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(LEICESTER, UK) — Paleontologists are marveling over the unique fossil of a marine species that predated the dinosaurs, according to new research.
The fossil, dated to about 444 million years ago, contained a new species of arthropod that fossilized inside-out, according to a paper published in the journal Palaeontology last week.
The discovery was described by researchers as a “legless, headless wonder,” according to a statement from the University of Leicester.
The “exceptionally preserved” euarthropod was found with its muscles, sinews, tendons and guts all preserved in “unimaginable detail,” said Sarah Gabbott, a professor at the University of Leicester’s school of geology and lead author of the paper, said in the statement.
“Remarkably her insides are a mineralised time-capsule,” Gabbott said, adding that the specimen’s head and legs were lost to decay over hundreds of millions of years.
The new species was dubbed “Keurbos susanae,” or “Sue” — after the mother of the woman who discovered it. Researchers are certain it is a primitive marine arthropod, but the precise evolutionary relationships remain “frustratingly elusive,” Gabbott said.
The fossil was located on Soom Shale, a band of silts and clays about 250 miles north of Cape Town, South Africa. At the time the strata was laid down, a “devastating” glaciation had wiped out about 85% of Earth’s species — one of the “big five” mass extinctions in Earth’s history, the researchers said.
But the marine basin where Sue was found was somehow protected from the worst of the freezing conditions and provided shelter for a community of “fascinating” species, according to the paper.
“This fossil is just so beautifully preserved there’s so much anatomy there that needs interpreting,” Gabbott said. “Layer upon on layer of exquisite detail and complexity.”
The sediments that trapped the specimen were extremely toxic, the researchers said. The water contained no oxygen, but hydrogen sulphide — described as not only “stinky” but deadly — was dissolved in the water, the researchers said.
An unusual chemical alchemy may have been responsible for the unique way Sue was fossilized, the researchers hypothesized.
About 85% of the animals on Earth today are arthropods — including shrimps, lobsters, spiders, mites, millipedes and centipedes, the paper stated.
The downside to Sue’s unique fossilization is it makes it hard to compare the specimen with other fossils of similar species of the time.
“So it remains a mystery how she fits into the evolutionary tree of life,” according to the researchers.
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