Ancient Fossil Reveals Animal Life From 558 Million Years Ago

A gray rock showing marine fossils.
Susilull / Shutterstock

Science News revealed Thursday that researchers at Australian National University have identified a 558 million-year-old fossil, Dickinsonia, as an animal specimen. Previously, the fossil’s identity was never confirmed, but scientists had speculated that it was some sort of fossilized algae or lichen. However, the new study revealed the findings of cholesterol in these ancient fossils, which showed up during steroid studies on the specimen. Apparently, the high levels of cholesterol present in the Dickinsonia fossils are only found in animals — whose gut bacteria produces the substance — which led scientists to realize that they had just discovered the world’s oldest known animal.

The Dickinsonia fossils themselves are nothing new, Science News said. The fossils have been studied and debated over the course of the past 70 years. They are considered part of the fossil family called Ediacara biota. The name “Ediacara” comes from the place where they were first discovered — Edicaria Hills, Australia — and is also the name of the period which the biota belong to, the Ediacaran period.

Apparently, this life form is known to have thrived in the Precambrian Eon, and is known for its “alien-like” appearance. The specimens used in the reported study were taken from a remote, nearly untouched coast in northern Russia, by the White Sea. Because the area has been mainly undisturbed by human development or natural erosion, the samples continue to contain significantly more animal tissue than previous specimens found elsewhere.

The preserved remnants of organic tissue locked into the fossil was the key that helped scientists finally pinpoint the identity of Dickinsonia, says Science News. The organism is not similar to any others, so there had not really been much evidence from which to draw a conclusion in the past. Science Alert gives a little more insight into the particulars surrounding the discovery by sharing some key statements from the ANU research team.

“The fossil fat molecules that we’ve found prove that animals were large and abundant 558 million years ago, millions of years earlier than previously thought,” said one member of the team.

“Scientists have been fighting for [decades] over what Dickinsonia and other bizarre fossils of the Edicaran [sic] Biota were: giant single-celled amoeba, lichen, failed experiments of evolution or the earliest animals on Earth,” said another.

Dickinsonia fossils have been described to range in size from a few centimeters to 4.6 feet in length, Science Alert details. They are also described as having a strange, round, blob-like appearance with a ribbed texture. Ilya Bobrovskiy, ANU biogeochemist and head of the ANU study in question, credits the excavation of these new specimens in the untouched Russian region as key to the discovery.

“I took a helicopter to reach this very remote part of the world — home to bears and mosquitoes — where I could find Dickinsonia fossils with organic matter still intact,” said Bobrovskiy.