Asteroid that killed the dinosaurs was 'good for bacteria'

Asteroid that killed the dinosaurs and nearly wiped out all life on Earth was good for bacteria and caused it to flourish, study claims

  • An asteroid impact 66 million years ago was enough to ‘stop photosynthesis’
  • It killed the dinosaurs and wiped out about 75 per cent of all species on Earth
  • Researchers found evidence of bacteria at the impact site soon after it hit 

The asteroid that killed the dinosaurs and nearly wiped out all life on Earth was good for bacteria and caused it to flourish, study claims.

A team of researchers from Curtin University in Australia studied rocks and soil inside the Chicxulub crater left behind by the dino-killing asteroid.

Remains of plants, fungi and microbes were found in the crater samples – likely transported on waves from a giant tsunami after the impact.

Evidence of blue-green algae was found sitting on top of the dead layer of plans and fungi and it likely formed a few years after the initial crash. 

This shows the resilience of microorganisms to bounce back after ‘abnormally hostile conditions’, according to lead author Bettina Schaefer.

Researchers say the impact caused a tsunami and put debris into the atmosphere, all within the first day. The tsunami put a bed of plants, fungi and microbes back into the crater that the green-blue algae developed on top of 

The impact of the giant space rock, about 66 million years ago, was intense enough to cause photosynthesis to shut down around the world. 

It moved 24 times faster than a bullet as it hit the Earth and the shockwave that resulted from the impact flattened trees and led to large forest fires. 

Nearly 75 per cent of all species went extinct as a result of the collision. 

At the point of impact, in the middle of the crater, the area was sterile – it was found nearly 20 miles deep in the Gulf of Mexico and not a thing could have survived.  

Before this study scientists had seen hints of early life in the crater, but the numbers were small, meaning a details picture couldn’t be captured.  

Ms Schaefer studied the preserved fats that are left behind by blue-green algae when they die, rather than look for solid fossil records.

The fats were found on top of a layer of fossilised plants washed into the crater by a tsunami, but below another layer of debris from the atmosphere. 

The team say this means the bacteria began to populate the crater after the tsunami hit but before the atmosphere had fully cleared of debris from the impact. 

‘When the dust from the asteroid’s impact settled and sunlight returned to ideal levels, there was a rapid resurgence of land plants, dinoflagellates, cyanobacteria and all forms of anaerobic photosynthetic sulfur bacteria,’ she said. 

More organisms moved in on top of the blue-green algae soon after, creating a richer environment, the team said.

This is an illustration of an asteroid approaching Earth, similar to the one that killed the dinosaurs about 66 million years ago

It is an example of just how fast life can return after a cataclysmic event. 

The research suggest that the phytoplankton communities in the post-impact crater basin continued to produce and evolve at a ‘rapid’ rate, according to John Curtin, founding director of Curtin’s School of Earth and Planetary Sciences.

‘The development and productivity of phytoplankton was accompanied by major transitions in nutrient and oxygen supplies that shaped the recovery of microbial life.’ 

‘There was so much going on in such a short time frame, it really was like a post-apocalyptic microbial mayhem was happening in the Chicxulub crater,’ said Curtin.

The research has been published in the journal Geology. 

WHY DID THE DINOSAURS GO EXTINCT?

Dinosaurs ruled and dominated Earth around 66 million years ago, before they suddenly went extinct. 

The Cretaceous-Tertiary extinction event is the name given to this mass extinction.

It was believed for many years that the changing climate destroyed the food chain of the huge reptiles. 

In the 1980s, paleontologists discovered a layer of iridium.

This is an element that is rare on Earth but is found  in vast quantities in space.  

When this was dated, it coincided precisely with when the dinosaurs disappeared from the fossil record. 

A decade later, scientists uncovered the massive Chicxulub Crater at the tip of Mexico’s Yucatán Peninsula, which dates to the period in question. 

Scientific consensus now says that these two factors are linked and they were both probably caused by an enormous asteroid crashing to Earth.

With the projected size and impact velocity, the collision would have caused an enormous shock-wave and likely triggered seismic activity. 

The fallout would have created plumes of ash that likely covered all of the planet and made it impossible for dinosaurs to survive. 

Other animals and plant species had a shorter time-span between generations which allowed them to survive.

There are several other theories as to what caused the demise of the famous animals. 

One early theory was that small mammals ate dinosaur eggs and another proposes that toxic angiosperms (flowering plants) killed them off.  

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