Half billion-year-old ‘social network’ observed in early animals

The filaments ­­– some as long as four metres – connected organisms known as rangeomorphs, which dominated Earth’s oceans half a billion years ago. The team found these filament networks – which may have been used for nutrition, communication or reproduction –in seven species across nearly 40 different fossil sites in Newfoundland, Canada. 

“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 longstanding question – these filaments may explain how they were able to do that.” 

Fern-like rangeomorphs were some of the most successful life forms during this period, growing up to two metres in height and colonising large areas of the sea floor. Rangeomorphs may have been some of the first animals to exist, although their strange anatomies have puzzled palaeontologists for years; these organisms do not appear to have had mouths, organs or means of moving. One suggestion is that they absorbed nutrients from the water around them.

It’s possible that the filaments were used as a form of clonal reproduction, like modern strawberries, but since the organisms in the network were the same size, the filaments may have had other functions. For example, the filaments may have provided stability against strong ocean currents. Another possibility is that they enabled organisms to share nutrients, a prehistoric version of the ‘wood wide web’ observed in modern-day trees.  

“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. 

The team's results are reported in the journal Current Biology.