Study suggests dinosaurs killed off by more than one asteroid

Aug 31, 2010 by Lin Edwards report
Image credit: NASA.

(PhysOrg.com) -- Dinosaurs, along with over half of other species, became extinct at the end of the Cretaceous period about 65.5 million years ago, and many scientists believe this was due to a single impact with an asteroid that hit at Chicxulub in the Gulf of Mexico. Now a study published in the Geology journal proposes the impact that produced the Boltysh crater in the Ukraine may also have been involved in the extinctions, and there may have been a shower of asteroids or comets.

Professor David Jolley of Aberdeen University in Scotland, and Professor Simon Kelley of the Open University, led a team studying the Boltysh , which was discovered in 2002. The Boltysh crater is only 24 kilometers in diameter and therefore much smaller than the Chicxulub at over 180 km across.

The team studied fossilized plant pollen and spores found in the mud that filled the Boltysh crater, and found that ferns colonised the area soon after the impact, but there was another colonisation a meter above the first, suggesting a second asteroid impact had occurred elsewhere causing repeat devastation. The researchers attributed this second spike, which occurred two to five thousand years later, to the aftermath of the Chicxulub impact.

Ferns are known to colonise devastated areas rapidly after disasters, so layers of fern spores known as "fern spikes" are considered to be good indicators of impact events in the past.

The theory that an asteroid impact caused the of the dinosaurs and other species was first put forward in 1980, at which time it created a great deal of controversy until the crater at Chicxulub was discovered and dated to 65 million years ago.

Other theories for the mass extinctions include enormous volcanic eruptions of the Deccan Traps in India about the same period that would have spewed toxic gases into the atmosphere. There is also a theory the triggered global earthquakes that in turn caused the Deccan Traps eruptions.

Professor Kelley said it is possible evidence will be found in future for more impact events around the same time, suggesting dinosaurs and many other species may have been wiped out due to the effects of an asteroid shower lasting thousands of years.

Explore further: Wastewater injection is culprit for most quakes in southern Colorado and northern New Mexico

More information: Two large meteorite impacts at the Cretaceous-Paleogene boundary, David Jolley et al., Geology, v. 38 no. 9 p. 835-838. doi:10.1130/G31034.1

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kevinrtrs
1 / 5 (18) Aug 31, 2010
There is of course an alternate theory that a global flood caused massive ecological changes, resulting in the one true ice-age which was the final nail in the coffin of the dinosaurs struggling to survive on food that was no longer adequate to sustain their bodies.

Having an asteroid impact theory for the extinction of dinosaurs is one thing. Proving it is another matter altogether. Then there's the question of whether dinosaurs really became extinct 65m years ago. How on earth can this be shown to be true? There are just too many variables to cover and massive simplifying assumptions have to be made.
Just stating that it's an accepted fact does not make it so.
Evolutionary scientists have established a very fool-proof method to prevent any controversy from arising with regards to the age of dinosaurs - they've effectively prohibited anyone from doing double or triple blind C14 measurements on dinosaur bones, pretending that C14 dating doesn't work for that ASSUMED age!!Go Figure!
Skeptic_Heretic
5 / 5 (17) Aug 31, 2010
There is of course an alternate theory that a global flood
No, that would be a hypothesis, and a bad one at that.
Having an asteroid impact theory for the extinction of dinosaurs is one thing. Proving it is another matter altogether.
Except we have evidence for an impactor and no evidence of a flood.
Then there's the question of whether dinosaurs really became extinct 65m years ago. How on earth can this be shown to be true?
Radiometric dating.
There are just too many variables to cover and massive simplifying assumptions have to be made.
The only simplification is in attempting to convey the results to an ignoramus like yourself.
Just stating that it's an accepted fact does not make it so.
No, the half century of peer reviewed research does that.
they've effectively prohibited anyone from doing double or triple blind C14
No they haven't. C14 dating wouldn't work as the fossils are too old. Are you really this stupid?
Skeptic_Heretic
5 / 5 (12) Aug 31, 2010
You know, Kev, I shouldn't call you stupid, but you've been told that you're wrong, and had evidence supplied literally hundreds of times if not thousands over the course of your life. Sticking your head in the sand because of some unsupportable method of faith is ridiculous. Almost all of medical science, biology, ecology, and all the other fields that make our lives livable are based on fundamental tenets that you dismiss offhand. If you really don't think any of this happened, go join a religious retreat where you'll never be botherd by medicine, electricity, safe foods, current construction, or machine based tools ever again. After a few months of living like a turn of the century farmer you will probably change your tune mighty fast.

Evolution doesn't disprove your faith or your god. You're quite welcome to have your religious outlook and beliefs within the framework of evolution, abiogenesis, and just about everything else current within science. Take a lesson from Aquinas.
LKD
1 / 5 (2) Aug 31, 2010
Wasn't there a recent article that there is no clear evidence that a meteor hit caused any globe wide alteration of the environment?

http://www.physor...871.html
http://www.physor...449.html

What am I to believe here?
Skeptic_Heretic
4.6 / 5 (5) Aug 31, 2010
Wasn't there a recent article that there is no clear evidence that a meteor hit caused any globe wide alteration of the environment?

http://www.physor...871.html

What am I to believe here?

That article you link is a corrolary hypothesis that the Deccan traps caused the extinction due to the perceived biodiversity and lack of extinction of common species in the area of the Chixulub impact. I'm of mind that it was a combination: a great impact caused massive earthquakes and resulted in the Deccan Traps, which lead to climate change and die off of larger species. In that hypothesis the impact is needed, and is an indirect cause as opposed to a direct cause.
LKD
Aug 31, 2010
This comment has been removed by a moderator.
daveinqueens
3.8 / 5 (5) Aug 31, 2010
i'm convinced the deccan traps were an antipodal response to the chixulub impact.
Skeptic_Heretic
5 / 5 (3) Aug 31, 2010
i'm convinced the deccan traps were an antipodal response to the chixulub impact.

I'm not sure they line up appropriately. With continental drift you're off by about a thousand miles or so.

Now, if there was another impact that was antipodal to the Deccan traps it would be gone by now. The impact would have occured in the eastern equatorial pacific ocean. Since the sea floor is refreshed rather vigorously over time that impact crater would most likely be long gone by now.

The interesting thing about the Chixulub impact is the quantity of sulphur in the area. That sulphur would have been vaporized creating thick clouds of acid rain for several decades. Perhaps there were multiple asteroid or meteor strikes, or a rubble pile asteroid broke up into several pieces as it passed through the solar system to rain pain upon the planet. Also, don't discount the fact that if the impactor was sufficiently large it could have filled in its own crater (unlikely).
daveinqueens
4 / 5 (2) Aug 31, 2010
i suggest that the deccan traps may have had an unusually thin crust and the reverberation caused by the chixulub impact was enough to set off the eruptions. the seismic wave caused by an impact as large as chixulub is believed to be surely could have caused a rupture; 1000 miles seems like a pretty short distance to the antipode.
Skeptic_Heretic
4 / 5 (1) Aug 31, 2010
i suggest that the deccan traps may have had an unusually thin crust and the reverberation caused by the chixulub impact was enough to set off the eruptions. the seismic wave caused by an impact as large as chixulub is believed to be surely could have caused a rupture; 1000 miles seems like a pretty short distance to the antipode.
Would have to have been an antipodal earthquake registering well over the Richter scale to cause the deccan traps. Secondly, the true antipode would have been even more greatly affected if that was the case.
daveinqueens
3 / 5 (1) Aug 31, 2010
don't have a globe handy, what is the approx position of the antipode of the deccan traps taking continental drift into account?
Shootist
4.3 / 5 (6) Aug 31, 2010
Whole lotta nonsense here today.

The K/T boundary is buried under the Deccan Traps. The Deccan Traps happened after Chicxulub.

The age dating of Boltish crater is within the standard error of measurement. It is possible that the crater formed concurrently with Chicxulub. It is possible it occurred +-500Ky, as well.

There are seismic studies of Chicxulub which posits a second crater some 100km in diameter, immediately adjacent to, and NE of Chicxulub crater. Why this isn't mentioned in the article, I cannot say.

As for antipodal affects? None of the bolides in question are large enough to produce igneous events on the other side of the planet. Astrophysicists even question whether 50km bolides traveling at 25km/sec are sufficient to produce these events on Mars (Utopia Basin, Hellas Basin) or the Moon (SP Aiken). The question remains unanswered.

Skeptic_Heretic
4 / 5 (2) Aug 31, 2010
The K/T boundary is buried under the Deccan Traps. The Deccan Traps happened after Chicxulub.
Well you'd kind of expect that if it was an antipodal impact event. How far underneathe is the KT boundary by geologic timescale?
Shootist
2.5 / 5 (2) Aug 31, 2010
Right underneath. The traps are a result of the Indian Plate diving under the Tibetan plateau.

I cannot attest to the complete accuracy of the following, but it gives, what I understand to be, a low resolution estimate of the continental plates position 65Mya.

http://www.enchan...ft.shtml

Shootist
3.8 / 5 (4) Aug 31, 2010
When talking about potential geologic effects of impacts it is good to have sometime to compare against. There are numerous medium sized impacts (300-500km), on bodies much smaller than Earth, that have no discernible antipodal.

Tharsis, on Mars, is often cited as evidence of antipodal activity, but Tharsis is 500My to 1Gy younger than Utopia (3300km) or Hellas (2300km) Basins (neither of which is actually antipodal, anyway)

South Pole Aitken Basin (a 2500km basin on a body 3476km in diameter!) does not exhibit antipodal effect.

The only real physical evidence of antopodal effects, in a Terrestrial planet, is the Caloris Basin (1300km) impact on Mercury. There is a large area of Chaos Terrain at its antipode.
Skeptic_Heretic
4.7 / 5 (3) Aug 31, 2010
Right underneath. The traps are a result of the Indian Plate diving under the Tibetan plateau.

I cannot attest to the complete accuracy of the following, but it gives, what I understand to be, a low resolution estimate of the continental plates position 65Mya.

http://www.enchan...ft.shtml


Couple of problems with that statement. The Deccan Traps are in the southern and central parts of the continenet for the most part. Therre are no instances (that I'm aware of) where a basalt plain has been created by simple subduction, especially over such a wide area and so far away from the fault line. Secondly, from the few articles I dug up it appears the deccan traps aren't right above the KT boundary but they intersect the KT boundary. Lending further creedence to the two events being relatively contemporary to one another geologically speaking.
marjon
2.3 / 5 (7) Aug 31, 2010
There seems to be a real data to support the effects of asteroid impacts on the earth.
What real effort is underway to ensure this will not occur again?
aennen
4 / 5 (1) Aug 31, 2010
Wasnt the actual extinction process 10's to 100's of thousands of year, not in year.
Shootist
3.7 / 5 (3) Aug 31, 2010
Therre are no instances (that I'm aware of) where a basalt plain has been created by simple subduction, especially over such a wide area and so far away from the fault line. Secondly, from the few articles I dug up it appears the deccan traps aren't right above the KT boundary but they intersect the KT boundary. Lending further creedence to the two events being relatively contemporary to one another geologically speaking.


You are correct on the intersection. The Indian plate began colliding about 71My and eruptions were continually occurring along the fault. This, long before the Thetys sea closed, which didn't occur until 50Mya.

There are three large Igneous provinces in the Western US directly attributed to the subduction of the pacific plate under the continental plate. Not as large, perhaps, as the Deccan or Siberian, but the largest Caldera in existence, bisected by the Grand Canyon, is one of 50 large Calderas spread across New Mexico, Utah, Arizona and Colorado.
Skeptic_Heretic
not rated yet Aug 31, 2010
There are three large Igneous provinces in the Western US directly attributed to the subduction of the pacific plate under the continental plate. Not as large, perhaps, as the Deccan or Siberian, but the largest Caldera in existence, bisected by the Grand Canyon, is one of 50 large Calderas spread across New Mexico, Utah, Arizona and Colorado.
I think you need to look at a map of the fault lines. Calderas are also not equatable to subduction in most cases.

The fault line runs along the northern border of India, the deccan traps are rather far south of the primary subduction zone, in addition to this, the traps would be on the wrong side of the fault if subduction was at play.
jsa09
5 / 5 (7) Sep 01, 2010
@kevinrtrs

Your comment was disected and responded to above. But some parts were left unanswered, and I don't want you to think that was because you might be right.

There is of course an alternate theory that a global flood caused massive ecological changes, resulting in the one true ice-age which was the final nail in the coffin of the dinosaurs


The ice ages have been measured in the archeological record. They do not correspond to the extinction event and no one can figure out how to get an ice age from a flood anyway.

struggling to survive on food that was no longer adequate to sustain their bodies.


The old thinking that dinosaurs grew too big to eat has been shown to be complete myth. It is rubbish thinking. It has been shown through studies of island communities where large animals are too big to survive happily, that they evolve to be smaller.

ssco00
5 / 5 (4) Sep 04, 2010
"Evolutionary scientists have established a very fool-proof method to prevent any controversy from arising with regards to the age of dinosaurs - they've effectively prohibited anyone from doing double or triple blind C14 measurements on dinosaur bones, pretending that C14 dating doesn't work for that ASSUMED age!!Go Figure!"

There are no dinosaur bones, only fossils. The organic material in the original bones, which contained the C14, was long ago replaced with mineral material which has no C14 to test. Also, after about 10 half-lives of decay, about 50,000 years for C14, results are not very useful.

The ages offered are not assumed, but calculated from the rock matrix in which the fossils are found. No one can be prohibited from experimenting on C14, but that would not be involved with dinosaur fossils in any case. It would be well to begin with actual facts, not fanciful, wishful thinking.
Shootist
1 / 5 (1) Sep 05, 2010
The fault line runs along the northern border of India, the deccan traps are rather far south of the primary subduction zone, in addition to this, the traps would be on the wrong side of the fault if subduction was at play.


The Igneous provinces in NA are 1400km from the fault.

The Traps may have been caused by, India's subduction under the Tibetan plateau, due to crustal heating.

http://www.nature....87.html
Skeptic_Heretic
not rated yet Sep 05, 2010
The igneous provinces in NA are on the correct side of the fault. The igneous provinces would be on the side that is on top, not on the bottom.

India is being subducted under the Asiatic plate. The igneous provinces should be in southern China.

And there it is.
eachus
5 / 5 (1) Sep 06, 2010
The Traps may have been caused by, India's subduction under the Tibetan plateau, due to crustal heating.

It is interesting how two arguments against the Chicxulub impact causing the Deccan traps work together to provide an explanation.

At the time of the Chicxulub impact, the antipodes would have corresponded to the leading edge of the Indian plate subducting under Asia. The seismic waves from the impact would have caused this edge of the plate to move upward. That would have fractured the ninge in the plate, already under stress, and would have concentrated the pressure wave energy over the subducting area of the plate into the area of the hinge. (Note that this area has one vertical dimension.)

To top it off, what happens if the hinge snaps, as it likely would have? You now get a Ricter 10 or so earthquake as the new edge of the Indian plate snaps upward free from the drag of the subducting part of the plate. ;-)

It would be interesting to try a good 3-d simulation.