Very Early Animals Were Already Forming Social Networks

These rangeomorph fossils are thought to be the remains of some of the first macroscopic animals. They have been found to be connected by thin filaments but we don't yet know why. University of Cambridge

Filaments connect some of the oldest fossilized animals ever found, showing that even half a billion years ago our ancestors understood the value of networking. These threads' purpose can not be established – at least so far – but they indicate very early animals were cooperating with their neighbors in some way.

The first life was microscopic. The shift to larger organisms living in communities happened in the later Ediacaran period, 571-539 million years ago. The first part of that timespan was dominated by rangeomorphs, lifeforms that looked a little like ferns and grew up to 2 meters (7 feet) high. Although they lacked apparent mouths or other organs and were rooted to one spot on the seafloor, rangeomorphs are thought to have been among the first animals. The closest living equivalents might be corals that absorb nutrients from surrounding waters.

"These organisms seem to have been able to quickly colonise the seafloor, and we often see one dominant species on these fossil beds," Dr Alex Liu of Cambridge University said in a statement. How they did this has puzzled scientists so far.

Artist's impression of a forest of rangeomorphs. Charlotte Kenchington

In Current Biology, Liu reports the presence of threads running between rangeomorph fossils from Newfoundland. The filaments, mostly 2-40cm (0.8-16 inches) long, but in some cases stretching to 4 meters (13 feet), have been found at five sites. Liu and co-authors think they may have been a universal feature of rangeomorph communities, but the thinness of the threads, 0.01-0.1 centimeters (0.004-0.04inches inches) wide, means they can only be seen at the best-preserved sites. Some branch or appear bundled together before radiating outwards.

Although the purpose of this connecting web remains unknown the authors have plenty of theories. Strawberries use something similar for clonal reproduction, but if that was the only purpose we would not expect to see them running between rangeomorphs of similar size, as has been found.

Rangeomorph fossils with filaments between their bases. University of Cambridge

An alternative possibility is the filaments were a kind of anchor, with these plucky pioneers holding onto each other to best resist currents and storms great enough to disturb the deep.

Nutrient sharing, such as the recently discovered “wood wide web” used by modern trees, is another possible explanation, and this rangeomorph forest threading may have served multiple purposes.

"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," Liu said. "We may now need to reassess earlier studies into how these organisms interacted, and particularly how they competed for space and resources on the ocean floor.”

Irrespective of the primary reason, the finding emphasizes that, right from the beginnings of animal development, we stood or fell together.

Rangeomorphs against sandstone. University of Cambridge

 

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