Roughly 66 million years ago, a 10-kilometre wide asteroid slammed against earth, wreaking all kinds of havoc.  

It is believed that this event was responsible for killing nearly three-quarters of all living species, including all non-flying dinosaurs.

Some researchers also believe this asteroid impact may have caused expansive fire storms that ravaged the planet, potentially playing a role in the massive extinctions. 

It's a controversial hypothesis that already has its critics. We know that when the asteroid hit off the coast of present-day Mexico, hot, melted rock would have been ejected way up into the sky. The question is, did these hot rocks have the energy and heat to spark wildfires once they landed? 

Over at the PLOS Blog, The Integrative Paleontologists, Shaena Montanari gives a good summary of the debate so far. 

As she points out, earth scientist Claire Belcher from the University of Exeter has previously argued that pieces of debris may have settled out of the atmosphere, forming something of a protective shield, or cloud, which guarded earth against extreme heat and fire.  

Other groups, however, argue that raining debris was still hot enough to cause fires, and point to charcoal imprints left in the geological record as evidence.   

A 2013 study lending support to this theory used computer models to calculate the "infrared radiation heat pulse" caused by the molten debris re-entering the atmosphere, and the probability that these hot rocks caused global wild fires. 

It suggested that these rocks could have caused temperatures blisteringly hot enough near the surface of the earth to ignite living plants, and solid wood. 

However, a new study by scientists at the University of Exeter and the University of Edinburgh in the UK (led by the aforementioned Claire Belcher), has again called this hypothesis into question - sort of

The researchers were able to combine computer simulations with actual fires in their lab to recreate the immense heat and energy of the asteroid collision. 

They found that, in the near vicinity of the impact, the immense heat would have been too short-lived (about one minute) to ignite living plants or cause major fires. 

However, their findings suggest that a less extreme heat lasting far longer (around seven minutes) would have been felt across oceans, and would have been sufficient enough to cause fires in those distant locations. 

"This has shown us that the heat was more likely to severely affect ecosystems a long distance away, such that forests in New Zealand would have had more chance of suffering major wildfires than forests in North America that were close to the impact," Belcher said in a press release.  

"This flips our understanding of the effects of the impact on its head and means that palaeontologists may need to look for new clues from fossils found a long way from the impact to better understand the mass extinction event."

The team has published its findings in the Journal of the Geological Society

It remains unclear whether fires - if they started as a result of the impact - played a role in the massive extinction event that occurred at the end of the Cretaceous period.

Most animals have strategies for dealing with and escaping fires, but if the heat was so severe that large animals couldn't take shelter, then it's possible fire might have been a factor.  

Another, more popular culprit is the decades-long "impact winter" that set in after the asteroid hit. 

Source: PLOS Blogs