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article imageDinosaur extinction the result of 'perfect storm' of events

By Robert Myles     Jul 28, 2014 in Science
Edinburgh - And if that perfect storm hadn’t come about, say scientists, dinosaurs might still be with us today — except their continued existence might have meant a very different "us" having evolved — if at all.
According to new research from a clutch of British Universities and the world’s top dinosaur museums, sheer bad luck wiped out the dinosaurs. Had the asteroid strike marking their downfall occurred a smidgen earlier or later in history, the dinosaurs might have survived and continued to stalk the Earth.
The new study, a joint effort by the Universities of Edinburgh and Birmingham in collaboration with the University of Oxford, Imperial College London, Baylor University, and University College London and drawing on the resources of The Natural History Museum, the Smithsonian Institution, the Royal Ontario Museum, the American Museum of Natural History and the New Mexico Museum of Natural History and Science, used up-to-date fossil records and improved analytical tools to help palaeontologists build a new scenario of how these prehistoric creatures met their end some 66 million years ago.
Their research points to Earth experiencing environmental upheaval in the few million years before what’s reckoned to be the dinosaurs’ nemesis, a 10 kilometer wide asteroid, smashed into what is now Mexico. Prior to that life-terminating event, Earth underwent a period of extensive volcanic activity, changing sea levels and varying temperatures.
These terrestrial factors contributed to a deterioration of the dinosaurs' food chain. The turmoil Earth was undergoing meant less species diversity than would otherwise have been the case among the large plant-eating dinosaurs on which their carnivorous cousins preyed.
The environment, it seems, was just as crucial factor in maintaining species diversity 66 million years ago as it is today.
These environmental factors, with their knock-on effects on the dinosaurs’ food chain created a perfect storm meaning that dinosaurs’ resilience was diminished before the asteroid even hit. The asteroid event provided the tipping point so that the dinosaurs, in their already weakened state, were unlikely to survive.
The asteroid impact, other research having identified ground-zero as the giant Chicxulub crater under Chicxulub on the coast of Yucatán, Mexico, would have cost a host of environmental events including tsunamis, earthquakes, wildfires, sudden temperature swings and other environmental changes.
The result was collapsing food chains with dinosaurs suffering a domino effect: as one species was wiped out so the next dependent species was in the firing line for ceasing to exist.
The only dinosaurs that survived such a calamitous series of events were those that could fly. Those avian dinosaurs would eventually evolve to become the precursors of today’s birds.
The research raises the possibility that the dinosaurs could have survived had the Yucatan asteroid struck a few million years earlier. Then, the range of dinosaur species was more diverse and food chains were more robust.
If the asteroid had chanced upon Earth at a later date, new species of dinosaur would have had time to evolve and these more advanced species, very likely, would have survived, according to the researchers.
Scotland’s University of Edinburgh led the research part of which involved studying an updated catalogue of dinosaur fossils, mostly from North America, to paint a picture of how dinosaurs changed over the few million years before the asteroid struck. Other related studies are ongoing in Spain and China which, it’s hoped, will provide an even better understanding of precisely what took place of what’s known as the Cretaceous–Paleogene or ‘K–Pg’ extinction event.
Illustrating how the unlucky dinosaurs just happened to be in the wrong place at the wrong time, Dr Steve Brusatte, of the University of Edinburgh's School of GeoSciences, commented, "The dinosaurs were victims of colossal bad luck. Not only did a giant asteroid strike, but it happened at the worst possible time, when their ecosystems were vulnerable. Our new findings help clarify one of the enduring mysteries of science."
Co-author of the study, Dr. Richard Butler of the School of Geography, Earth and Environmental Sciences at the University of Birmingham, said there was nothing inevitable about the dinosaurs dying out, adding, "There has long been intense scientific debate about the cause of the dinosaur extinction. Although our research suggests that dinosaur communities were particularly vulnerable at the time the asteroid hit, there is nothing to suggest that dinosaurs were doomed to extinction. Without that asteroid, the dinosaurs would probably still be here, and we very probably would not."
The dinosaurs’ death-knell caused an evolutionary vacuum that led to the rise of mammals and, ultimately, humanity, according to Dr Brusatte, interviewed by BBC News. If the asteroid had taken a different course and missed Earth, exactly when it did, we’d be living in a dinosaur dominated world.
"Except that we would not be here because mammals would not have had the opportunity to blossom and we would not be having this conversation!" he added.
Phew! It’s an extremely uncharitable asteroidal harbinger of doom that brings no-one any good.
The study, published in Biological Reviews, was supported by the US National Science Foundation and the European Commission.
More about Extinction event, mass extinction, Evolution, Dinosaurs, Geoscience
 
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