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An artist's impression of a 6-mile-wide asteroid striking the Earth. Scientists now have fresh evidence that such a cosmic impact ended the age of dinosaurs near what is now the town of Chixculub in Mexico.
By Charles Choi
LiveScience
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 kilometers) 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.
However, further work suggested the Chicxulub impact occurred either 300,000 years before or 180,000 years after the end-Cretaceous mass extinction. As such, researchers have explored other possibilities, including other impact sites, such as the controversial Shiva crater in India, or even massive volcanic eruptions, such as those creating the Deccan Flats in India.
Courtesy of Paul Renne
Doctoral student Bill Mitchell collects a volcanic ash sample from a coal bed just above the final dinosaur extinction level.
Timing of an impact
New findings using high-precision radiometric dating analysis of debris kicked up by the impact now suggest the K-T event and the Chicxulub collision happened no more than 33,000 years apart. In radiometric dating, scientists estimate the ages of samples based on the relative proportions of specific radioactive materials within them. [Wipe Out: History's Most Mysterious Mass Extinctions]
"We've shown the impact and the mass extinction coincided as much as one can possibly demonstrate with existing dating techniques," researcher Paul Renne, a geochronologist and director of the Berkeley Geochronology Center in California, told LiveScience.
Courtesy of Klaudia Kuiper
Near Jordan, Mont., rock layers expose the level (lower arrow) where dinosaurs and many other animals and plants went extinct. The arrows point to coal beds that contain thin volcanic ash layers that were dated.
"It's gratifying to see these results, for those of us who've been arguing a long time that there was an impact at the time of this mass extinction," geologist Walter Alvarez at the University of California at Berkeley, who did not participate in this study, told LiveScience. "This research is just a tour de force, a demonstration of really skillful geochronology to resolve time that well."
The fact the impact and mass extinction may have been virtually simultaneous in time supports the idea that the cosmic impact dealt the age of dinosaurs its deathblow.
"The impact was clearly the final straw that pushed Earth past the tipping point," Renne said. "We have shown that these events are synchronous to within a gnat's eyebrow, and therefore, the impact clearly played a major role in extinctions, but it probably wasn't just the impact."
The new extinction date is precise to within 11,000 years.
"When I got started in the field, the error bars on these events were plus or minus a million years," added paleontologist William Clemens at the University of California at Berkeley, who did not participate in this research. "It's an exciting time right now, a lot of which we can attribute to the work that Paul and his colleagues are doing in refining the precision of the time scale with which we work."
Cosmic Log: Asteroid closes in for close encounter — and a swift kick
Although the cosmic impact and mass extinction coincided in time, Renne cautioned this does not mean the impact was the only cause of the die-offs. For instance, dramatic climate swings in the preceding million years, including long cold snaps in the general hothouse environment of the Cretaceous, probably brought many creatures to the brink of extinction. The volcanic eruptions behind the Deccan Traps might be one cause of these climate variations.
"These precursory phenomena made the global ecosystem much more sensitive to even relatively small triggers, so that what otherwise might have been a fairly minor effect shifted the ecosystem into a new state," Renne said.
The cosmic impact then proved the death blow.
"What we really need to do is to understand better what was going on before the impact — what was the level of ecological stress that existed that allowed the impact to be the straw that broke the camel's back?" Renne said. "We also need better dates for the massive volcanism at the Deccan Flats to better understand when it first started and how fast it occurred."
The scientists will detail their findings in Friday's issue of the journal Science.
Follow LiveScience on Twitter @livescience. We're also on Facebook and Google+.
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Leave a Comment:
It was Obamacare...I swear!!!!
Again, it is very funny how "man" wants to make up reasons or ideas!
Sorry "evolutionist" - You are so very wrong! You are the "biggest looser"!You can't make "man" with your failed model! You lost! If you truely believe ths evolution crap... show me your smarts! You cannot! You cannot show ANY facts or ideas to support your silly ideas! None!
!
God made this - and if you don't like it, tell Him... Not me!
I had a chat with God. Turns out, he gave most of us the ability to reason with the expectation that we use the gift of intellect. Like everything else though, he blessed us by adding in something by which to compare so that we would appreciate that gift. Please do not worry that you were one of those chosen to help us appreciate gifted minds, he loves you just the same. This will be difficult to grasp, I am sure. Just keep your faith and all will be well. Trust in God and in the rest of us. Please.
People who chat with "god" are normally not considered sane. As Hermoine said in a Harry Potter movie: "No, Harry. Even in the wizarding world hearing voices isn't a good sign." However, I do not believe that arbyuu truly had a chat with God. Rather it is Kem who is illogical or crazy because he/she has resorted to insults and extremes. For example words which are insults such as, "wrong, looser, failed, crap, smarts, and silly", have no place in a logical debate. They are instead and example of a vapid and empty mind. In biology, evolution is a settled issue. It is the unifying theory of life. Everyone should celebrate this February 12th!, Darwin's birthday.
"Absence of proof is not proof of absence..." Darwin was a brilliant man who made many observations and had a brilliant insight into a theory that explained his observations. Now we need "proof" which is a little higher threshold. Consensus is self-enforced orthodoxy, not proof.
OBTW, If you have Newcastle or Boddington's Pale Ale, I'll celebrate Darwin's B-day with you.
DaveyJones
DaveyJones, I don't have those beers. I normally drink either Harp or Michelob Lager. However, I do have a can of Dales Pale Ale that some friends gave me. It's not bad. At least it seems we can agree on something. :-)
Because your mind is closed Kem.
"Awwww.... I belive in Evolution! Shoutit! Im too stupid to believe enythin elses! Evolution must be smart cause I gotz no other brains to thinor stoody ak bout eny thing els. I must be right cause all us dumb donkeys believe in it there. Gotsta be a fect! Y the heck wood I wanna think (THINK) or stoodie enythig else. Me gonna take evolusion line, hook, and stinker... cauas i mite be two stuped to think of belive sompin else!
Very interesting.
HarHarHar
"evolution"
No facts, no science, no history!
Your religion of evolution cannot back-up ANY claims!
Soopid! Illiterate! Lacks Intelligence!
HarHarHar
You may be just trolling, but I still like to point out to the sane listeners that the evidence for evolution includes basically all biological science research ever done in the last 150 years, all of which fits evolutionary theory, and not one fact ever discovered refutes it.
But carry on embarrassing yourself with your ignorance.
Show me science! Show me repeatable or replicable experimennts! Oh... you can't? How about fossil records? Oh, they aren't there? Welp, believe it all you want - but dont tell me your "religon" is smarter than mine....
I tried that. It didn't work.
Would you try to hold a conversation with a dog that does nothing but bark angrily at you?
I mean, you'd feel pretty silly for trying in the first place, but eventually you just have to give up because it does nothing but bark. It's useless.
And yeah, I do believe that my "religion" of science is smarter than yours. You sure do like to demand evidence (and then ignore it), but what does YOUR religion have to offer in the way of scientifically valid origins of mankind?
KEM aka DF. Here is something you should read but I know you're too deluded to attempt it. http://evolution.berkeley.edu/evolibrary/misconceptions_faq.php#e1
Where is the proof of your religion?
Funny how all the "evolutionist" shut up an went to bed! No answers from them! Believe a false religon and go to sleep....
Sometimes humans sleep at night. Get out of attack mode occasionally.
Or maybe they just stopped paying attention to the rabid troll.
is it possible the meteor impact and following shockwave caused multiple volcano eruptions thus clouding the atmosphere and killing all plants and starving the dinosaurs?
The impact itself would probably cloud the atmosphere enough to do that, but yes, it is possible it also triggered volcanoes.
There were also extensive worldwide forest fires. This would have polluted the air for years. The layer of rock just above the iridium anomaly, which is normally considered the K-T boundary, contains a fern spike. One third of the higher level plant taxa went extinct and for a short time ferns became the dominant plant group. Today, ferns often colonize areas damaged by forest fires. (link)
look at the way we bicker. war after war. The "believers" seem to be among the worst! Seriously, how many people have been killed "in the name of God"? Do you think that maybe, if there is a God, She created us for her eternal entertainment?
Atheism has a pretty impressive record in "killing fields" if you're a student of history. Pol Pot was merely one of the more recent Marxist Murderers, with over a MILLION of his own people killed.
Stalin killed 20-25 MILLION Russians.
MAO killed 60-85 MILLION Chinese.
Che was a mere pipsqueak, having only killed 102,000 of his own people, with another HALF MILLION exiled to re-education camps where they either DIED or became Politically Correct.
Maybe that's why BHO's communications director called MAO (60-85 MILLION dead) her "favorite political philosopher..."
Yep, Atheism is definitely "the religion of peace!"
oh gosh, I'm not saying there is any difference in the bad behavior of "believers" versus atheists. I said, "believers seem to be among the worst". Most Christians believe God created us all, and that God is all loving. Yet, Christians seem to be quick to condemn others. Are Christians any worse? Probably not, but they sure as hell ain't no better than the rest of mankind. Argue that, pilgrim. I would further argue that if one does believe there is one, "all knowing", "all loving" God, and that God created the universe and all of mankind, and gave mankind the ability to reason, that the beliefs (or non belief) of all men and women are part of "God's plan" and are all equally valid. Who is a man to judge that one belief is more true than another? If you believe in God, shouldn't you also accept that there is goodness in the men of many faiths? On the other hand, the ability to wage war and to inflict pain seems to be part of the human condition, crossing all lines of faith and reason.
Davey, you need to distinguish between the religious cults of personality (Stalin, Pol Pot, Hitler, Mao) and actual Atheists. Strong beliefs can result in people flying planes into buildings or people writing awesome music. Atheism is not a religion anymore than a vacuum is a gas. In any case, the story in question was about the extinction of non-avian dinosaurs. I doubt if any of those creatures were religious. They just happened to be alive at the same time that the Deccan Traps were erupting and a 6 mile in diameter asteroid hit the earth. Wham, bang, and only the turtles did well. ;-)
If dinosuars were buried in sediments then I would believe in a big flood, otherwise, I think this asteroid thing really holds water.
Those who believe in Creation as depicted in Genesis, are quick to point out that "everything must have a cause; everything you see was created by someone." Then you are forced to ask, "what created God?" Then we have to accept the possibility that SOMETHING exists that was not created. And if that, why can't the universe not have a cause? If God can have no cause, so can the universe.
There are hundreds of differing Christian sects and denominations. The Christians who oppose the findings of science are fundamentalist Christians, also generally known as "Bible literalists." They're the one's who somehow believe that God wrote the Bible...or inspired the anonymous authors who did. The trouble with the latter, however, is that anyone can babble nonsense and say it was "inspired by God." Anyone.
I've always wondered why super religious people come into the science section and read these articles. Why? You know it's just going to upset you. You either have scientific standards or you don't so why even bother? You honestly think you are going to convert anyone with your fairy tales?
You are free to read and comment on whatever you like but i'm just speaking from a point of curiosity here because it makes no sense to me. Clearly if you don't value science and hold no scientific standard then you probably shouldn't be reading scientific articles. Just saying....
I knew when I saw the topic that I was in for a treat ! I was not disappointed. Thanks to all you BELIEVERS for a hilarious read ! I am now going to do some work. Egad !
A double, or even a triple "whammy" is probably what it took to clean dinosaurs off our planet so thoroughly. - RC
Religious people read articles like this because they can be curious as well. Everyone talks about there being no proof of Creation yet all the "proof" I have seen for evolution hasn't proven anything or it would not be a theory. This is the problem with society its easier to make fun of someone rather than to listen to what they have to say. I have done extensive research on the theory of evolution yet I have found nothing to sway my believes. I grew up in a very religious family but am no longer religious. This is the reason for the extensive research I have done because I was trying to find the truth, I was trying to see if I had been believing the wrong thing. I wanted to find proof of evolution but there is none. There also is no proof of Creation. So everyone is never going to agree on this point but that doesn't mean we need to disrespect others because of this. I do not think anyone is dumb or stupid for believing evolution or creation. There are valid arguments on both sides. The problem is neither side will ever really LISTEN to the other side. Not that we all have to agree but if you actually sat down and had a healthy debate with someone about this or did a little research on your own about the subject you would see the parallels between the two. I just don't understand why we cant respect each others opinions and not attack others based on believes. I thoroughly enjoy reading articles about history regardless of the fact that I believe in God. It has nothing to do with it. Everyone is entitled to their own opinion and comments even the angry ones. But we do not have to act like we haven't "evolved" and are still uncivilized so consider that
Does the "millions of sharpshooting" idiots, ihhabiting thesilly NRA-- dream they can shoot a meteor or comet down with their hundred-round drums attached to one of their toys?
Or, prehistoric psycho and resident gun-goober, Ted Nugent's 50-caliber he like to brags about?