Jakarta –
The earliest evidence of photosynthetic structures dating back 1.75 billion years has been identified. This photosynthetic structure was found in the Navifusa majensis microfossil assemblage in Australia.
These photosynthetic structures are found in the cells of modern photosynthetic organisms which contain the pigment chlorophyll. This means that microfossils represent the oldest direct evidence of photosynthesis, providing new tools for understanding Earth’s early ecosystems and how life emerged on our planet.
“Our study provides direct evidence for the existence of metabolically active cyanobacteria (bacteria that obtain energy from photosynthesis) that carry out oxygenic photosynthesis,” wrote researchers led by paleomicrobiologist Catherine Demoulin from the University of Liège, quoted from Sciencealert.
These findings suggest detailed analysis of other fossils could open up opportunities to study more such structures.
Photosynthesis is the basis for the survival of almost all living things. Photosynthetic organisms not only form the basis of most food webs. Their metabolic processes also fill the atmosphere with the oxygen most of us need to survive.
The Great Oxidation Event 2.4 Billion Years Ago
Early in Earth’s history, there was not much oxygen in the atmosphere and oceans. However, geochemical evidence reveals that oxygen levels suddenly spiked around 2.4 billion years ago in what is known as the Great Oxidation Event. It is not yet clear what the cause is, but one possibility is the emergence of photosynthetic organisms.
The earliest microfossil evidence of cyanobacteria is an organism called Eoentophysalis belcherensis, dated to 2,018 billion years ago. However, fossils are often difficult to interpret and their internal structures are not always intact. Apart from that, not all cyanobacteria species have thylakoids (membranes for photosynthesis).
Demoulin and his colleagues used different high-resolution microscopy techniques to investigate the external and internal structure of microfossils from a species known as Navifusa majensis, which is considered a cyanobacteria. In addition, in the bodies of single-celled organisms from two fossil layers, they found thylakoid membranes.
Photosynthesis May Have Evolved Before 1.75 Billion Years Ago
In their study, Demoulin and his co-authors discovered helpful photosynthetic structures in Navifusa majensis microfossils. Researchers identified it in fossils from three different locations, but the oldest comes from the McDermott Formation in Australia, 1.75 billion years old, namely the Paleoproterozoic era.
Quoted from Sci.News, the discovery of thylakoids in specimens from this era indicates that photosynthesis may have evolved before 1.75 billion years ago.
However, this does not solve the mystery of whether photosynthesis evolved before or after the Great Oxidation Event. Analysis of older microfossils may help answer this question and determine whether thylakoid evolution contributed to increased oxygen levels during the Great Oxidation Event.
“This discovery extends the thylakoid fossil record by at least 1.2 billion years and provides a minimum age for the divergence of thylakoid-bearing cyanobacteria of approximately 1.75 billion years ago,” the authors said.
“This enables the clear identification of early oxygenic photosynthesis and a new redox proxy for probing Earth’s early ecosystems, highlighting the importance of examining the ultrastructure of fossil cells to decipher their paleobiology and early evolution,” the authors added.
This research was published today in the journal Nature with the title “Oldest thylakoids in fossil cells directly evidence oxygenic photosynthesis”.
Watch the video “The appearance of damaged plants around the HI roundabout after the New Year celebration”
(nah/gas)
2024-01-08 13:30:25
#Plant #photosynthesis #thought #evolved #billion #years
