New Discovery of Microfossils in Ancient Rocks Provides Earliest Evidence of Photosynthesis on Earth
A recent discovery of tiny fossils dating back nearly 2 billion years is shedding new light on the emergence of photosynthesis on Earth. The fossils, which are believed to be fossilized cyanobacteria, were found in the McDermott Formation in the desert of northern Australia. These small structures, known as thylakoids, are found inside the cells of photosynthetic organisms and contain the pigment chlorophyll, used to absorb light for photosynthesis. This discovery represents the earliest direct evidence for photosynthesis, providing a new tool for understanding early Earth ecosystems and the emergence of life on our planet.
“Our study provides direct evidence for the presence of metabolically active cyanobacteria performing oxygenic photosynthesis,” writes a team led by paleomicrobiologist Catherine Demoulin of the University of Liège.
The findings suggest that a detailed analysis of other fossils could identify more structures like thylakoids, pinpointing the moment photosynthesizing structures were utilized by the earliest forms of complex algal cells.
Photosynthesis, which converts water and carbon dioxide into glucose and oxygen using sunlight, is fundamental to the survival of most living things. It forms the foundation of most food webs and is responsible for filling the atmosphere with breathable oxygen.
The discovery of these microfossils challenges previous understandings of the emergence of photosynthesis, extending the fossil record of thylakoids back by 1.2 billion years. It suggests that oxygenic photosynthesis must have evolved before that time, but it remains unclear whether it contributed to the Great Oxidation Event, where oxygen levels suddenly skyrocketed some 2.4 billion years ago.
The research, published in Nature, provides new insights into the early evolution of photosynthesis and the emergence of complex cells in weakly oxygenated ecosystems. Further analysis of well-preserved microfossils could expand our understanding of early Earth ecosystems and the development of life on our planet.