Half a billion years ago, our oldest animal ancestor made its worldly debut. New fossils have settled a decades-long debate, officially naming the Ediacaran biota the oldest-known animal.
Fossils of one type of Ediacaran, the Dickinsonia, were found way back in 1947.
But scientists have long debated just how far back those fossils went, and whether the organism qualified as an animal. It's tough to garner information from such ancient fossils, and some researchers believed that the Dickinsonia may have been something closer to an amoeba, algae or a lichen.
Recently, Jochen Brocks, a scientist with Australian National University, led a team that gathered 558-million-year-old fossils from the White Sea region of Russia.
And when they were able to take the time to break down those fossils, they realized that the organic material in them contained cholesterol, which today's animals still use to build their cell walls. Thus, they concluded it really was Earth's first animal, and their findings were recently published in the journal Science.
Perhaps unsurprisingly, the animal that lived half a billion years ago was nothing like the marine animals we know today. Scientists think they were pretty much underwater blobs.
The fossils that exist today suggest they were oval in shape, with bodies that looked somewhat like a large leaf. Scientists believe their heads were included in that oval shape rather than sticking out separately, and they also didn't have appendages. It's possible they had a slim digestive tract that flowed through their midsection.
And they got to be pretty big — some could get to be as much as 4.5 feet around, and they pretty much just kept growing until they eventually died.
Wikimedia/Stanton F. Fink
There's still a lot we don't know about the Dickinsonia, although we might learn more as scientists continue to scour the fossils.