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A spongy structure discovered in 890-million-year-old rock unearthed in Canada’s Northwest Territories may be the oldest known fossilized animal body, according to a study that will add to the longstanding debate about the planet’s oldest animal life.
In An article published Wednesday in the journal NatureElizabeth Turner, a geologist at Laurentian University in Ontario, described the branching, tubular structures she observed when examining ultrathin slices—about as thick as a human hair—that were once reefs in a prehistoric ocean. Dr. Turner suggests that the web-like structures are very similar to the fiber webs of modern keratosis sponges, also known as horny sponges. to create worldwide today.
But he admits what he sees under the microscope may not be clear when animal life first appeared on Earth.
“Perhaps there is another explanation. My comment is not the final word,” said Dr. Turner. “It is possible that I could be wrong.”
Some believe it is. “It could just be microbial wiggles,” said Jonathan Antcliffe, an evolutionary biologist specializing in sponges at the University of Lausanne in Switzerland. The evidence supporting the claim that they are the remains of an ancient sponge is “very, very thin,” he said.
The putative fossils were excavated from the 890-million-year-old Little Dal reefs in northwestern Canada, which now expose parts of the Mackenzie Mountains. If confirmed, they would date the oldest undisputed sponge fossil to around 350 million years ago, which is longer than today and when dinosaurs first evolved.
“We’re talking about adding hundreds of millions of years without leaving a trace,” said Graham Budd, a paleobiologist at Uppsala University in Sweden. “It would be sensational. It would be like finding a computer chip in a 14th-century monastery.”
The research highlights the challenges of identifying and making sense of the oldest existing fossil record when scientists aren’t sure exactly what to look for and there isn’t much to look at. “If we expect the first animals to be small and soft, that’s the best we can expect,” said evolutionary biologist Maja Adamska of the Australian National University, who was not involved in the new paper.
There are other controversial claims regarding the timeline of the emergence of life on Earth. Discoveries of ancient, “spongy” fossils have been reported – and later controversial – In Namibia, Russia, Australia, China, Newfoundland and Ukraine. In the early 1990s, scientists at the University of California, Los Angeles claimed to have found the world’s oldest, bacteria-battered fossils. was later dismissed like oddly shaped minerals. In 2016, scientists suggested that the 3.7 billion-year-old conical structures found in Greenland stretch the fossil record back 200 million years; two years later, three-dimensional analysis refuted fossil claims.
“The further you go back in time, the harder it is to interpret,” said palaeontologist and geobiologist Gert Wörheide of Ludwig Maximilians University in Munich. “This is speculation and that’s okay.”
In the sponge evolution study, horny sponges they are notoriously difficult. They lack many of the animal’s most distinctive and fossil-friendly features, including mineralized skeletons and skeleton-like. spicule buildings. Accordingly, there is no scientific consensus on how to tell the earliest potential fossils, other than the geological traces of ancient organisms such as fungi or bacteria, or the geological traces of something else that has since gone extinct.
Dr. “It’s no coincidence that this claim is for an incredibly poorly understood group,” Antcliffe said. “This is an inkblot test. They found something and said, ‘It reminded me of a sponge’.”
In the article, Dr. Turner argues that undulating reef microstructures are too coherent and complex to be geological, and do not closely resemble the branching styles of other organisms such as fungi or algae.
He adds that the evolution of a life form does not necessarily begin with a fossil record (reaches back for sponges). 535 million year).
“They didn’t show up. Their evolution must have had a history, potentially a long one,” Dr. Turner said. “We didn’t look closely enough – that’s one reason for the difference.”
On Tuesday, Dr. Turner said he was prepared for the article to be met with criticism, given that the field is full of uncertainties. “I know this is going to be a feeding frenzy,” she said. “And it’s okay. Bring it.”
If his hypothesis turns out to be correct, the 890-million-year-old sponge fossils raise other difficult questions: How did sponges survive the ice ages, and how did they survive? dramatic rises in oxygen? How have they managed to escape fossilization or human gaze until now? And when did animal life really begin to flourish on Earth?
“We’re really far beyond what we can be sure of. This article shows you how little we know,” he said. To get definitive answers, he said, “We need a time machine.”
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