They find the oldest known relative of living animals

More than 500 million years ago, the Earth’s oceans were occupied by strange creatures. Among them was the extraordinary Dickinsonia, which resembled a giant bath mat on the seabed, or plant-like beings that were actually animals anchored to the bottom of the ocean. But one of those fantasies might be a little more familiar, having undulating stalks and tentacles reminiscent of a jellyfish. Researchers at the University of Oxford have named this fossil Auroralumina attenboroughii in honor of the famous British naturalist and popularizer David Attenborough. It is between 556 and 562 million years old and may be the oldest example of an evolutionary group still living today.

Scientists place the origin of modern animals around 539 million years ago during the so-called Cambrian explosion. At that time, creatures with specialized tissues, organs, guts, and symmetrical left and right sides began to appear, all traits we recognize in animals today.

However, older fossil finds challenge that belief. As explained in the journal ‘Nature Ecology & Evolution’, the researchers discovered the new fossil in Charnwood Forest, a mountainous area of ​​Leicestershire, in central England. Using the radioactive decay of uranium into lead, they dated the rocks surrounding the fossil to be about 560 million years old.

symmetrical body

The 20-centimeter fossil is two-pronged with long stems topped by tentacled cups. The organism appears to be in its polyp stage, the life cycle in which it attaches itself to the ocean floor and uses its tentacles to catch larvae and floating plankton. The body has quadruple symmetry, meaning it is symmetrical at all four corners from a central point, as modern jellyfish are.

A cast of the new fossil

BGS UKRI

The team concluded that A. attenboroughi It is a cnidarian and a member of the subgroup called Medusozoa, which contains modern jellyfish. If true, “our fossil becomes the oldest animal with direct living descendants in the fossil record,” Frances Dunn, a paleobiologist at Oxford, tells Science.

In the same journal, Alexander Liu, a paleobiologist at the University of Cambridge who was not involved in the study, comments that it is “more like a modern animal group than anything else of that antiquity or earlier.”

As for the name of the creature, the researchers chose Aurora Lumina to reflect the ancient age of the fossil. In Latin, it would be something like ‘dawn light’. For its part, Attenboroughii it is a tribute to Attenborough, who spent his childhood near Charnwood and raised awareness of his fossils.

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