Mysterious Fossils in 3D

Emily Hughes brings us tales of adventure and discovery from the Australian Outback as she and her mother search for unbelievably ancient fossils. Her team digs up the creatures that form the evolutionary boundary between microorganism and animal—the Ediacaran biota. 

This field season in the Australian Outback, amidst rain, storms and the occasional scary wedgetail eagle attack (no kidding!), we did some really intriguing work on uncovering fossils preserved in three dimensions within rocks. Many of these fossils are new species and genera but others have been described before. The coolest of these fossils (in my opinion) is called Pteridinium, a fossil that previously had never been found in rocks this old, and one that still holds a lot of mysteries for our team to solve.

This Pteridinium was preserved on two sides of the rock, showing two of the three leaves. (Photo by Emily Hughes)

Pteridinium wasn’t originally discovered in the Australian Outback. Actually, they were first uncovered in Namibia in younger rocks than the 560-million-year-old ones that we work on. This is why it’s so exciting to have found them at the station where we work, as it gives a better sense of how long they were around, which is about 10-million years longer than previously thought. It also shows the different environments that they lived in, and that they had a global distribution, as they are now found on two different continents. There is currently a lot of controversy on what they looked like when they were alive.

The reason these fossils are preserved in three dimensions is because at some point, while they were on the seafloor, there was a bit of an underwater storm that caused them to become jumbled up within a pile of sand and muck, which we then found 560-million years later. We are still working on why they are actually preserved like this since they had no hard parts (so imagine some animal without a skeleton being preserved as a 3D mold within a sandstone—crazy stuff!). We think that they have been transported and mixed around, so it’s a little difficult to tell how they actually looked.

What we know is that Pteridiniums had three large blades. Some people believe that they met up in the center, converging into a point. Another popular idea is that the leaves formed a sort of triangle, and then came together at the top. If you need an idea of what this would have looked like, look up Pteridinium on the internet, and you’ll see recreations of both morphologies.

This year, since we’ve uncovered so many 3D Pteridiniums (I found one too!), we’re hoping to figure out their true morphology, size distribution, and even how they managed to stay attached to the seafloor. Were they under the sand? On top of it? Maybe we will even be able to figure out if they have living relatives.

Another Pteridinium, well preserved in the ancient rock.
Another Pteridinium, well-preserved in the ancient rock. (Photo by Emily Hughes)

The whole thing is rather exciting. It’s really fantastic to think that these rocks might hold the key to testing theories about these ancient creatures. It’s also rather incredible to think that the story of the Pteridinium is still only just beginning.

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Meet the Author
Emily Hughes is an undergraduate student at Wesleyan University, born and bred in Riverside, California. She has spent the majority of her summers exploring the Australian Outback, and finding, recording, analyzing and generally admiring the 560-million year old Ediacara fossils preserved there. She is a prospective double major in English and Earth and Environmental Science, and she works for the student newspaper as well as the sustainability office.