The Kimberella fossil. Credit: Ilya Bobrovskiy/GFZ-Potsdam
Key Points:
- Analysis of fossils has revealed the last meal consumed by earth’s earliest animals.
- Kimberella and Dickinsonia lived about 575 million years ago.
- The fossils were retrieved from steep cliffs near the White Sea in Russia.
A new study shed light on the contents of the last meal consumed by the earliest animals known to inhabit Earth more than 550 million years ago.
“Ediacara biota really are the oldest fossils large enough to be visible with your naked eyes, and they are the origin of us and all animals that exist today,” said first author Ilya Bobrovskiy, who completed the work as part of his PhD at AustralianNational University. “These creatures are our deepest visible roots.”
For the study, published in Current Biology, scientists analyzed ancient fossils containing preserved phytosterol molecules—natural chemical products found in plants—that remained from the animals’ last meal. The molecules contained tell-tale signatures that helped the researchers decipher what the animals ate in the lead up to their death. The team said the most difficult part was differentiating between the signatures of the fat molecules of the creatures themselves, the algal and bacterial remains in their guts, and the decaying algal molecules from the ocean floor that were all entombed together in the fossils.
The analysis confirmed the slug-like organism, known as Kimberella, had a mouth and a gut and digested food the same way modern animals do. The researchers say it was likely one of the most advanced creatures of the Ediacarans.
The team found that another animal, which grew up to 1.4 meters in length and had a rib-like design imprinted on its body, was less complex and had no eyes, mouth or gut. Instead, the odd creature, called Dickinsonia, absorbed food through its body as it traversed the ocean floor.
“Our findings suggest that the animals of the Ediacara biota, which lived on Earth prior to the ‘Cambrian Explosion’ of modern animal life, were a mixed bag of outright weirdos, such as Dickinsonia, and more advanced animals like Kimberella that already had some physiological properties similar to humans and other present-day animals,” said Bobrovskiy.
Bobrovskiy retrieved both the Kimberella and Dickinsonia fossils from steep cliffs near the White Sea in Russia—a remote part of the world home to bears and mosquitoes—in 2018.
Information provided by Australian National University.