470 million year old asteroid collision may have caused biodiversity burst on Earth

December 18th, 2007 - 3:06 pm ICT by admin  

Washington, Dec 18 (ANI): A new report by geologists suggests that a shattered asteroid may have sprayed Earth with high-speed debris 470 million years ago and spurred one of the biggest bursts of biodiversity in the planets history, rather than wiping life out.

The research was carried out by Birger Schmitz and his colleagues from the University of Lund, Sweden.

According to Discovery News, during the hypothesized period, an event called the Great Ordovician Biodiversification Event had occurred, when many new species of animals evolved. A period of moderate to heavy meteorite bombardment appears to match the time at which this event happened.

To make their argument, Schmitz and his team first pointed out research on meteorites that strongly suggests there was a major asteroid collision in the solar system about 470 million years ago.

Models suggest lots of debris, including large asteroid chunks, would be flying around the solar system for 10 to 30 million years after a big asteroid smashup, explained Schmitz. As evidence, the research team has collected evidence of widespread impacts in rocks of that age on Earth.

“These asteroids were particularly prone to enter Earth-crossing orbits,” said Schmitz.

That means they were quite prone to hitting Earth, and still are. The difference today, of course, is that there have been 470 million years for Earth to sweep up the bigger chunks of asteroid debris.

Yet, Earth is still being hit by smaller debris, known to meteorite researchers as the Flora family of asteroids, from the 470-million-year-ago asteroid event, Schmitz told Discovery News.

When the geologists went hunting for evidence of the bombardment in fossil-bearing rocks of the same age in the Baltic Scandinavia and China, they found it in the form of a telltale rise and fall in levels of extraterrestrial chromite and osmium isotopes in the rocks.

“They make an interesting point - that diversification often takes off when you destabilize a community of organisms, and/or disrupt their habitat,” said paleontologist Spenser Lucas, curator at the New Mexico Museum of Natural History and Science. “Everybody has filled up eco-space and reached a stable ecosystem, and then impacting objects could upset the balance — opening niches, creating new niches, etc,” he added.

But, according to Lucas, a lot more evidence is needed to truly causally link the bombardment with the biodiversity event.

“I think Schmitz, et al., have an interesting idea worth further evaluation,” said Lucas. (ANI)

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