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Trending science: Badly timed asteroid may be responsible for dinosaur wipe out

They say that timing is everything in life. And new research has revealed that the ‘bad’ timing of an asteroid may have been responsible for killing off dinosaurs, ultimately, perhaps, making way for us humans.

The Guardian reports this week on an article in Biological Reviews which shows that the asteroid hit at a time when ecosystems had been weakened by a loss of biodiversity. If the asteroid had hit a few million years earlier, or a few million years later, dinosaurs might not have gone extinct.And we humans might not exist. The paper talks to Steve Brusatte, a paleontologist at Edinburgh University, who was part of an international team that reviewed the evidence on dinosaur extinction. He says that the dinosaurs might have survived the catastrophic impact that ended their reign had the devastating asteroid that slammed into the Earth arrived at a ‘more convenient time’. The asteroid slammed into the Earth around 66 million years ago in the area that is now Mexico. The impact triggered tsunamis, earthquakes and released enough heat to start many fires. The Guardian notes, ‘Material thrown into the air descended as acid rain, and also blocked the sun's warmth, cooling the Earth temporarily, perhaps by tens of degrees Celsius’. Nature magazine tells us that palaeontologists have argued for decades about whether dinosaurs were doing well when the asteroid hit, or whether they were on the decline. The new study pulled information from a database on global dinosaur diversity, including hundreds of fossils found in the past decade. The abstract from the article notes that impact occurred at a time of ‘reduced diversity of large-bodied herbivores’ which ‘perhaps making communities more susceptible to cascading extinctions’. It adds, ‘The abruptness of the dinosaur extinction suggests a key role for the bolide impact’. However , the abstract also acknowledges that ‘the coarseness of the fossil record makes testing the effects of Deccan volcanism difficult’. This point is picked up by the Guardian which points to the ‘huge gaps’ in dinosaur experts' knowledge: ‘There is only one site, the Hell Creek rock formation in the US, spread across Wyoming, the Dakotas and Montana, that has a good fossil record covering the final years of the cretaceous period. To round out the picture of the dinosaurs' fate, far more fossils from other regions are needed’. Although the cause of the extinction may not be completely settled, there is no doubt that it occurred quite suddenly en masse. As the study itself warns: ‘Dinosaurs are a cautionary tale that once-dominant groups of organisms can, and often do, die out. They vanished with many other species in one of the largest mass extinctions in Earth history.’For more information, please visit: http://onlinelibrary.wiley.com/doi/10.1111/brv.12128/abstract;jsessionid=6B482E4DAC0EF7B63D8CFAB6C5B48B6B.f04t03

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