Isolated community of complex life may have existed 2 billion years ago on Earth. Was life perhaps reinvented twice?

Amazing stuff! If confirmed, then this is huge! 

Why should the origin of life not have happened more than once?

"... Life appears to have gotten started pretty quickly after Earth formed about 4.5 billion years ago. Direct evidence shows that microbes were abundant by 3.5 billion years ago, with other fossils dating back 3.7 billion years. Other finds even suggest Earth could have been inhabited extremely quickly, as far as 4.3 billion years ago, though these fossils are heavily contested. ...
The researchers say that these favorable conditions would have been restricted to this inland sea – beyond that, Earth was still quite hostile to complex life. And even then, the oasis was short-lived, geologically speaking, and these creatures eventually went extinct. ..."

"But a team ... has discovered evidence of a much earlier ecosystem in the Franceville Basin near Gabon on the Atlantic coast of Central Africa over 1.5 billion years earlier. ...

Their study ... describes an episode of unique underwater volcanic activity following the collision of two continents, which created a nutrient-rich ‘laboratory’ for the earliest experiments in complex biological evolution. ..."

From the highlights and abstract:

"Highlights

• Paleoproterozoic seawater nutrient enrichment linked to hydrothermal weathering of a seafloor nutrient-rich reservoir.

• Nutrient enrichment triggered the onset of negative δ13C excursion in organic carbon in the Francevillian sub-basin.

• Nutrient enrichment initiated localized emergence of large colonial macrofossils in the Franceville sub-basin.

Abstract

It is thought that the global predominance of small-size unicellular prokaryotic life in the oceans until the emergence of large-size multicellular organisms to ecological dominance in the Ediacaran Ocean after 635 million years ago (Ma), was partly constrained by paleo-dynamic nutrient limitation, with phosphorus (P) being the principal limiting resource. Here we couple an episode of intense submarine hydrothermal alteration of a nutrient-rich seafloor reservoir to the collision of the Congo-São Francisco cratons at ∼2100 Ma, to unravel a paleo-geodynamic incident of seawater P enrichment in the Paleoproterozoic Francevillian sub-basin. We propose that this previously unrecognized local pulse in dissolved seawater P concentration, of comparable magnitude to Ediacaran seawater levels, set the stage for Earth’s earliest biospheric experimentation towards macrobiological complexity ∼2100 million years ago."

Isolated community of complex life may have existed 2 billion years ago "Scientists have discovered evidence that an isolated pocket of complex life may have evolved on Earth more than 2 billion years ago – only to go extinct and take another 1.5 billion years to evolve to that level again. The controversial find could rewrite our understanding of life on, and beyond, Earth."

Complex life on Earth began around 1.5 billion years earlier than previously thought, new study claims (original press release) "Environmental evidence of the very first experiments in the evolution of complex life on Earth, has been uncovered by an international team of scientists."

Hydrothermal seawater eutrophication triggered local macrobiological experimentation in the 2100 Ma Paleoproterozoic Francevillian sub-basin (open access)

Graphical abstract:

The team’s research provides strong validation for the biological affinity of the lobate macrofossils whose validity has been widely debated in the scientific community.