Did dinosaurs get hot? What were your summers like? In order to reconstruct the climate of the prehistoric past at the station level, a team of international scientists led by Niels de Winter of the Vrije Universiteit Brussel (Belgium) have developed an innovative way of using the grouped isotope method for this purpose (the isotopes they are atoms of the same element with different masses). The results indicate that dinosaurs had to deal with hotter summers than we thought.
Dinosaurs suffered seasonal changes
Their results, accurately reconstructing monthly sea surface temperatures at around 50 ° N latitude from fossil shells of bivalve mollusks that lived during the Campanian greenhouse period, about 78 million years ago, suggest that in In mid-latitudes, seasonal temperatures were likely to rise along with global warming, which would have resulted in really high summer temperatures.
“We used to think that when the climate warmed up like it did in the Cretaceous period, the time of the dinosaurs, the difference between the seasons would decrease, just as today’s tropics experience less difference in temperature between summer and winter. However ” Our reconstructions now show that the average temperature did increase, but that the temperature difference between summer and winter remained fairly constant. This leads to hotter summers and warmer winters than we thought.”
The fossil shells used in the study were very well preserved and came from southern Sweden, from ancient coastal towns in the Kristianstad basin, during the Cretaceous; They grew in the warm, shallow seas that covered much of Europe at the time. They recorded monthly variations in their environment and climate, like the rings on a tree.
What was the temperature?
Using a “clustered isotope” method, they found that water temperatures fluctuated between 15 and 27 degrees Celsius, more than 10 degrees warmer than today. “It was thought that during the age of the dinosaurs the difference between the seasons was small,” says Winter.
The team also worked with scientists at the University of Bristol (UK) who developed climate models to compare the results with climate simulations from the Cretaceous period. The results were in perfect agreement with the Bristol models. This shows that the variations in the seasons and the chemistry of the water are very important in climatic reconstructions:
“It is very difficult to determine the climatic changes of so long ago on the seasonal scale, but the seasonal scale is essential to make the climatic reconstructions correct. If there is hardly any difference between the seasons, the reconstructions of the annual mean temperature turn out to be different from the situations when the difference between the seasons is large . It was thought that during the age of the dinosaurs the difference between the seasons was small. We have now established that there were greater seasonal differences . highest in the summer, “conclude the authors.
Referencia: Niels J. de Winter et al, Absolute seasonal temperature estimates from clumped isotopes in bivalve shells suggest warm and variable greenhouse climate, Communications Earth & Environment (2021). DOI: 10.1038/s43247-021-00193-9
