Geochemistry Shows Oldest “Fossils” Really Are Fossils – #365papers – 2018 – 6

Schopf, Kitajima, Spicuzza, Kudryavtsev, Valley, 2018, SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions: Proceedings of the National Academy of Sciences, v. 115, p. 53-58.

What’s it about?

The best evidence for the origins of life on this planet are geochemical signatures in rocks representing the metabolism of living organisms. Here, the authors show that the geochemical (isotopic) signatures directly correlate with what have been interpreted at the body fossils of primitive life forms, mostly bacteria.

Why does it matter?

This paper shows that what appear to be fossils in this 3.5 billion-year-old rock, really are fossils, disproving interpretations that propose origins with no biological influence. It shows also that there were relatively complex life forms 3.5 billion years ago. In addition, the authors show that there are at least three different kinds of organisms as well. Such a diversity suggest organisms that are adapted to specific environmental niches.

Why did I read this?

This SIMS method is one that I’ve wanted to apply to fossils in the past (not microfossils, but, for example, thin sections of mammal teeth), so naturally this caught my eye. It’s also interesting to learn about 3.5 billion-year-old body fossils of any kind.

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