A small black stone commemorating a student during a study trip to the Western Australian outback has been broken open to reveal the remains of the 2.4 billion-year-old creatures inside.
What is remarkable about these microfossils is that they appear to be more complex than anything known at the time. Not just in a few years, but in 750 million.
They appear to belong to the domain of complex life called eukaryotes—a domain that includes animals, plants, and fungi. It used to be thought that all that existed was single-celled, bacteria-like life called prokaryotes.
While the texture of the fossils is extremely good, the chemical information has been degraded and this makes it difficult to prove the hypothesis. But due to the serendipitous series of events that led to the discovery, scientists are determined to continue studying this mysterious find.
Related: An extremely rare merger of two life forms prompts an exciting evolutionary prediction
A chance event leads to the discovery of microfossils inside the rock
The layered limestone rock, known as black crumb, was found by geologist Dr. Erica Barlow in the Pilbara and took it home as a keepsake. As a student at the University of NSW, she was pursuing a different line of research before her supervisor, Professor Martin Van Kranendonk, noticed it on her desk.
“The particular type of rock that Erica had on her desk is well known to contain microfossil samples,” Van Kranendonk told Yahoo News. “I’ve seen some of these types of stones, but this particular specimen looked extraordinarily glassy.
Even though the pair were studying in a geology lab, the chances of anyone knowing about the significance of the black horn was low. Maybe a few dozen people around the world would recognize it.
The chance of discovering the rock was also slim. “It was literally a needle in a haystack,” Van Kranendonk said.
An ancient landscape where microfossils were discovered
To get to the remote Western Australian town of Pilbara where it was located, you have to travel a long and bumpy dirt road.
“It’s terribly hot in the summer. But it’s a beautiful wilderness – it’s still a very untouched part of the world in the southern Hamersley Ranges,” said Van Kranendonk.
“Along the course of the river are wide open valleys which are filled with rubber trees. And then these dark red ranges with all the iron. It’s spectacular.”
Why is the stone so important?
The period to which the rock was dated is significant because it saw the Great Oxidation Event—the tipping point that marks the rise of oxygen in Earth’s early atmosphere.
The event was theoretically related to a jump in the complexity of life, but physical evidence was lacking.
When the researchers looked at the fossils inside, they didn’t resemble anything they’d seen before. It is the first fossil of its kind known in the geological record.
Since the original discovery of the rock, Barlow has returned to the site and found the entire rock face littered with black hornblende for miles. A few small pieces were removed and taken back to the lab for further study.
Van Kranendonk hopes that as technology advances, it will be possible to create a definitive analysis of microfossils that will allow them to determine whether the creatures are inside a eukaryote.
During this research project, Van Kranendonk was a professor at the University of NSW. He is now the new Head of Earth and Planetary Sciences at Curtin University in the Faculty of Science and Engineering.
Do you love Australia’s weird and wonderful environment? Get ours new newsletter presents the best stories of the week.
