Fossils come in a variety of sizes. Microfossils are extremely small fossils that can be seen through a microscope. These microfossils shed light on when and how early life forms developed essential features, ultimately leading scientists to study the evolution of life.
Scientists must detect minute quantities of critical elements like phosphorus and molybdenum to analyze these microfossils. However, this is highly challenging.
Scientists from Tohoku University, in collaboration with experts from the University of Tokyo and Kochi University, have developed a new pioneering method for analyzing microfossils.
For this study, scientists particularly focused on 1.9-billion-year-old Gunflint microfossils, which are known as the ‘standard’ of microfossil study.
The team used a new method: placing the tiny fossils on a special glass slide. This allowed them to examine the fossils with light and electron microscopes.
ITO glass is a glass plate coated with a thin layer of indium tin oxide (ITO). Its transparency allows scientists to determine the internal structure of microfossils. Thanks to this new approach, scientists can precisely detect trace elements within the microfossils.
In simple terms, the team could see the natural phosphorus levels despite background noise. Since phosphorus is also found in sedimentary rocks, it was crucial to distinguish between the two.
The researchers used a device called NanoSIMS to overcome interference from elements in the rocks and the materials used to hold the fossils. This tool can image almost all aspects with high precision, better than one micron.
Their study showed that phosphorus was present along the edges of the microfossils, indicating that these ancient microorganisms already had phospholipid cell membranes like those in modern cells.
According to scientists, the presence of molybdenum within microfossil bodies indicates the existence of possible nitrogen-fixing metabolic enzymes.
This method helps us better understand how life evolved on Earth. It provides clear evidence of cell membranes and how ancient microbes lived.
This technique works not just on tiny fossils but also on old rocks with little organic material. It can even be used to study older geological times. It also looks at trace elements like copper, nickel, and cobalt to show how these organisms functioned.
These discoveries could change how we study early life and help answer big questions about where and when life began and how it developed on Earth.
Journal Reference:
- Kohei Sasaki, Akizumi Ishida, Takeshi Kakegawa, Naoto Takahata, Yuji Sano. Ultrahigh-resolution imaging of biogenic phosphorus and molybdenum in palaeoproterozoic gunflint microfossils. Scientific Reports, 2024; 14 (1) DOI: 10.1038/s41598-024-72191-8
