The tiny microbes behind one of the best-preserved fossils ever found

Among some of the most spectacular fossils unearthed are those found in strange locations, and new research is now showing that the way these fossils were preserved is far from what scientists originally thought.

According to an article on Phys.org, researchers at Curtin University discovered the factors behind why a 183-million-year-old ichthyosaur fossil has been able to preserve itself in full three dimensions rather than as an impression in rock. Based on their findings published on Phys.org, the researchers learned that the marine reptile fossil was able to preserve itself because of chemical processes and microbiology that took place following the death of the creature.

Microbes that build, not destroy

The research draws attention to an unexpected involvement of anaerobic bacteria, whose decomposition process resulted in the formation of sulfide minerals in the skeleton during its decomposition at the bottom of the sea. The researchers say that the crystals formed gradually in the internal structure of the bone, strengthening it and thereby preventing the collapse of the bones under the pressure of accumulating sediments.


As stated on Phys.org, "this made the ichthyosaur's bones rigid molds of their original shape in three dimensions.”

In conclusion, this discovery brings into focus another function of microbes, which are generally considered a cause for decay, but instead have proven to be instrumental in fossilization.

Why oxygen alone is not enough

It is known that, for decades, scientists believed that fossils had a higher chance of survival in low-oxygen environments, as it was believed that a lack of oxygen significantly delayed the the decay process. However, it is now shown that oxygen deficiency is not enough to ensure preservation.

It should be noted that according to the findings, microorganism activity is one of the decisive factors in deciding whether the fossil will remain in good condition and not disappear over time. In particular, it is stated that the activity of sulfur cycling microorganisms seems to play a crucial role, affecting mineral formation.

Therefore, fossils found in similar oxygen-deficient conditions may have different fates.

Evidence from other fossil sites

The observation of microbes having an impact on fossil formation is not unique to this one example alone. The same phenomenon has been witnessed in other fossils of marine reptiles, including Plesionectes longicollum, found in the Posidonia Shale Formation in Germany.

According to a ScienceDaily article, it has been observed that fossils like Plesionectes longicollum also have characteristics of exceptional three-dimensional preservation due to mineralization that is affected by microbes.

These repeated observations point toward the possibility of microbial involvement being common in fossil preservation rather than just a sporadic event.

How scientists uncovered the process

The scientists applied modern geochemical methods to determine the mineral structure of the bones, allowing them to determine the pathway of chemical transformations that resulted in the formation of fossils.

As Phys.org reports, such an approach made it possible for the researchers to establish the environmental conditions that prevailed at the time of fossilization and associate them with the metabolic processes of microorganisms.

In this way, it is possible to obtain a clear idea of the role of microscopic creatures in the formation of macroscopic fossils.

What this means beyond Earth

The ramifications of this discovery do not stop at Earth’s ancient seas. Experts think that learning more about the role of microbes in the preservation of minerals can aid the quest to find signs of life elsewhere, especially Mars, where there is a scarcity of oxygen, and abundant amounts of sulfates.

According to the Phys.org news article, the discovery offers a way to detect biosignatures, which are signs of biological activity, in samples from other worlds. Rather than searching for organic remnants alone, scientists might look for mineral formations produced by microbes.

Such an exploration strategy can change the way scientists seek out life on other planets in the future.

A new way to read fossils

This finding indicates that fossils should be understood not only as relics of prehistoric life forms but also as evidence of biological and environmental interaction after death. Thus, the introduction of the effect of microbes represents a new dimension that researchers need to take into account while studying fossils.

The new approach, which rejects the belief that the preservation process is dictated only by oxygen content, opens up new horizons for science. Future developments in this area are likely to bring further discoveries that would uncover the hidden mechanisms involved in the creation of fossils.

It turns out that the world of the smallest life forms holds the most important information about the distant past.