A geologist has discovered rocks in Canada that may contain sponge fossils dating back 890— potentially making them the earliest fossil record of animal life on Earth
WASHINGTON — A Canadian geologist may havethe earliest fossil record of animal life on Earth, according to a report published Wednesday in the journal Nature.
Geologist Elizabeth Turner discovered the rocks in a remote region of the Northwest Territories accessible only by helicopter, where she has been excavating since the 1980s. Thin sections of rock contain three-dimensional structures that resemble modern sponge skeletons.
“I believe these are ancient sponges — only this type of organism has this type of network of organic filaments,” said Joachim Reitner, a geobiologist, and expert in sponges at the Germany’s University of Gottingen. The latter was not involved in the research.
The dating of adjacent rockyears old, making them about 350 million years older than the oldest undisputed sponge fossils previously found.
“What’s most stunning is the timing,” said Paco Cardenas, an expert on sponges at Sweden’s Uppsala University, who was not involved in the research. “To have discovered sponge fossils fromago will greatly improve our understanding of early animal evolution.”
Many scientists believe the first animal groups included soft
To be sure, there’s very little scientific consensus or certainty about anything datingago, so other researchers will likely continue to vet and debate Turner’s findings.
“I think she’s got a pretty strong case. I think this is very worthy of publishing — it puts the evidence out there for others to consider,” said David Bottjer, a paleobiologist at the. The latter was not involved in the research.
Scientists believe life on3.7 billion years ago. The earliest animals appeared much later, but exactly when is still debated.
Until now, the oldest undisputed fossil sponges date to around 540 million years ago, an era called the Cambrian period.
But scientists using a line of reasoning called the molecular clock — where they analyze the rate of genetic mutations to backdate when two species likely diverged —points to sponges emerging much earlier, around a billion years ago. Yet, no supporting physical evidence has been found until now.
“that a sponge fossil has been found from before the Cambrian, and not only before, but way before — that’s what’s most exciting,” said Uppsala University’s Cardenas, adding that the research seems to confirm the molecular clock estimates.
Fossil evidence is scant before the Cambrian period when animals first developed hard skeletons, exoskeletons, and shells, which are more likely to be preserved.
“Those kinds of fossils belong to more complicated animals — there has to be a back history” of simpler animals like sponges emerging first, said the paper’s author, Turner, based at Laurentian University in Ontario.
The dating of 890 million years ago is significant because, if the sponge’s identification is confirmed, it shows that the first animals evolved beforea level scientists once thought was necessary for animal life. Yet recent research shows that some sponges can survive with very little oxygen.
“Everything on Earth has an ancestor. It’s always been predicted that the first evidence of animal life would be small and cryptic, a very subtle clue,” said Roger Summons, an MIT geobiologist who was not involved in the research.
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