It is well known that 65 million years ago the asteroid thought to have led to the extinction of the dinosaurs struck the Earth. Less well known is the fact that at this time the End-Cretaceous mass extinction also occurred. One of the five major mass extinctions in known history, it resulted in between 71 and 81 per cent of all species on Earth at that time being completely wiped out.
The asteroid impact is most commonly used as an explanation for this mass extinction, but whether or not other factors contributed has been an ongoing controversial topic. The rapid dinosaur extinction theory was based solely around fossil records in the West of America and Canada. Therefore, there was some speculation as to whether the asteroid could have caused a localised extinction when it struck Mexico, creating the Chicxulub crater.
However, recent evidence across Europe suggests that this extinction did in fact take place rapidly across the globe. Researchers from the Geology and Geophysics department of the University of Bucharest found that dinosaurs were still thriving in Europe – just as they were in North America, up until the end of the Cretaceous when they became extinct. This supports the theory that a diverse dinosaur population existed all over the planet until their swift extinction.
Brand new research conducted by the University of Edinburgh, University of Exeter and Imperial College London has shed a completely new light on the effects of the meteorite impact. Previously, it was thought that the collision caused firestorms to ravage the globe, resulting in the mass extinction.
Researchers recreated this event in a laboratory setting and discovered that the heat pulse created by the impact would have lasted less than a minute. They deduced that this time period would be significantly too short to set plant life alight.
This discovery is significant because it is the complete opposite of what was previously hypothesised. Areas further away, such as New Zealand, would have been affected for longer, although the heat would have been less intense.
Furthermore, it is thought that the ecosystems of these distant areas would have been more affected than those close to the impact due to the sustained heat. Scientists also believe that animals around the area of the impact would have been able to find shelter from fire, and plants would have been able to re-colonise other non-affected areas.
Other proposed contributors to the mass extinction are: high volcanic activity, a changing global climate and a decrease in sea levels. The high level of volcanic eruptions would have increased CO2 levels. This would most likely have caused ocean acidification, thereby polluting the food chain and causing the global temperature to rise.
These circumstances would likely have created an array of obstacles for the species living at that time. Therefore, it is now being suggested that the meteorite impact may not have had such a devastating impact for species under more favourable conditions. Rather, it may simply have been the final straw for these animals during a period of turmoil.
Date: FEBRUARY 10, 2015