Seeking a Break in a 252 Million-Year-Old Mass Killing

A Geologist Investigates a Mass Extinction at the End of the Permian Period

by Carl Zimmer

Sam Bowring is officially a geologist at M.I.T. Unofficially, he’s a homicide detective trying to solve the ultimate cold case. Dr. Bowring wants to understand how an estimated 96 percent of all species on Earth became extinct at the end of the Permian Period 252 million years ago. It was the biggest of the five mass extinctions recorded in the fossil record. But because this killing happened so long ago, the culprit has evaded discovery for decades.

Dr. Bowring and his colleagues have now gotten an important break in the case. They’ve made the most precise measurement yet of how long it took for all those species to become extinct. Writing in the Proceedings of the National Academy of Sciences, they report that the extinction took less than about 60,000 years. That’s a geological blink of an eye — a fact that will help scientists evaluate different hypotheses for what triggered the mass extinction.

For now, however, the new result has Dr. Bowring puzzled. “I just think there’s probably something really fundamental that we don’t understand,” he said…

(read more: NY Times)

Images:

T - Skull of Dinogorgon in South Africa. Many such mammal-like species became extinct 252 million years ago. Photo by Jonathan Blair/National Geographic

B -  Fossils of extinct squidlike creatures called ammonites located in a rock layer very close to the boundary between the Permian and Triassic periods. Credit: Seth Burgess

End-Permian extinction happened in 60,000 years—much faster than earlier estimates, MIT study says The largest mass extinction in the history of animal life occurred some 252 million years ago, wiping out more than 96 percent of marine species and 70 percent of life on land—including the largest insects known to have inhabited the Earth. Multiple theories have aimed to explain the cause of what’s now known as the end-Permian extinction, including an asteroid impact, massive volcanic eruptions, or a cataclysmic cascade of environmental events. But pinpointing the cause of the extinction requires better measurements of how long the extinction period lasted.
Now researchers at MIT have determined that the end-Permian extinction occurred over 60,000 years, give or take 48,000 years—practically instantaneous, from a geologic perspective. The new timescale is based on more precise dating techniques, and indicates that the most severe extinction in history may have happened more than 10 times faster than scientists had previously thought…
(read more: PhysOrg) (Image: © John Sibbick / Natural History Museum)

End-Permian extinction happened in 60,000 years—much faster than earlier estimates, MIT study says

The largest mass extinction in the history of animal life occurred some 252 million years ago, wiping out more than 96 percent of marine species and 70 percent of life on land—including the largest insects known to have inhabited the Earth. Multiple theories have aimed to explain the cause of what’s now known as the end-Permian extinction, including an asteroid impact, massive volcanic eruptions, or a cataclysmic cascade of environmental events. But pinpointing the cause of the extinction requires better measurements of how long the extinction period lasted.

Now researchers at MIT have determined that the end-Permian extinction occurred over 60,000 years, give or take 48,000 years—practically instantaneous, from a geologic perspective. The new timescale is based on more precise dating techniques, and indicates that the most severe extinction in history may have happened more than 10 times faster than scientists had previously thought…

(read more: PhysOrg)

(Image: © John Sibbick / Natural History Museum)

Why Did Some Species Thrive When the Dinosaurs Died?
by Sid Perkins
When an asteroid or comet slammed into Earth about 66 million years ago, most of our planet’s species were wiped out in a mass extinction—including entire groups such as the nonavian dinosaurs, marine reptiles such as mosasaurs, and their flying kin the pterosaurs. But not all ecosystems suffered equally, and the dramatic difference in survival rates between marine species and freshwater ones has been particularly puzzling. A new study weighs in on the long-standing riddle.
According to some estimates, about three-quarters of the plant and animal species on Earth disappeared during the end-of-the-Cretaceous dino-killing impact. But marine ecosystems lost only about half of their species, and freshwater environments lost a mere 10% to 22%, says William Lewis, an aquatic ecologist at the University of Colorado, Boulder.
For instance, only about 10% of the major groups of bony fish died out, but species from all six groups of turtles alive at the time—and from most if not all groups of amphibians—survived the impact…
(read more: Science Now/AAAS)         
(image: Don Davis/NASA)

Why Did Some Species Thrive When the Dinosaurs Died?

by Sid Perkins

When an asteroid or comet slammed into Earth about 66 million years ago, most of our planet’s species were wiped out in a mass extinction—including entire groups such as the nonavian dinosaurs, marine reptiles such as mosasaurs, and their flying kin the pterosaurs. But not all ecosystems suffered equally, and the dramatic difference in survival rates between marine species and freshwater ones has been particularly puzzling. A new study weighs in on the long-standing riddle.

According to some estimates, about three-quarters of the plant and animal species on Earth disappeared during the end-of-the-Cretaceous dino-killing impact. But marine ecosystems lost only about half of their species, and freshwater environments lost a mere 10% to 22%, says William Lewis, an aquatic ecologist at the University of Colorado, Boulder.

For instance, only about 10% of the major groups of bony fish died out, but species from all six groups of turtles alive at the time—and from most if not all groups of amphibians—survived the impact…

(read more: Science Now/AAAS)         

(image: Don Davis/NASA)

Collision Course? A Comet Heads for Mars 
by Dr. Tony Phillips
Over the years, the spacefaring nations of Earth have sent dozens of probes and rovers to explore Mars. Today there are three active satellites circling the red planet while two rovers, Opportunity and Curiosity, wheel across the red sands below.  Mars is dry, barren, and apparently lifeless.
Soon, those assets could find themselves exploring a very different kind of world.
"There is a small but non-negligible chance that Comet 2013 A1 will strike Mars next year in October of 2014," says Don Yeomans of NASA’s Near-Earth Object Program at JPL.  "Current solutions put the odds of impact at 1 in 2000."
The nucleus of the comet is probably 1 to 3 km in diameter, and it is coming in fast, around 56 km/s (125,000 mph). “It if does hit Mars, it would deliver as much energy as 35 million megatons of TNT,” estimates Yeomans…
(read more: NASA)

Collision Course? A Comet Heads for Mars

by Dr. Tony Phillips

Over the years, the spacefaring nations of Earth have sent dozens of probes and rovers to explore Mars. Today there are three active satellites circling the red planet while two rovers, Opportunity and Curiosity, wheel across the red sands below.  Mars is dry, barren, and apparently lifeless.

Soon, those assets could find themselves exploring a very different kind of world.

"There is a small but non-negligible chance that Comet 2013 A1 will strike Mars next year in October of 2014," says Don Yeomans of NASA’s Near-Earth Object Program at JPL.  "Current solutions put the odds of impact at 1 in 2000."

The nucleus of the comet is probably 1 to 3 km in diameter, and it is coming in fast, around 56 km/s (125,000 mph). “It if does hit Mars, it would deliver as much energy as 35 million megatons of TNT,” estimates Yeomans…

(read more: NASA)

Rock that Ended Reign of the Dinosaurs Was a Comet

by Paul Rincon

The space rock that hit Earth 65 million years ago and is widely implicated in the end of the dinosaurs was likely a speeding comet.

That is the conclusion of research which suggests the 180km-wide Chicxulub crater in Mexico was carved out by a smaller object than previously thought. Many scientists consider a large and relatively slow moving asteroid to have been the likely culprit.

Details were outlined at the 44th Lunar and Planetary Science Conference.

But other researchers were more cautious about the results.

"The overall aim of our project is to better characterise the impactor that produced the crater in the Yucatan peninsula [in Mexico]," Jason Moore, from Dartmouth College in New Hampshire, told BBC News.

The space rock gave rise to a global layer of sediments enriched in the chemical element iridium, in concentrations much higher than naturally occurs; it must have come from outer space…

(read more: BBC News)                               (images: SPL)

Efforts to Protect Earth From Asteroids Are Under Way. But Will It Be Enough?
by Adam Mann
In the wake of Earth’s largest meteor strike in more than a century, the world’s attention has turned skyward.
The 17-meter bolide exploded in the air over the Chelyabinsk region of Russia on Feb. 15, shattering windows and injuring around 1,000 people. But had the meteor come in at a slightly different angle, the space rock could have impacted the ground and the fallout could have been much worse.
More money is already flowing toward future asteroid detection and mitigation strategies, but we may never be able to fully protect ourselves.
There are plenty of programs already in place for monitoring relatively large near-Earth objects, and more will be coming online soon, both from government space agencies and the private sector. However, even the best efforts will not be able to catch objects the size of the Chelyabinsk meteor — rocks that are small enough to evade detection by current technology until they are streaking through Earth’s atmosphere, but large enough to be dangerous…
(read more: Wired Science)        

Efforts to Protect Earth From Asteroids Are Under Way. But Will It Be Enough?

by Adam Mann

In the wake of Earth’s largest meteor strike in more than a century, the world’s attention has turned skyward.

The 17-meter bolide exploded in the air over the Chelyabinsk region of Russia on Feb. 15, shattering windows and injuring around 1,000 people. But had the meteor come in at a slightly different angle, the space rock could have impacted the ground and the fallout could have been much worse.

More money is already flowing toward future asteroid detection and mitigation strategies, but we may never be able to fully protect ourselves.

There are plenty of programs already in place for monitoring relatively large near-Earth objects, and more will be coming online soon, both from government space agencies and the private sector. However, even the best efforts will not be able to catch objects the size of the Chelyabinsk meteor — rocks that are small enough to evade detection by current technology until they are streaking through Earth’s atmosphere, but large enough to be dangerous…

(read more: Wired Science)        

Chicxulub Crater
Asteroid impact date: Estimated 65 million years ago
Location: Yucatán, Mexico
Specs: Located on the Yucatán Peninsula in Mexico, many scientists believe that the meteorite that left this crater caused or contributed to the extinction of the dinosaurs. Estimates of its actual diameter range from 106 to a whooping 186 miles (170 to 300 kilometers), which if proved right could mean it’s the biggest…
(learn more about impact craters: National Geographic)
(image: Detlev van Ravenswaay, Science Source)

Chicxulub Crater

Asteroid impact date: Estimated 65 million years ago

Location: Yucatán, Mexico

Specs: Located on the Yucatán Peninsula in Mexico, many scientists believe that the meteorite that left this crater caused or contributed to the extinction of the dinosaurs. Estimates of its actual diameter range from 106 to a whooping 186 miles (170 to 300 kilometers), which if proved right could mean it’s the biggest…

(learn more about impact craters: National Geographic)

(image: Detlev van Ravenswaay, Science Source)

Asteroid Impact That Killed the Dinosaurs: New Evidence

by Charles Choi

The idea that a cosmic impact ended the age of dinosaurs in what is now Mexico now has fresh new support, researchers say.

The most recent and most familiar mass extinction is the one that finished the reign of the dinosaurs — the end-Cretaceous or Cretaceous-Tertiary extinction event, often known as K-T. The only survivors among the dinosaurs are the birds.

Currently, the main suspect behind this catastrophe is a cosmic impact from an asteroid or comet, an idea first proposed by physicist Luis Alvarez and his son geologist Walter Alvarez. Scientists later found that signs of this collision seemed evident near the town of Chicxulub (CHEEK-sheh-loob) in Mexico in the form of a gargantuan crater more than 110 miles (180 kilometers) wide. The explosion, likely caused by an object about 6 miles (10 km) across, would have released as much energy as 100 trillion tons of TNT, more than a billion times more than the atom bombs that destroyed Hiroshima and Nagasaki…

(read more: Live Science)              

(images: Illustration by Don Davis; photo by Paule Renne)

Discovery: Earth’s Oldest Crater Is Largest Too
by Douglas Main
A study of Greenland’s rocks may have turned up something unexpected: the oldest and largest meteorite crater ever found on Earth.
Researchers think the crater was formed 3 billion years ago, making it the oldest ever found, said Danish researcher Adam Garde. The impact crater currently measures about 62 miles (100 kilometers) from one side to another. But before it eroded, it was likely more than 310 miles (500 km) wide, which would make it the biggest on Earth, Garde told OurAmazingPlanet.
The team has calculated it was caused by a meteorite 19 miles (30 km) wide, which, if it hit Earth today, would wipe out all higher life…
(read more: OurAmazingPlanet)      (image: Carsten Egestal Thuesen, GEUS)

Discovery: Earth’s Oldest Crater Is Largest Too

by Douglas Main

A study of Greenland’s rocks may have turned up something unexpected: the oldest and largest meteorite crater ever found on Earth.

Researchers think the crater was formed 3 billion years ago, making it the oldest ever found, said Danish researcher Adam Garde. The impact crater currently measures about 62 miles (100 kilometers) from one side to another. But before it eroded, it was likely more than 310 miles (500 km) wide, which would make it the biggest on Earth, Garde told OurAmazingPlanet.

The team has calculated it was caused by a meteorite 19 miles (30 km) wide, which, if it hit Earth today, would wipe out all higher life…

(read more: OurAmazingPlanet)      (image: Carsten Egestal Thuesen, GEUS)

Better Collision Insurance:  
Asteroids smaller than those now being actively catalogued constitute a largely neglected natural hazard 
by Russell Schweickart, Clark Chapman
In October 2001, we and 22 like-minded engineers and astronomers, including a few former and current astronauts, got together at the Johnson Space Center in Houston to discuss what we saw as a missing element in the space program: attention to the possibility of our planet being struck by a near-Earth asteroid. We knew of the accelerating rate at which such objects were being discovered. But no one, certainly no federal or international agency, was taking seriously the question of what exactly to do when an asteroid is found with our address on it.
During that initial meeting, less than six weeks after the 9/11 terrorist strike, we decided that this threat from outer space needed to be dealt with seriously and that our group might just be able to move the process along. To facilitate our work, we formed the B612 Foundation, a non-profit corporation named after the home asteroid of the title character in Antoine de Saint-Exupéry’s The Little Prince.
NASA has been spending about $4 million a year to meet a 1998 Congressional mandate to chart (by 2008) at least 90 percent of the near-Earth asteroids that are more than 1 kilometer in diameter. NASA’s Jet Propulsion Laboratory has been overseeing the effort, called the Spaceguard Survey, which has to date discovered more than 790 of an estimated 1,100 or so of these huge, rocky objects. The impact of a 1-kilometer asteroid would release the same amount of energy as 70,000 megatons of TNT or, equivalently, as 1,400 of the largest thermonuclear weapons ever detonated. The subsequent Sun-dimming pall of debris lofted high into the atmosphere would envelop our planet for months, threatening all of human civilization…
(read more: American Scientist)     (image: Russell House)

Better Collision Insurance: 

Asteroids smaller than those now being actively catalogued constitute a largely neglected natural hazard 

by Russell Schweickart, Clark Chapman

In October 2001, we and 22 like-minded engineers and astronomers, including a few former and current astronauts, got together at the Johnson Space Center in Houston to discuss what we saw as a missing element in the space program: attention to the possibility of our planet being struck by a near-Earth asteroid. We knew of the accelerating rate at which such objects were being discovered. But no one, certainly no federal or international agency, was taking seriously the question of what exactly to do when an asteroid is found with our address on it.

During that initial meeting, less than six weeks after the 9/11 terrorist strike, we decided that this threat from outer space needed to be dealt with seriously and that our group might just be able to move the process along. To facilitate our work, we formed the B612 Foundation, a non-profit corporation named after the home asteroid of the title character in Antoine de Saint-Exupéry’s The Little Prince.

NASA has been spending about $4 million a year to meet a 1998 Congressional mandate to chart (by 2008) at least 90 percent of the near-Earth asteroids that are more than 1 kilometer in diameter. NASA’s Jet Propulsion Laboratory has been overseeing the effort, called the Spaceguard Survey, which has to date discovered more than 790 of an estimated 1,100 or so of these huge, rocky objects. The impact of a 1-kilometer asteroid would release the same amount of energy as 70,000 megatons of TNT or, equivalently, as 1,400 of the largest thermonuclear weapons ever detonated. The subsequent Sun-dimming pall of debris lofted high into the atmosphere would envelop our planet for months, threatening all of human civilization…

(read more: American Scientist)     (image: Russell House)

Discovery:  Earth’s Oldest Crater Is Also Its Largest
by Douglas Main
A study of Greenland’s rocks may have turned up something unexpected: the oldest and largest meteorite crater ever found on Earth.
Researchers think the crater was formed 3 billion years ago, making it the oldest ever found, said Danish researcher Adam Garde. The impact crater currently measures about 62 miles (100 kilometers) from one side to another. But before it eroded, it was likely more than 310 miles (500 km) wide, which would make it the biggest on Earth, Garde told OurAmazingPlanet.
The team has calculated it was caused by a meteorite 19 miles (30 km) wide, which, if it hit Earth today, would wipe out all higher life…
(read more: OurAmazingPlanet)       (image: Carsten Egestal Thuesen, GEUS)

Discovery:  Earth’s Oldest Crater Is Also Its Largest

by Douglas Main

A study of Greenland’s rocks may have turned up something unexpected: the oldest and largest meteorite crater ever found on Earth.

Researchers think the crater was formed 3 billion years ago, making it the oldest ever found, said Danish researcher Adam Garde. The impact crater currently measures about 62 miles (100 kilometers) from one side to another. But before it eroded, it was likely more than 310 miles (500 km) wide, which would make it the biggest on Earth, Garde told OurAmazingPlanet.

The team has calculated it was caused by a meteorite 19 miles (30 km) wide, which, if it hit Earth today, would wipe out all higher life…

(read more: OurAmazingPlanet)       (image: Carsten Egestal Thuesen, GEUS)