(CNN)Microfossils found in China have revealed what could be our earliest known ancestor on the tree of life, researchers say. But don’t go looking for a resemblance. Saccorhytus, which looks a little like the “chestburster” from “Alien,” was a tiny, bag-like sea creature that lived 540 million years ago.
With a scientific name describing the shape of its body and wrinkled appearance, this millimeter-long creature wriggled around in the mud and lived between grains of sand on the seabed, according to a study published Monday in the journal Nature. Though the fossils were found on dry land, half a billion years ago, the creature’s location would have been a shallow sea.
Biologically, Saccorhytus belongs to a broad category of creatures called deuterostomes. Half a billion years ago, they began to rapidly evolve into diverse branches, including vertebrates such as humans as well as sea squirts, starfish, sea urchins and acorn worms.
Both were part of the Cambrian “explosion,” the sudden appearance of a wide variety of animal life in the fossil record half a billion years ago and an important turning point in the evolution of life on Earth, Harvey said.
“They help us to reconstruct the ‘tree of life,’ the series of branching events in animal evolution,” Harvey said. “But aside from that, they reveal that soon after the origin of animals in the late Precambrian, some groups of animals were already adapting to the ‘extreme’ lifestyle of living between grains of sand on the seabed, possibly as protection from being eaten by bigger animals.”
Modern-day loriciferans haven’t evolved much. They can still be found in their tiny ecosystem within beach sand or sea sediment. And loriciferans don’t belong to “our” part of the tree of life.
The researchers “do point out that Saccorhytus belongs to the same ‘branch’ of the tree of life as humans — so could be seen as one of our early human ancestors!” Harvey said. “Funny to think, but in half a billion years, a lot of evolutionary changes can take place.”
Could Our Earliest Ancestor Be This Ancient Sea Creature?
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