Finding Fossils from Earth's Early History
A new study provides insight into assessing the authenticity of putative remnants of life from the Precambrian Period on Earth. The Precambrian constitutes the majority of Earth’s history, spanning from the formation of the the planet roughly 4.6 billion years ago to 541 million years ago. Astrobiologists have long sought to identify fossils of life from this period, which would provide important data points in the history of life’s origin and evolution on our planet.
Numerous studies have focused on identifying remnants of life from Precambrian samples. This includes attempts to identify biological organic matter associated with ‘microfossils’ putatively left behind by ancient microorganisms. A team of scientists recently used nano-scale Secondary Ion Mass Spectrometry (NanoSIMS) to gather geochemical data at the scale of individual microfossils, examining whether analytical biases of the technique are strong enough to interfere with the identification of degradation products left behind by organic matter. Their paper reports results from NanoSIMS investigations of the geochemical composition of organic-walled microfossils from the early Neoproterozoic Liulaobei Formation in North China.
The study is the first to demonstrate how NanoSIMS can be used to track ancient precursors of organic matter, and could be a significant step in assessing putative traces of life found in materials from Earth’s earliest history. The paper, “Can NanoSIMS probe quantitatively the geochemical composition of ancient organic-walled microfossils? A case study from the early Neoproterozoic Liulaobei Formation,” was published in the journal Precambrian Research. The work was supported in part by NASA Astrobiology through the Exobiology Program.