Scientists have recently found oddly spindle-shaped microfossils in 3 billion year old rock in Australia.“It is surprising to have large, potentially complex fossils that far back,” said study lead author Prof Christopher House from Penn State University.

The microfossils are reported to be planktonic autotrophs who were approximately twenty to sixty microns in length– and freely floated through out the ocean producing energy, according to the study published in the journal Geology. The researchers looked at surrounding rocks (Farrel Quartzite) to determine the age of the fossils, and came up with their stable carbon isotope ratios.

The ratio of Carbon 13 (The component used to determine the age of life by measuring the half-lives of isotopes) was indicative of life. Life forms throughout life gather up more carbon 12 to incorporate into themselves which creates a certain signature of biological processes. Researchers looked at surrounding rock to determine if it was a fluke, and indeed the surrounding area was different from the microfossils.

“The spindles appear to be the same as those found in rocks from the Strelly Pool Formation in Western Australia and the Onverwacht Group in South Africa and Swaziland that are both 3.4 billion years old,” said co-author Dr Dorothy Oehler from Astromaterials Research and Exploration Science Directorate, NASA – Johnson Space Center.

“The existence of these microfossils in diverse locations as far back as 3.4 billion years ago suggests that the oceans probably had life in them for a very extended period of time. Moreover, this has implications beyond what we have done here, suggesting the evolution of diverse life proceeded quickly.”

“When considered along with published morphological and chemical studies, these results indicate that the Farrel Quartzite microstructures are bona fide microfossils, and support the interpretation that the spindles were planktonic.”

Citation:

Bibliographic information: C.H. House et al. Carbon isotopic analyses of ca. 3.0 Ga microstructures imply planktonic autotrophs inhabited Earth’s early oceans. Geology, vol. 41, no. 6, p. 651-654; doi: 10.1130/G34055.1

http://www.sci-news.com/paleontology/article01136-plankton-microfossils-australia.html