Geochemist Jochen Brocks and colleagues report they discovered the earliest molecular footprints of eukaryotes, dating back 1.6 billion years, in this Barney Creek rock formation in northern Australia.
Molecular fossils found in ancient sedimentary rocks have unveiled a lost world of primitive eukaryotes that dominated aquatic ecosystems from at least 1.6 billion to 800 million years ago.. The majority of these molecules, which form in the process of creating steroids, were likely produced by primordial eukaryotes, relatively complex life-forms that today include animals, plants, algae and fungi, the researchers say.
“This study explains why we don’t see footprints of these guys in the rocks, as researchers were looking for the wrong thing,” says biologist Laura Katz, a biologist at Smith College in Northampton, Mass., who was not involved with the new work. “It fills a void in the fossil records.” To test this, geochemist Jochen Brocks of the Australian National University in Canberra and colleagues artificially matured molecules made in the first few steps of steroid biosynthesis, including lanosterol and cycloartenol. That revealed what the compounds’ molecular fossils would look like. Then the researchers looked for these fossils in tarlike bitumens and oils extracted from ancient rocks from all over the world.
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