Dinosaurs Had Freezing Temperatures During the Cretaceous

Gregory Price from the University of Plymouth, UK and Elizabeth Nunn from Johannes Gutenberg University Mainz, Germany, discovered that there was a severe drop in the Earth's temperature, 137 million years ago, during the warm and balanced climate of the Cretaceous Period.

As a result, the water temperature of the Arctic Ocean fell from 13ºC to between 4 and 7ºC, and there is a chance that the poles froze over.

The scientists investigated rock samples with fossil belemnites and glendonites from Svalbard in an attempt to find out what was thee temperature of the Arctic Ocean between 140 and 136 million years ago.

This kind of research helps predict climate and environmental evolutions and allows scientists to better understand the humans' impact on climate.

During the Cretaceous Period, the weather was warm, with higher carbon dioxide levels than today, and scientists have speculated that there must have been colder periods.

Price and Nunn's latest research proves that there was a brief cold episode approximately 137 million years ago, when “temperatures fell drastically compared with the average water temperatures of 13ºC or even 20ºC in the Arctic region during the rest of the Cretaceous Period.”

Nunn says that the polar regions were inhabited by dinosaurs during the Cretaceous greenhouse period but as the colder weather rushed in, and marine reptiles could have migrated towards warmer areas, it is uncertain for researchers how dinosaurs would have survived the harsh conditions.

The two scientists analyzed rock outcrops on Svalbard and found rock layers from the Valanginian Stage of the Lower Cretaceous, rich in belemnites - fossils reminiscent of modern squid, and glendonites - calcium carbonate crystal aggregates, from the time that the area was still a flat sea.

They can use the relics to find the link between two oxygen isotopes and find out the water temperature, because “if global temperatures fall, the oxygen isotope O16 is increasingly incorporated into polar ice and the isotope O18 is consequently enriched in the seawater relative to O16,” says Nunn, “and this ratio is stored within belemnites and glendonites.”

Dr Elizabeth Nunn is currently carrying out a study to find out whether, during the Early Cretaceous interval occurred seasonal temperature fluctuations, AlphaGalileo reports.