Nearly 420 million years ago, Earth suffered a major mass extinction which was the reason for the wipe out of almost 23 per cent of the marine life on the planet. The reason for such extinction was always a subject for study and now the mystery has finally been unravelled.
The findings of the study which were published in the journal – Geology and the study was conducted by researchers from Florida State University. It states that it was triggered by an all-too familiar widespread depletion of oxygen in the global oceans.
The study co-author Seth Young, an assistant professor in the Department of Earth, Ocean and Atmospheric Science said, "This makes it one of the few extinction events that is comparable to the large-scale declines in biodiversity currently happening today, and a valuable window into future climate scenarios’’.
Scientists have long been aware of the Lau/Kozlowskii extinction as well as a related disruption in Earth's carbon cycle during, which the burial of enormous amount of organic matter caused significant climate and environmental changes. But the link and timing between these two associated events -- the extinction preceded the carbon cycle disruption by more than a hundred thousand years -- remained stubbornly opaque.
"It has never been clearly understood how this timing of events could be linked to a climate perturbation, or whether there was direct evidence linking widespread low-oxygen conditions to the extinction," said Chelsie Bowman, FSU doctoral student, who led the study.
Researchers used advanced geochemical methods including thallium isotope, manganese concentration, and sulfur isotope measurements from important sites in Latvia and Sweden to reconstruct a timeline of ocean deoxygenation with relation to the Lau/Kozlowskii extinction and subsequent changes to the global carbon cycle.
The team's new and surprising findings confirmed their original hypothesis that the extinction record might be driven by a decline of ocean oxygenation.