The evolutionary history of Earth is marked by periods of rapid biodiversity growth, with one of the most significant bursts dating back to roughly 480 million years ago during the Great Ordovician Biodiversification Event. A recent study conducted by researchers at Johns Hopkins University suggests that this explosion of new species may have been catalyzed by the humble actions of prehistoric worms and other invertebrates.
Contrary to common assumptions, the digging and burrowing of these small creatures along ocean bottoms played a crucial role in releasing oxygen into the ocean and atmosphere. The study, published in the journal Geochimica et Cosmochimica Acta, reveals how the mixing of sediment caused by digging worms interacted with a mineral called pyrite to contribute to oxygen buildup over millions of years.
Lead author Maya Gomes, an assistant professor in the Department of Earth and Planetary Sciences, highlights the significance of this research in reexamining early oceans’ chemistry. By updating models that track the evolution of oxygen levels, the team was able to challenge previous assumptions and shed light on the complex interactions between sediment mixing, pyrite formation, and oxygen accumulation.
The study introduces the concept of “Goldilocks conditions” – where sediment mixing must strike a delicate balance to allow for the buildup of pyrite without being destroyed by oxygen. Through analyzing pyrite levels in nine sites along a shoreline in Maryland, the researchers found that even minimal sediment mixing could lead to a significant increase in pyrite formation, ultimately contributing to rising oxygen levels.
By applying this new understanding of the relationship between sediment mixing and pyrite formation to existing models, the researchers were able to trace the fluctuations in oxygen levels throughout Earth’s history. The findings suggest that oxygen levels remained relatively stable for millions of years before experiencing a sharp rise during the Ordovician period, coinciding with the Great Ordovician Biodiversification Event.
The study underscores the critical role played by prehistoric worms in shaping Earth’s evolutionary trajectory. By elucidating the intricate mechanisms behind oxygen buildup and biodiversity explosions, researchers have added a new dimension to our understanding of life’s history. As we continue to unravel the mysteries of our planet’s past, studies like these offer a glimpse into the profound impact that seemingly insignificant creatures can have on the course of evolution.
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