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Dated gene duplications elucidate the evolutionary assembly of eukaryotes - Nature
Analysis of eukaryotic gene sequences using a relaxed molecular clock methodology indicate that eukaryotes emerged 3.0–2.25 billion years ago as a result of mitochondrial endosymbiosis with complex archaea that already possessed an elaborated cytoskeleton, membrane trafficking, endomembrane, phagocytotic machinery and a nucleus.