Mouthless Creatures Invented Social Network 500m Years Ago

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Ediacaran fronds, illustrative, 2020.
Ediacaran fronds, illustrative, 2020.Credit: Charlotte Kenchington

Facebook, be not proud. Social networking was invented over half a billion years ago by creatures that didn’t even have mouths or internal organs. These primitive creatures were called rangeomorphs and they interconnected by filaments that could stretch for meters.

Proof of interconnection between rangeomorphs using thread-like filaments was reported Thursday in Current Biology. Most of the filaments were between two and 40 centimeters in length, report researchers at the universities of Cambridge and Oxford, but some were as long as four meters.

The coast of Newfoundland, Canada, 2020.Credit: Dr Alex Liu

The filaments had been a secret to paleontologists until now because they’re so very thin. Yet under extraordinary conditions and serendipitous sedimentation in the primordial sea, they were preserved in the fossil record. Fossil rangeomorphs connected by length filaments were found on five sites in eastern Newfoundland, one of the world’s richest beds of Ediacaran fossils.

Yes, rangeomorphs were Ediacarans, early creatures that predate the life forms we know and love, and most looked nothing like any known animals, plants, fungi and so on. Rangeomorphs themselves specifically lived between about 571 million to 541 million years ago and looked like ferns, which absolutely does not mean they were ancestral to ferns.

The rangeomorphs were so primitive that they had no mouths, insofar as we can discern, and had no internal organs, insofar as we can tell. They seem to have been sessile. Yet they managed to reach enormous sizes, growing up to two meters in height as they swayed in the ocean currents on the sea floor.

Ediacaran fronds, illustrative, 2020. Credit: Dr Alex Liu

Their inability to move may be where their networking via thread-like filaments came into play. Lacking ingestion and digestion as we know them, the rangeomorphs may have absorbed nutrients from the seawater around them.

We think of social networking mainly as exchanging ideas, jokes and pictures of cats. But the paleontologists suspect rangeomorph networking may have been a way to share nutrients, which could help explain how they conquered the seabed. During their roughly 30 million years, rangeomorphs are believed to have become one of the dominant life forms on the ocean floor.

“These organisms seem to have been able to quickly colonise the sea floor, and we often see one dominant species on these fossil beds,” said Dr Alex Liu from Cambridge’s Department of Earth Sciences, and the paper’s first author. “How this happens ecologically has been a long-standing question – these filaments may explain how they were able to do that.”

An alternative explanation is that the filaments were the way the rangeomorphs procreated, a form of clonal reproduction (“like modern strawberries,” the scientists observe). However, they also noticed that organisms in the network seem to have been the same size, which argues for a different function.

Ediacaran fronds, illustrative, 2020. Credit: Dr Alex Liu

Ediacarans in general didn’t have skeletons or shells that would have been more easily preserved in the fossil record, but many did leave imprints in sediment that hardened into rock. Such fossils of early Ediacarans are especially abundant in the Mistaken Point fossil bed in Newfoundland, where these specimens were found.

“We’ve always looked at these organisms as individuals, but we’ve now found that several individual members of the same species can be linked by these filaments, like a real-life social network,” said Liu.

Sadly, the Ediacarans went extinct with the Cambrian explosion about 540 million years ago. The Cambrian beasties gradually replaced the mysterious but categorically weird Ediacaran life forms with definite animals, including predators that had eyes and legs, which are father and mother to us lot. If the Ediacarans left behind progeny that evolved into more familiar species, we don’t know about it.

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