Scientists have found a “lost world” in a billion-year-old Australian rock

The “Lost World” of ancient organisms has been discovered by scientists in rocks billions of years old in northern Australia. According to the researchers, their findings could change the world’s understanding of the earliest human ancestors.

The microscopic creatures known as the protosterol biota are part of a family of organisms called eukaryotes and lived in the Earth’s waterways about 1.6 billion years ago, the researchers say.

As Al Jazeera explains, eukaryotes have a complex cellular structure that includes mitochondria, the “power center” of the cell, and the nucleus, its “control and information center.”

Modern forms of eukaryotes include fungi, plants, animals, and single-celled organisms such as amoeba.

Humans and all other germ-forming creatures can trace their ancestry back to the last eukaryotic common ancestor (LECA) who lived over 1.2 billion years ago.

The new discoveries “seem to be the oldest remnants of our own lineage – they predated LECA,” says Benjamin Nettersheim, who did his PhD at the Australian National University (ANU) and is currently based at the University of Bremen in Germany.

“These ancient creatures were abundant in marine ecosystems around the world and likely shaped ecosystems for most of Earth’s history,” the scientist continues.

The discovery of the protosterol biota is the culmination of 10 years of work by researchers at the Australian National University and was published in the journal Nature on Thursday.

Jochen Brox of ANU, who made the discovery with Nettersheim, said that the protosterol biota was more complex than bacteria and presumably larger, although it is not known what they looked like.

“We believe that they may have been the first predators on Earth, hunting and devouring bacteria,” the professor said in a statement.

Researchers from Australia, France, Germany and the United States examined fossil fat molecules found inside rock that formed on the ocean floor near what is now northern Australia.

Northern Australia is known for containing some of the best-preserved sedimentary rocks from the Earth’s Middle Ages (mid-Proterozoic period), including the oldest biomarker-bearing rocks on Earth.

“The molecular fossils found in these ancient deposits provide a unique insight into early life and ecology,” Nettersheim said.

The researchers found that the molecules had a primordial chemical structure that hinted at the existence of early complex creatures that evolved before LECA and have since become extinct.

“Without these molecules, we would never have known about the existence of the protosterol biota. The early oceans were mostly a bacterial world, but our new discovery shows that this probably wasn’t the case,” Nettersheim said.

Brox said that these creatures probably flourished from about 1.6 billion years ago to about 800 million years ago.

The end of this period in the Earth’s evolutionary timeline is known as the Thonian Transformation, when more advanced organisms such as fungi and algae began to flourish. But it is not known exactly when the protosterol biota became extinct.

“The Tonian transformation is one of the most profound ecological turning points in our planet’s history,” Brox says. “Just as the dinosaurs had to die out so that our mammalian ancestors could become large and abundant, perhaps the protosterol biota should have disappeared a billion years earlier to make way for modern eukaryotes.”