Newly published research suggests that volcanism did not play a major part in the mass extinction event that marked the end of the Mesozoic. Enormous volcanic eruptions resulting in the formation of the Deccan Traps had been considered a primary trigger for the Cretaceous–Palaeogene (K–Pg) mass extinction event. However, a new study suggests that the deposition of vast quantities of flood basalt did contribute to climate change but did not play a key role in the extinctions. For example, the primary driver of the non-avian dinosaur extinction was probably the Chicxulub impact event.
The extinction of iconic dinosaurs such as Tyrannosaurus rex was not due to the deposition of the Deccan Traps according to new research. Picture credit: Everything Dinosaur.
Picture credit: Everything Dinosaur
Research Led by the University of Manchester
Researchers – led by the University of Manchester analysed ancient peats from Colorado and North Dakota. They were able to reconstruct the average annual air temperatures in the 100,000 years leading up to the extinction. The team included scientists from Utrecht University (Netherlands), the University of Plymouth and the Denver Museum of Nature and Science (USA). Their data indicates that volcanic CO₂ emissions caused a slow global warming of about 3°C (Celsius) during this period. They also discovered that there was a short, cold “snap”, a cooling of about 5° Celsius that coincided with a major volcanic eruption approximately 30,000 years before the extinction event. This was likely due to volcanic sulphur emissions blocking out sunlight.
However, the team found that temperatures returned to pre-event values before the mass extinction, suggesting that, from the terrestrial perspective, volcanogenic climate change was not the primary cause of K–Pg mass extinction. In summary, the climate changes caused by the immense volcanic activity were not dramatic enough to cause the non-avian dinosaur extinction.
Commenting on the significance of the team’s findings, lead scientist Dr Lauren O’Connor (Utrecht University), stated:
These volcanic eruptions and associated CO2 emissions drove warming across the globe and the sulphur would have had drastic consequences for life on earth. But these events happened millennia before the extinction of the dinosaurs, and probably played only a small part in the extinction of dinosaurs.”
Volcanism Not Directly Linked to Dinosaur Extinction
Co-author Dr Rhodri Jerrett, (Senior Lecturer in Earth Sciences, University of Manchester) explained:
“By comparison, the impact from the asteroid unleashed a chain of disasters, including wildfires, earthquakes, tsunamis, and an “impact winter” that blocked sunlight and devastated ecosystems. We believe that it was the asteroid that ultimately delivered the fatal blow.”
The ancient fossil peats that the research team analysed contain specialised cell-membrane molecules produced by bacteria. The structure of these molecules is dependent on the temperature of their environment. An analysis of the composition of these molecules enabled the scientists to reconstruct past temperatures. The team built a detailed “temperature timeline” for the years preceding the non-avian dinosaur extinction.
Research team members mapping one of the layers of fossil peat analysed in the study. Left-to-right, Greg Price, Rhodri Jerrett and Lauren O’Connor conducting fieldwork at West Bijou. Picture credit: Tyler Lyson.
Picture credit: Tyler Lyson
Fellow author, Dr Tyler Lyson (Denver Museum of Nature and Science) added:
“The field areas are ~ 750 km apart and both show nearly the same temperature trends, implying a global rather than local temperature signal. The trends match other temperature records from the same time period, further suggesting that the temperature patterns observed reflect broader global climate shifts.”
Implications for Climate Change Researchers
This study helps scientists to understand how our planet responds to major disruptions. This type of research can provide fascinating information about past events, but also could help find ways to prepare for future climate changes or natural disasters.
The research team hope to be able to apply this novel research method to reconstruct past climates at other crucial times in our planet’s history.
Everything Dinosaur acknowledges the assistance of a media release from the University of Manchester in the compilation of this article.
The scientific paper: “Terrestrial evidence for volcanogenic sulfate-driven cooling event ~30 kyr before the Cretaceous–Paleogene mass extinction” by Lauren K. O’Connor, Rhodri M. Jerrett, Gregory D. Price, Tyler R. Lyson, Sabine K. Lengger, Francien Peterse and Bart E. van Dongen published in Science Advances.
The Everything Dinosaur website: Dinosaur Toys and Gifts.
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