The Role of Prehistoric Worms in Earth’s Biodiversity Explosion

The study conducted by Johns Hopkins University researchers sheds new light on the significant role that prehistoric worms and other invertebrates played in sparking a chain of events that led to the Great Ordovician Biodiversification Event, which occurred approximately 480 million years ago. These small creatures, which no longer exist today, were found to have altered evolutionary history in a profound way through their digging and burrowing activities along ocean bottoms.

To better understand how changes in oxygen levels influenced large-scale evolutionary events, the researchers updated models detailing the timing and pace of increasing oxygen over hundreds of millions of years. By examining the relationship between sediment mixing caused by digging worms and the formation of pyrite, a mineral crucial for oxygen buildup, they were able to gain insights into early ocean conditions. The study found that sites with sediment mixing had significantly more pyrite than those without mixing, challenging previous assumptions about the impact of burrowing animals on oxygen levels.

The study compared the depth of sediment mixing to the formation of pyrite and its interaction with oxygen levels. Researchers found that a delicate balance is required for the buildup of pyrite – too little mixing prevents oxygen from entering the sediment, while too much mixing results in the destruction of pyrite. This ‘Goldilocks’ scenario is essential for the formation of pyrite and the subsequent rise in oxygen levels that played a crucial role in the evolution of Earth’s biodiversity.

The new relationship between pyrite formation and sediment mixing revealed in the study has significant implications for understanding oxygen levels throughout Earth’s history. By applying this new data to existing models, researchers found that oxygen levels remained relatively stable for millions of years before experiencing a steep rise during the Ordovician period. This finding suggests a direct correlation between oxygen levels and pivotal moments in Earth’s evolutionary history when biodiversity flourished.

The study highlights the often-overlooked impact of small and seemingly insignificant creatures, such as prehistoric worms, on Earth’s biodiversity and evolutionary trajectory. By unraveling the complex interplay between sediment mixing, pyrite formation, and oxygen levels, researchers have provided valuable insights into the mechanisms driving major evolutionary events in Earth’s history. This research opens up new avenues for exploring the role of elemental cycles in shaping the planet’s biodiversity and underscores the importance of studying seemingly minor organisms in the grand scheme of Earth’s evolutionary story.