© NASA/Donald E. DavisAn artist's impression of a giant space rock slamming into Earth 65 million years ago near what is now Mexico's Yucatan Peninsula. A consortium of scientists now says this was indeed what caused the end of the Age of Dinosaurs.
Asteroids aren't completely random?Mass extinctions of life on Earth appear to follow a regular pattern, a
new study suggests.
In fact, widespread die-offs of land-dwelling animals - which include amphibians, reptiles, mammals and birds - follow a cycle of about 27 million years, the study reports. The study also said these mass extinctions coincide with major asteroid impacts and devastating volcanic outpourings of lava.
"The global mass extinctions were apparently caused by the largest cataclysmic impacts and massive volcanism, perhaps sometimes working in concert," said study lead author Michael Rampino of New York University, in a
statement.
Paleontologists had previously discovered that similar mass extinctions of marine life, in which up to 90% of species disappeared, were not random events, but seemed to come in a 26-million-year cycle.
How could this be? Aren't asteroid or comet impacts completely random? Apparently not, the study suggests, and it's because of the orbit of our planet through the galaxy.
The solar system passes through the crowded part of our Milky Way galaxy about every 30 million years. During those times, comet showers are possible, leading to large impacts on the Earth.
© Michael R. Rampino , Ken Caldeira & Yuhong ZhuFigure 3. Power spectrum of the ages of 10 extinction episodes of non-marine tetrapods of the past 290 My (Table 1) based on the Fourier transform analysis (Gasquet and Witomski 1999). The most significant peak (≥99% confidence) occurs at a period of 27.5 My
"These new findings of coinciding, sudden mass extinctions on land and in the oceans, and of the common 26- to 27-million-year cycle, lend credence to the idea of periodic global catastrophic events as the triggers for the extinctions," Rampino said.
"In fact, three of the mass annihilations of species on land and in the sea are already known to have occurred at the same times as the three largest impacts of the last 250 million years, each capable of causing a global disaster and resulting mass extinctions."
© The Conversation, CC BY-ND
The study said that the impacts can create conditions that would stress and potentially kill off land and marine life, including widespread dark and cold, wildfires, acid rain and ozone depletion. The most infamous asteroid strike we know of is the one that killed off the dinosaurs some 66 million years ago, which overall wiped out 70% of the species on Earth.
"It seems that large-body impacts and the pulses of internal Earth activity that create flood-basalt volcanism may be marching to the same 27-million-year drumbeat as the extinctions, perhaps paced by our orbit in the galaxy," Rampino said.
And as for where we are in the current cycle, he told
USA TODAY that we're about 20 million years away from the next predicted mass extinction that's due to a comet strike or volcanic activity.
The study was published Friday in the journal
Historical Biology.
Reader Comments
The solar system takes about 250 million years to circuit the galaxy once. How is that 30 million year cycle coming about ? Comet heaps in regular distances, or what ? Those celestrial bodies fall victim to Occam's Razor.
You don't need impacts for mass extinctions. A solar micro nova suffices.
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And his assertion to know which side of the earth will be hit (implying knowledge of the exact date and time) is ... quite bold.
But his claim of knowing the exact date and time is IMHO without substance.
R.C.
also, thinking out loud here, seven cycles… seven harmonics…hmmm, i’ve got these puzzle pieces in front of me, just trying to put them together, anyone...anyone, bueller ?
I agree his prediction is a bit absurd.
...here we go;
Ice Age: Collision Course - Wikipedia
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i'll give you a siskel and ebert two thumbs up for the link tho