well-preserved Dicksonian fossil near the White Sea in northwest Russia. The species dates back to the dark period called Ediacara , some 20 million years before the “Cambrian explosion”, the magical moment when Nature seemed to go crazy and all the animal genera that have thrived up to the present appeared.
But the new analysis shows that also some complex animals, and not only plants, fungi, and bacteria, were already firmly established long before the Cambrian, and Dicksonia was one of them. It is not, also, a small animal. The specimen discovered by Bobrovskiy and his colleagues measures almost one and a half meters , and its flat appearance is due to the process of fossilization. In fact, it presented an oval aspect in life, with a large number of fine ridges radiating on each side of a clearly visible central line.
A species known for 75 years
The species has been known for more than 75 years, and most of the discovered specimens, quite poorly preserved, come from the fossil deposits of the hills of Ediacara, in Australia, the place that gave its name to the entire period
But Bobrovskiy located his copy in a completely different place: in the middle of a cliff 100 meters high above the White Sea . And the fossil was so well preserved that it still contained fat molecules. The researchers managed to isolate and study these molecules, and conclusively identified them as cholesterol, a type of fat that only animals possess.
Therefore, the unexpected finding is destined to rewrite a good part of what we knew or thought we knew, about the history of life. In the words of Jochen Brocks, co-author of the study, “the fossil fat molecules we have found show that animals were large and abundant 558 million years ago, millions of years earlier than previously thought. That fossil fat has confirmed Dickinsonia as the oldest known animal and has solved a mystery that is decades old and that was considered as the Holy Grail of paleontology ».