The first animals on Earth didn't look the way we used to think

Dickinsonia fossils were last found more than 50 years ago. Science has since made impressive progress and scientists at the Australian National University have questioned the structure of one of the oldest species.

Dickinsonia are among the oldest inhabitants of the Earth, who lived about 558 million years ago. Disputes about what species these marine creatures should be assigned to still persist: some researchers believe that Dickinsonia are the ancestors of modern jellyfish, worms and even fungi. Scientists concurred on one point only: they believed that the ribbed imprints found more than half a century ago were traces of Dickinsonia’s bodies. But this fact has recently been challenged.

A group of scientists led by Ilya Bobrovskiy made an assumption that the ribbed imprints are casts of Dickinsonia skeletons or internal organs, while the actual creatures had a more complex structure.

This bold assumption makes us look at the old issue from a new angle, but there are still more questions than answers. Scientists now discuss which organs and systems of today’s animals did Dickinsonia actually have. So far, the team has only reached a consensus that the ancient animals’ tissue, whose traces were found, had different densities.