Scientists have discovered tiny fossil shells that unveil details about the Earth’s climate over half a billion years ago.
About the study;
- That early animals diversified within a climate similar to that in which the dinosaurs lived.
- An international collaboration of scientists, led by the University of Leicester in the UK, has investigated by combining climate models and chemical analyses of fossil shells about 1mm long. This interval in time is known for the ‘Cambrian explosion’, the time during which representatives of most of the major animal groups first appear in the fossil record.
- Scientists have long thought that the early Cambrian Period was probably a greenhouse interval in Earth’s climate history, a time when there were no permanent polar ice sheets.
- Until now, however, scientists have only had a sense of what the Cambrian climate was like because of the types of rock that were deposited at this time – while it has long been believed that the climate was warm, specific details have largely remained a mystery.
- Data from the tiny fossil shells, and data from new climate model runs, show that high latitude ( about 65 degree South) sea temperatures were in excess of 20 degrees C. This seems very hot, but it is similar to more recent, better understood, greenhouse climates like that of the Late Cretaceous Period.
- In this study oxygen isotope ratios was used, which is a commonly used palaeothermometer. We then used acid to extract fossils about 1mm long from blocks of limestone from Shropshire, UK, dated to between 515-510 million years old.
Climate model simulations
- Many marine animals incorporate chemical traces of seawater into their shells as they grow.
- That chemical signature is often lost over geological time, so it’s remarkable that we can identify it in such ancient fossils.
- The climate model simulations also suggest that Earth’s climate was in a ‘typical’ greenhouse state, with temperatures similar to more recent, and better understood, greenhouse intervals in Earth’s climate history, like the late Mesozoic and early Cenozoic eras.