(Image credit: Australian National University)
Scientists have found traces of the "world's oldest meal" in a species dating back 575 million years, a discovery they said sheds light on how our earliest animal ancestors functioned.
A team from the Australian National University studied Ediacaran period-fossils retrieved from Russia and attained astonishing insights.
They said the fossils contained remnants of a type of fat found in plants. That suggested to scientists that the creature ate algae and bacteria from the ocean floor.
Studying the traces also helped scientists confirm that the organism, known as Kimberella, had a gut and mouth and digested food like modern animals.
Researchers found another less advanced animal, called Dickinsonia, that absorbed food using its body.
Learning about these creatures is important because they represent "our deepest visible" roots, said Dr Ilya Bobrovskiy, the lead author of the study.
"They are oldest fossils large enough to be visible with your naked eyes, and they are the origin of us and all animals that exist today,"she added. "These creatures are our deepest visible roots."
For their project, researchers had to distinguish markers of the fat molecules of the animals, the algal and bacterial remains in their bodies and decomposing algal fragments the ocean floor that were all found together in the fossils.
Once they did that, they analysed Kimberella's gut molecules to ascertain its diet and digestion process.
"This was a Eureka moment for us; by using preserved chemical in the fossils, we can now make gut contents of animals visible even if the gut has since long decayed," co -author Professor Jochen Brocks said.
"We then used this same technique on weirder fossils like Dickinsonia to figure out how it was feeding and discovered that Dickinsonia did not have a gut," he added.