Hace 252 million years, Earth went through the largest mass extinction in its history, an event that completely reshaped the oceans and marked the beginning of modern marine ecosystems.
The disappearance of a large portion of species drastically reduced biodiversity and reorganized the distribution of life, affecting the connection between seas and the evolution of the organisms that inhabited them.
An empty and homogeneous ocean
After the crisis, the oceans were left empty and homogeneous, ready for new forms of life to emerge. Only a few species were able to expand globally, while most disappeared.
This phenomenon led to a phase of biological cosmopolitanism, in which the seas shared similar communities across the planet.
The study by the Universitat de València and CONICET
Researchers from the Universitat de València (UV) and CONICET-Argentina analyzed this phase of marine life re-expansion using a very common group in the fossil record: the bivalves, relatives of today’s clams and mussels.
The aim was to determine whether the marine communities that existed before the extinction managed to persist or if new community groups emerged. The results show that, over time, especially during the Middle Triassic, new species appeared and large biological regions began to differentiate, such as the Tethys Ocean (precursor of the Mediterranean) and the Pacific, each with characteristic fauna.
Reconstruction of marine communities
The research used an extensive global database and network analysis tools, similar to those used to study social or internet connections. This allowed the reconstruction of how organisms organized and dispersed after the extinction.
The work demonstrates that marine ecosystems took millions of years to recover, and that the mass extinction not only eliminated species but also redefined the rules of evolution in the oceans.
Consequences of the mass extinction
Among the most relevant effects are:
- Homogenization of the oceans, with similar communities in different regions.
- Global expansion of a few resilient species, like some bivalves.
- Subsequent differentiation of biological regions, with characteristic faunas in Tethys and the Pacific.
- Slow recovery, which took millions of years to re-establish complex ecosystems.
Funding and scientific relevance
The research was partially funded by public grants from the State Program for Knowledge Generation and Scientific and Technological Strengthening of the R&D&I System, and the State R&D&I Program Oriented to Societal Challenges, within the framework of the State Plan for Scientific and Technical Research and Innovation.
This study not only provides information about Earth’s distant past but also offers insights into how mass extinctions reorganize life and how ecosystems can respond to global environmental crises.
The mass extinction 252 million years ago left the oceans empty and homogeneous, but it also paved the way for the emergence of new species and the differentiation of biological regions. The work by the UV and CONICET demonstrates that biological crises not only destroy but also reconfigure life, laying the foundations for the ecosystems we know today.
