Geology and Earth ScienceThe Dinosaur Extinction by Joe Leddy
65 million years ago the most famous mass extinction occurred. It was at this time that all of the dinosaurs died. What most people do not know is that along with the extinction of the dinosaurs 70% of all species on Earth became extinct at that time? Therefore any theory that explains the demise of the dinosaurs must be comprehensive enough to include the extinction of the other species as well.
There are two serious theories that have gained acceptance within the scientific community to explain the disappearance of the dinosaurs, the meteor theory and the volcanism theory. Both of these theories point to the same evidence of the extinction, however, they differ on the root cause.
Analysis of the rocks in and around the end of the Cretaceous Period was conducted by a team of scientists from the University of California (Luis and Walter Alvarez) in Gubbio, Italy.
What the Alvarez’ s discovered was a thin layer of clay that contained a large quantity of the element Iridium in the rock samples. Iridium is an extremely rare element in the Earth’s crust, typically only about 0.001 parts per million. In rock analyzed by the Alverez’s the quantity of Iridium was 30X that amount, this level of Iridium is typically only found in meteorites. After the initial discovery in Italy, scientists discovered Iridium in many samples from the same layer(now know as the K/T boundary, all over the Earth. The key to the dinosaur’s extinction is in origin of the Iridium.
It is possible that volcanism could explain both the clay layer and the abundance of iridium. This theory begins with the formation of the Earth. When the Earth was still molten it was possible, and likely probable, that meteors containing Iridium continued to crash into the planet. As the planet cooled the Iridium contained in the meteors was buried deep within the mantle of the Earth.
A series of violent volcanic eruptions that would bring molten material from the mantle to the surface would have then thrust the Iridium out into the atmosphere (in addition to the tons and tons of additional particles). Once in the atmosphere these materials formed a barrier, that blocked sunlight from reaching the Earth, which led to a global cooling period and eventually an Ice Age. This shift in the global climate is what is ultimately believed to have caused the mass extinction.
The more widely accepted theory states that a large meteor (about the size of Mt. Everest) containing large amounts of Iridium crashed into the Earth about 65mya. An enormous amount of energy was released during the collision, which sent tons of debris into the atmosphere. Just as in the Volcanism Theory, this led to the serious climate changes that followed. Why should this theory be more widely accepted?
Volcanic eruptions are very common within the history of the Earth, and out-gassing (the process by which volcanoes released gas and contributed to the formation of the atmosphere) has been established to operate on a global scale.
Why would the Iridium show up in these quantities in a “single” geological event? If it is present in the Earth would we see a more uniform concentration of it, or see less of it on a more frequent basis.
The Meteor Theory explains the presence of the Iridium on a one off basis. It has been calculated that a 10km meteor, which is not that big on a cosmic scale, would contain enough Iridium to account for the levels found.
Until 1990, many geologists had asked the question “Where is the crater?” In 1990 Alan Hildebrand was reviewing some data from some scientists looking for oil in the Yucatan region of Mexico. Mr. Hildebrand uncovered a ring like structure near the small town of Chicxulub; this ring is roughly 65Million years old and 180km in diameter. This diameter is consistent with the impact of a 10km meteor.
So currently the evidence seems to suggest the Meteor Theory has some credence.
For more facts and theories see the following links and sources:
What killed the dinosaurs? http://www.ucnp.berkely.edu/diapsids/extinction.html
BBC – No fiery end
http://news.bbc.co.uk/1/hi/sci/tech/3295539.stm
Historical Geology 4th Edition by Wicander and Monroe
www.Enchantedlearning.com
The Dinosaur Extinction Page by Andrew Buckley
21 Comments:
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With all of evidence pointing to a meteor hitting the earth it is a real eye opener. As with the volcanism theory, the Meteor theory really shows the mortality of all the species on earth. It is good to know what could have happened in the past, because it could happen again in the future.
I would have to agree with the more accepted theory, the Meteor theory. Sixty-five million years ago there was a lot more space material present in the universe. The amount of collisions was higher and the likeliness of a larger piece of debris hitting the earth would be considerably higher, sixty-five million years ago than it is now. Also, with the discovery of a crater large enough and old enough to match the suggested meteor, it is clear to me that the evidence is supported fully.
I also believe that the event that caused the dinosaurs to become extinct would have to be like nothing that the species on earth have ever experienced. There were volcanic eruptions throughout earths’ history. The likeliness of a meteor that size hitting the earth is less likely to happen than something that is occurring on the earth on a regular basis.
This leads back to the fact about the Iridium. Could it be possible that that much Iridium would be able to be put into the earths crust from a volcanic eruption, when the souce of the Iridium is earth itself, which doesn’t exist on earth in an abundance? Also, the comment that the author made about how the Iridium was only found in one strata of rock is unlikely from a volcanic eruption. If that amount of material was deposited in one layer of rock, what are the chances that most of the known Iridium was deposited in one layer. There should be traces of Iridium in other layers as well, if this material was originally from earth. I agree with all that was said in the original document. I do feel that the more probable cause of the extinction was the Meteor Theory.
I find it fasinating that scientists are able to disern between two catasrophic events. It is absolutely amazing that we can figure out what happened millions of years ago.
Granted I never fully believed in the meteor theory, but I’m still not sure I agree with the volcanic theory either. Most life forms were found in and after the Cambrian, up until the mass extinctions in the Ordovician, Devonian, and then the “mother of all mass extinctions,” the Permian. But mass extinctions don’t happen overnight or with the snap of fingers - it takes years and years for a species to die out, even a great number of species.
I agree that an Ice Age might have done the dinosaurs to extinction. I doubt they were built to withstand freezing temperatures. I understand that the volcanoes trigged the blockage of the sun and therefore colder temperatures, but weren’t all the “violent volcanic eruptions” over with after the Hadean? That was when the earth was unstable and landmasses were being created left and right. So what trigged such an outbreak of volcanic eruptions millions of years later? Yes, volcanic eruptions were common in earth’s history, but that late?
The Ice Age could have been brought on by either the meteor or volcanic theory, because either one would have caused atmospheric changes. Both these theories also explain the high amounts of Iridium that accumulated on the earth’s crust. Now that the question of where a crater of such a humungous magnitude might actually have landed has been added, the theory holds more water to a lot of people, but I still remain doubtful.
I realize the earth’s climate did a drastic change when it went into the Ice Age. Something could have triggered it, because usually an Ice Age came about only when the earth’s continents were all clustered together into a giant super continent, like Pangaea. Thus, we’d have snowball earth, because the earth’s water is all on one side of the continent, reflecting the rays of the sun and not heating up the continents, because there’s no water, or not enough water, in the center of the continent to heat it up, and so we have a huge Ice Age until the continent shifts again.
Couldn’t the Ice Age alone have caused the mass extinction of the dinosaurs?
Looking back, I disagree with the author’s thoughts about Iridium. What are the chances of it being in one rock, as well as the chances of it not being released in earlier volcanoes? Wouldn’t it have been metamorphosed by being exposed to such extreme heat and pressure?
I must admit, the meteor theory looks more and more plausible with all the evidence being accumulated on it, but I’m not completely swayed. There is the crater in Chicxulub to consider, and granted it dates back to the dinosaurs extinction, as well as the right estimated size of the one that likely caused the layer of Iridium. Until some other theory comes along that can’t be shot down my science and critics, the meteor theory will continue to stick.
Reading about things such as extinctions really makes me aware, yet again, of my mortality. This is due to the idea that Earth is a story of cycles and all that inhabit it have cyclical patterns of existence. There have been so many extinctions and all have the same sort of pattern with the strongest surviving these huge natural “disasters,” as we would call them. Then, out of the ones who survived flourishes this new population which spreads around the planet and, again, a large chunk of them die with the next mass extinction.
This will definitely happen to us for one cause or another and I bet it will be terrible to experience if I happen to be alive for it. But, besides that I believe it speeds up the process of evolution in a way. This is by a population being forced to rid of the weak and single out the strong quicker than this process usually occurs, over millions of years. It’s like starting form scratch. If this hadn’t happened with the dinosaurs, a lot of the species here probably wouldn’t be here or it would have taken a lot longer for them to become what they have become.
As for what I think about the actual article, besides the tangent about the topic of extinctions, I find it really interesting that people work so hard and dedicate their lives to prove very specific theories such as the ones that caused the dinosaurs extinction. I am glad to see that there are some people who are headstrong in their theories. These are the people who will help science to evolve. Once we know the actual cause of the extinction, I am sure that information will link with many other theories that need to be explored in Earth’s geologic and even biologic history.
I don’t have a very strong opinion on which has more evidence backing it or which one I think it was. This is because I haven’t done heavy studies to know enough information about either and I would hate to chose a side that I didn’t have facts to support my choice with. If I had to choose between the two theories, I would agree with the meteor theory. This is most likely mainly because while growing up we were told that this was the cause, but besides that it seems most logical in that to wipe out such a large population in such a quick time, the cause must have occurred suddenly with no given time for the population to adapt to the change(s).
Alli had stated that volcanic eruptions weren’t supposed to be too violent after the Hadean and I believe I remember learning that volcanic eruptions still happened rather regularly. So then what would be the cause for the change in chemicals that the volcanoes spewed out? Its seems that there isn’t enough evidence to back this up as opposed to the meteor theory where we know that a meteor hit, we know where it hit, and we know it hit relatively around the same time that the dinosaur extinction occurred.
Reading about things such as extinctions really makes me aware, yet again, of my mortality. This is due to the idea that Earth is a story of cycles and all that inhabit it have cyclical patterns of existence. There have been so many extinctions and all have the same sort of pattern with the strongest surviving these huge natural “disasters,” as we would call them. Then, out of the ones who survived flourishes this new population which spreads around the planet and, again, a large chunk of them die with the next mass extinction.
This will definitely happen to us for one cause or another and I bet it will be terrible to experience if I happen to be alive for it. But, besides that I believe it speeds up the process of evolution in a way. This is by a population being forced to rid of the weak and single out the strong quicker than this process usually occurs, over millions of years. It’s like starting form scratch. If this hadn’t happened with the dinosaurs, a lot of the species here probably wouldn’t be here or it would have taken a lot longer for them to become what they have become.
As for what I think about the actual article, besides the tangent about the topic of extinctions, I find it really interesting that people work so hard and dedicate their lives to prove very specific theories such as the ones that caused the dinosaurs extinction. I am glad to see that there are some people who are headstrong in their theories. These are the people who will help science to evolve. Once we know the actual cause of the extinction, I am sure that information will link with many other theories that need to be explored in Earth’s geologic and even biologic history.
I don’t have a very strong opinion on which has more evidence backing it or which one I think it was. This is because I haven’t done heavy studies to know enough information about either and I would hate to chose a side that I didn’t have facts to support my choice with. If I had to choose between the two theories, I would agree with the meteor theory. This is most likely mainly because while growing up we were told that this was the cause, but besides that it seems most logical in that to wipe out such a large population in such a quick time, the cause must have occurred suddenly with no given time for the population to adapt to the change(s).
Alli had stated that volcanic eruptions weren’t supposed to be too violent after the Hadean and I believe I remember learning that volcanic eruptions still happened rather regularly. So then what would be the cause for the change in chemicals that the volcanoes spewed out? Its seems that there isn’t enough evidence to back this up as opposed to the meteor theory where we know that a meteor hit, we know where it hit, and we know it hit relatively around the same time that the dinosaur extinction occurred.
Reading about things such as extinctions really makes me aware, yet again, of my mortality. This is due to the idea that Earth is a story of cycles and all that inhabit it have cyclical patterns of existence. There have been so many extinctions and all have the same sort of pattern with the strongest surviving these huge natural “disasters,” as we would call them. Then, out of the ones who survived flourishes this new population which spreads around the planet and, again, a large chunk of them die with the next mass extinction.
This will definitely happen to us for one cause or another and I bet it will be terrible to experience if I happen to be alive for it. But, besides that I believe it speeds up the process of evolution in a way. This is by a population being forced to rid of the weak and single out the strong quicker than this process usually occurs, over millions of years. It’s like starting form scratch. If this hadn’t happened with the dinosaurs, a lot of the species here probably wouldn’t be here or it would have taken a lot longer for them to become what they have become.
As for what I think about the actual article, besides the tangent about the topic of extinctions, I find it really interesting that people work so hard and dedicate their lives to prove very specific theories such as the ones that caused the dinosaurs extinction. I am glad to see that there are some people who are headstrong in their theories. These are the people who will help science to evolve. Once we know the actual cause of the extinction, I am sure that information will link with many other theories that need to be explored in Earth’s geologic and even biologic history.
I don’t have a very strong opinion on which has more evidence backing it or which one I think it was. This is because I haven’t done heavy studies to know enough information about either and I would hate to chose a side that I didn’t have facts to support my choice with. If I had to choose between the two theories, I would agree with the meteor theory. This is most likely mainly because while growing up we were told that this was the cause, but besides that it seems most logical in that to wipe out such a large population in such a quick time, the cause must have occurred suddenly with no given time for the population to adapt to the change(s).
Alli had stated that volcanic eruptions weren’t supposed to be too violent after the Hadean and I believe I remember learning that volcanic eruptions still happened rather regularly. So then what would be the cause for the change in chemicals that the volcanoes spewed out? Its seems that there isn’t enough evidence to back this up as opposed to the meteor theory where we know that a meteor hit, we know where it hit, and we know it hit relatively around the same time that the dinosaur extinction occurred.
The article on the theory of how the dinosaurs died is a thought provoking piece that is left up to much debate. The article left out a theory of mass extinction by one particular scientist who concluded it that dinosaurs and many other species might very well have died of disease rather the drastic climate change. Since scientists have discovered such a large amount of Iridium in rock layer dating back to the Cretaceous period when the dinosaurs died out, I guess that theory can be officially ruled out.
The article gave two very specific theories that can account for the massive amount of Iridium that existed when it normally wouldn’t without a major geologic event on earth. Both theories are well thought and are the best that the scientists have as of now in my opinion. The mass volcanism theory proclaims that a brief age of mass volcanic eruption across the whole earth could account for the massive amounts of Iridium all over the world along with a drastic change in climate.
We know that massive volcanic activity would emit smoke that could block out the sun and reduce the heat of the earth and plant life. We also know that the Little Ice Age that lasted roughly from 1550-1850 was the result of volcanism that directly affected the temperature in the northern hemisphere for quite a long time, or at least that is the best conclusion that scientists have been able to draw. The only problem I have with the theory is the explanation of all the Iridium.
The theory concludes that some time during the formation of earth, Massive meteorite bombardment occurred and that these meteors have Iridium. The Iridium have had to have buried itself under layers of the earth and then been brought up from the mass volcanism. I find it very unlikely that this could have happened because of the fact that the amounts of Iridium found at this time were thirty times the amount that normally would exist on earth or in rock layer. Also, Scientist aren’t exactly sure how much or how many meteorites crashed into earth during it’s formation. We can believe it was much more hitting the surface due to the fact that there was no atmosphere to slow them down or burn them up completely. But I personally feel there is room for much debate and when I look up to the moon today, I’m faced with physical evidence that the moon being much closer to the earth during its formation, might very well have taken most of the brunt of these meteorite bombardments.
The best theory to rely on in my opinion would be that of the gigantic meteor that hit the earth some time in the late Cretaceous period. The tremendous meteor would have caused a cloud of dust and debris (containing Iridium) to cover the earth leading to the weak sunlight, cooler temperatures and massive extinction of plant and animal life. With the discovery of the huge crater found in the Yucatan peninsula in Mexico, it became more easily to believe in this theory due to the estimated size of the meteor. A crater of its size would need a meteor of about 10km I diameter to have formed it. This would most likely covered the earth in debris after impact causing the mass extinction. Scientists also know that these massive meteors or asteroids pass within close proximity of the earth every era or so.
The author also gave great website for the reader to look at and find out more information and theories that are very helpful. All in all it’s a great article and accurate but it’s best that scientist go with the massive meteor theory for there explanations.
I do think thats its true that the dinosaus were whiped out by a massive meteor . The only problem i have is the time frame at which it was done . In the article the author said that the 70% of the dinos were taken out roughfly around the same time . i personaly dont think so , I think it was a long death for the dinosaurs .
Diffent parts of the article are also a little shady to me . I think if a meteor the size of mt.everest hit the earth , it would through it off its axis . Plus wheres the mountainous crater form the after shock ? Now i know that quite possibly it was filled in with sediments but it just seems outlandish to me . If all dinosaus were whiped out then wouldnt we have to start the evolustion of reptiles and sea animal all over . Plus we know from studies that dinos are the ancestors of birds . So they would have to develop all over again . With the fact of natural selection , This means that something mus have survived . Weather it be one dino . So then were the dinosaus really all extinct ? Was there one that didnt feel the after shock of a massive meteor , of volcanic eruption ? I dont think it was ass massive as everone says it was acctualy , I know we have solid evidence of the KT boundry but i dont think its a solid stand point .
The impact crater was the size of the ukatan peninsula located near the equator , and i find it hard to belove that debits would spread from one hemisphere to another i.e austraila or somthing of that sort . Now im not saying that that theory is wrong , or this didn't happen but its a little over the top for me .
I think what really happened was a series of metoers hit the earth . Not just one but a few , in key spots that created enough damage to kill massive gene pools in high populated areas .
At the close of the Jurassic the dinosaur species became almost completely wiped out. Some suppose there was some sort of a catastrophic event, whether it is a meteor, volcanism, exposure to too much radiation, possibly the flood, and the list goes on. It has been a long over speculated topic that nobody can really figure out. Throughout the many years many ideas were raised(about their extinction) and some seemed promising however, there was a downfall to each one why it could not be so. Scientists have struggled to answer these dinosaur wonders. Dinosaur fossils have been well preserved in the fossil record however scientists still can not get an exact reasoning for their extinction. When I was growing up I was lead to believe that things (like the dinosaurs) died out because of the flood, and only certain animals survived because they were on the boat with Noah. I know many people who were taught to believe this. I try to envision this miraculous boat as big enough to hold all those creatures, big and small, and I must say it is hard for me to imagine. How could they manage to adequately feed all the animals and store all of it? How could all the animals live together in a state of peace with one another? However I don’t believe I have the answer to state whether or not this is true? Could be, Could not be? Could it have been the change in climate that killed them off? Possibly they could have been extinct due to starvation, since there was a disappearance of plants they fed upon due to the climate change. Seems like it can be a number of possibilities, but I believe it was because of the starvation. Even though they seem like these “strong” reptiles unable to become extinct, a majority of them did. That rings a bell for me to believe that it must have been a loss of food or possibly a drastic climatic change. In a matter of time, large amounts of dinosaurs and other species would just die off. The reason some species lived, I believe, because their food group was not harmed and therefore they did not starve. I guess the reason why so many Paleontologists look into the extinction of dinosaurs is because they were and still are the most breathtaking and captivating creatures. I could not imagine looking above me to see a dinosaur as big as 16 feet high and 80 feet long. These reptiles also weighed remarkable weights like 40 tons and more, it’s unimaginable! I often wonder what it would be like if they still were around, I would not come out the house. It is unfathomable that something like dinosaurs could ever be defeated, like the unimaginable titanic sinking and failing all of its believers. Charles Darwin was right, only the survival of the fittest do survive
in response to Matty i, matt i would normally agree with you on the difficulty you have believing that all dino life was extinct in one occurance. You had mentioned that you believe that it was a longer death and it very well could have been, but if it was then would'nt all fossil have to be sorted in all the different layers of sediment? I dont know if they are or not i just thought i might be a nice little food for thought or more like a snack, cookies or even cheese and crackers what ever you have a taste for. My thoughts are that maybee its possible that Dino's became extinct due to some type of disease, or other sickness. I wonder if scientist could tell by the bone of the animal... i guess they would have found something that conclusive out already if they could use that kind of technology though hmmmm. going back to the article it says that it was possible that it was due to a volcanic eruption and that the iridium found in the earth was from previous meteors striking the earth, the uridium was then ejected into the sky, then settled. i just think that we would be able to find other levels of that same uridium if that was the case. The meteor theory seemed only realistic in hollywood until recently in class when we discussed the crater rings found in the cancun area thats kind of compelling and i guess im just going to go with metoer theory.
i have a few ideas about the various arguments regarding the dinosaurs. the first is the meteor argument its kool and i feel that hollywood makes its bery believeable, i however never truly believed it until recently when we discussed it in class and we went over the recent findings of the crater rings found in the cancun area, also the amount of uridium found on earth as a layer is the same amount a metor might have conentrated into it, thats pretty compelling so that arguments gets a five.
the argument regarding the idea of a volcanic eruption causing the extiction is midly compelling only because we have witnessed in the life time of man, volcanic eruptions however the amount of uridium content does'nt add up entirely with the volcanic eruption idea so its thought that the meteors that have been hitting earth before the eruption may have been ejected in to the sky then settling down. not to compelling i give it a 3
the final argument about a disease or other sickness causing the extinction seemed like a possibility at first but theres no way to truely know this unless scientists could extract further information from fossils... seems to me that they would have already discovered something that profound so due to lack of evidence i give it a 2.... nah a 2.5
so according to my extremely accurate grading scale lol the winner is the meteor argument because it has the most compelling evidence and its more entertaining to envision dinosaurs being insinerated... that sounded vaguely sadistic...gtjtpy
I am never to sure what to believe when it comes to dinosaurs. I think it might be because of the way it is taught to us as children. The whole dinosaur theory is presented to us in such a child like manner. I feel you never learn the truth. This dino is red, this one is blue. My favorite the brontosaurus, it does not even exist they made a mistake. They can never really know what color they were of how they lived and acted. With that reasoning how can they be sure how they really died. I agree something must have happened because most of the bones are dated to a mass death date. Or are they? I was most impressed with hearing that 70% of species also became extinct. I never even realized there were others. I still have a silly vision of a t-rex just wandering around eating all the other peaceful dino's. Both theories sound logical and it is hard to know which one is right if any. And to lean towards the one that repeats in our history is also a logical thought. But if all these species dyed off to never been seen again, why could it be that what ever killed them is something we will never see again or had seen since then. It could have been something we could not comprehend. Could we of thought of dinos if we found no evidence. It makes you question what else is out there. What makes them so sure it could be something they could explain or even remotely understand?
See i personaly do believe that teh dinosaurs were wipped out witha huge meateor but that couldnt of been the whoel problem. One reason can be that the meteor landed on the earth it shot up aerisols with blocked the ozon layer witch killed all the plants so after abouth thousand of yeers the dinosaurs started to vanish. But other reason can be the volcanos witch went off during that time the movemnt of pangea seperation carnavors from verbavors. But who really noes what happened maby it just could of been there time to die and start a whole new life form
Why did the dinosaurs and two-thirds of all living things vanish from the face of the Earth sixty five million years ago? I agree with the theory that a asteroid hit the earth. A large ball of ice or rock as big as a small country was turned into a cataclysmic weapon when it impacted with the earth, creating a shock wave that melted and in some cases vaporized the land for miles around it. Terrible as the immediate, direct effects of the impact were in the surrounding region, they probably would not by themselves caused the disappearance of whole families of plants and animals forever. It is logical to think that survivors in remote regions would have repopulated the devastated regions in the years following the impact. And yet an enormous mass extinction did follow the impact and now that I understand from class some of the longer term effects of a global disaster like a large meteor hitting the earth I believe that the dinosaurs died from the secondary results of the impact.
Within the weeks after the impact the immediate effects should have died down. I believe the earth would have turned cold and dark. Vast quantities of fine dust and ash that was violently thrown through the atmosphere settled there, blocking any sunlight from getting through. The land became so dark that you could not have seen your hand in front of your face, and this darkness and the accompanying cold probably lasted for many years. Sea and land temperatures must have dropped dramatically and quickly. The climate went to the opposite extreme. What once was a tropical paradise turned into a freezing, dark hell. It was a world dark and frozen, poisoned by ash and soot.
Eventually the ash and soot would have settled out of the atmosphere. The two major greenhouses gases, carbon dioxide and water vapor must have been released in large quantities from the site of the impact. The water vapor was probably removed from quickly from the atmosphere as rain which washed out the dust. Carbon dioxide can only be removed slowly from the air, and it trapped heat from the sun, raising temperatures to sweltering levels. It was probably many years before the carbon dioxide went back down to normal levels. Not only did water and carbon dioxide rain out of the atmosphere but there was also acid rain. This sulfuric acid came from sulfur in the sediments around the impact site. Like today, such large quantities of it gathered in the atmosphere that it turned into acid rain, harmfully damaging plants and animals.
The loss of the dinosaurs is probably related to their position in the food chain, with herbivorous dinosaurs eating vegetation and carnivorous dinosaurs eating herbivores and small mammals. During the years of cold and darkness cast by the clouds of dust in the atmosphere, plants would wither and the herbivores would starve, and so would the carnivores in their turn. Large animals are never as abundant as smaller ones, especially top carnivores, so they would have been particularly vulnerable to extinction. This domino effect was amplified by the larger metabolism and reproduction requirements of large-sized animals. The sudden loss of over 75% of the plants and animals on Earth is a catastrophe almost incompressible to us. It truly marked the end of a world.
I have never read about any other theories explaining the reason behind Dinosaur extinction, but after reading about these two theories, I now have some insight about these phenomena. There would have to of been a huge change in the earth’s climate because what else could have some effect that would kill off 70% of all life. That is a huge number. These two theories do very well explaining what “may” have occurred. I say what “may” have occurred because to me all of this is speculation. From the iridium and outgassing to a huge meteor creating an enormous amount of energy dispersing debris into the atmosphere, are exactly what scientist say are the theories.
The first theory is quite genius if you think about it. It says that a meteor filled with iridium landed on earth when it was in its molten lava period and then was dispersed into the air through outgassing creating a shield and therefore, blocking the suns rays. This is either a well thought up idea which I hope and presume, or it is a student that just put geology terms together to explain this phenomena. I find this especially interesting because I have sunglasses that block uv-rays and they are made out of iridium or at least some form of it, which is just something to think about. How much iridium would have to be placed in the atmosphere to accomplish this? If I remember correctly iridium is not an abundant mineral. Where is the iridium today? From the knowledge that I have gathered the Hadeon was the period earth was in its molten lava stage and dinosaurs did not exist at this time. So what is being said here is that millions of years the iridium was outgassed. This is very hard to believe but still it is genius. It’s like a homework question I received. I was given a setting and I had to tell what happened in the past knowing that the earth acts the way it does now as it did then. I speculated using terms and examples and that’s what I think this theory is.
Because what one of the other comments that was left I leaned more towards the second theory which I will still say is a speculation simply because I did not do the research myself and I do not trust people and their word for it. That is faith and this is not a religion. We are trying to find the truth about the history of our world. There are a few methods that I came across that would lead me to believe something is a fact, or the truth. I would need to know how this theory was created but I guess that’s why it is a theory. So what do humans do? Lean towards what makes more sense. Now, back to what the student said, which was that the earth was not made of lava anymore so the meteor would have had a hard time being submersed in lava but rather it would just have had an impact. This impact would have caused devastation on a horrific scale. This impact would not be in the lava but rather on the continents.
Another thing a student said that I found very interesting is “why couldn’t a glacier period that was caused by pangea, like formation, kill the dinosaurs?” I like this theory because couldn’t you use paleomagnetic techniques to see where continents were and if they were together 65mya. I mean, dinosaurs are one of the reasons we put pangea together. They were able to roam from one content to another and that’s why we found fossils in the areas we did. Was another pangea forming when the dinosaurs roamed and they just happened to live and die during an ice age.
Posted for Liz
It’s very difficult for me to believe that dinosaurs were walking on this earth more than 65 million years ago. 65 million years ago sounds so far away to even imagine it. I try to imagine that these dinosaurs walked the earth, all the different kinds and sizes, but when I start thinking about how big some of them were is when I start to not believe. However it did all happen, dinosaurs did walk the earth, and the only reason I have accepted that it is true is because of all the evidence that we have. Every time I go to the museum of natural history it amazes me. I always stand there wondering ok if this really did happen where did they go. What happened?
There’s two theories of the mass extinction; volcanic and the meteor. They both have supporting facts to prove there was a mass extinction. If I had to pick one theory to be more true than the other, I would have to say that the meteor theory is more logical. For one because it’s widely accepted. Almost any movie or science class the meteor extinction is favored. Secondly, the fact that in 1990 Alan Hildebrand uncovered a ring like structure that was around 65 million yrs old and was said to be a crater that was 10k thick. This should be enough evidence alone to push aside the volcano theory. Could you imagine seeing a meteor the size of Mt. Everest? That’s crazy. And on a cosmic scale that wasn’t even that big. It sounds logical that the meteor did contain iridium and released large amounts of energy at the collision and sent tons of debris into the atmosphere leading to serious climate change, therefore a mass extinction. It could be possible that the volcano could explain the iridium as well however, there had to be mass eruptions to bring molten material from the mantle to the surface and then thrust iridium into the atmosphere. It sounds more complicated than one huge meteor.
The fact that Alvarez discovered a thin layer of clay that contained iridium is basically the only evidence we have of the mass extinction taking place 65 million years ago. Iridium is extremely rare; the rock sample taken from the thin layer contained so much iridium that is typically only found in meteors. This layer is now known as the K/T boundary. It’s odd that above the K/T boundary there is no evidence of dinosaurs but below there is.
Who’s to say that the iridium really did come from a meteor? There is no absolute fact of the mass extinction of dinosaurs. How do we know something didn’t happen 65 million years ago that scientist have yet to uncover?
The meteor theory is something that I have always had my doubts about. The world is a big place and the fact that a majority of the worlds population died out because of a big meteor is something that has not yet convinced me. How can the hit by a meteor affect populations all the way around the globe? The oxygen levels could have decreased but it wasn't something that would happen quickly. It would take a while to reach the other side of the earth. Also the idea I got out of the K.T boundary was that it happened due to the cloud of dust from the meteor. If this is the case then why don’t they find any dinosaur fossils in the K.T. boundary itself?
From Anthony Angione
The extinction of the Dinosaurs has and always will be a fascinating topic to me. What could have caused such a sudden mass dissapearance of life on this planet. One day Dinosaurs roamed the earth as kings. They were such mighty creature how did they come to an end. Why did they vanish. If only one could take a time machine and travel back 65 million years ago to that moment in history and find out what happened.
The two theories of the mass extinction are volcanic activity and the meteor. There is some evidence to support both killed the dinosaurs. A comet sounds most likely. The earth is literally covered in craters from meteor impact zones including a big one on the Yucatan peninsula. It came about the same time as the dinosaurs went extinct I believe and then destroyed the creatures there and put dangerous chemicals into the atmosphere that killed off the rest. It is strange that at the K?T boundary there are no more fossils of dinosaurs. A sudden quick thing must have happened to kill off the creatures. The only logical thing seems to be a meteor. The idea that a volcano killed off the dinosaurs is unlikely. There would need to be a one huge volcano in order to wipe out the dinosaurs across the earth. It doesn’t seem possible.
What happened to the dinosaurs is still unclear. One should invent a time machine and see what happened to find out. What is scary is if a sudden thing killed off the dinosaurs, could it happen to us. All we know is 65 million years ago something inexplicable happened. If history does repeat itself we may be next.
The extinction of the Dinosaurs has and always will be a fascinating topic to me. What could have caused such a sudden mass dissapearance of life on this planet. One day Dinosaurs roamed the earth as kings. They were such mighty creature how did they come to an end. Why did they vanish. If only one could take a time machine and travel back 65 million years ago to that moment in history and find out what happened.
The two theories of the mass extinction are volcanic activity and the meteor. There is some evidence to support both killed the dinosaurs. A comet sounds most likely. The earth is literally covered in craters from meteor impact zones including a big one on the Yucatan peninsula. It came about the same time as the dinosaurs went extinct I believe and then destroyed the creatures there and put dangerous chemicals into the atmosphere that killed off the rest. It is strange that at the K?T boundary there are no more fossils of dinosaurs. A sudden quick thing must have happened to kill off the creatures. The only logical thing seems to be a meteor. The idea that a volcano killed off the dinosaurs is unlikely. There would need to be a one huge volcano in order to wipe out the dinosaurs across the earth. It doesn’t seem possible.
What happened to the dinosaurs is still unclear. One should invent a time machine and see what happened to find out. What is scary is if a sudden thing killed off the dinosaurs, could it happen to us. All we know is 65 million years ago something inexplicable happened. If history does repeat itself we may be next.
Its pretty hard to say how Dinosaurs became extinct. I have always be interested in dinosaurs, the time in which they lived in and how they lived. I never really put to much though in to how they become extinct. I guess it
because you can never be sure. Its been how many years and we still don't know what happened to them. We aren’t even 100% sure on that they looked like. You always see dinosaurs being green, red and blue, but how do you know. What if they were dotted. Another thing that I always wondered was what if they could talk? I doubt that they did but you never know and you'll never know. As I was reading through everyone’s response I like all of the theories of extinction. It can possible be that they are all right. That one happened first and set off the rest, and over a long period of time the dinosaurs became extinct. 65 million years ago is a long time ago. The earth as it is today was going though changes. The changes back then though were more drastic. Maybe
volcanic activity, the meteor and sickness killed them off. The Meteors hit the earth killing off some dinosaurs, and the meteors caused the volcanoes to all go off. Over time the dinosaurs being so big had no were to go and no
food to eat because the plant life and dinosaurs were all dead. Then with out food and bad air they became sick and died.
It is known that the main cause of dinosaur extinction is in the origin of Iridium. Many scientists have their persoanl thought or theories on this idea of extinction as well. From what i have learned, volcanoes do not erupt that often. Mt. Etna is a volcano in Italy where both my parents grew up, my father told me that only one time did it take out one town. Although it did damage to one town, the towns in itlay arenot that big. In order for volccanic explosions to cause severe damage to the entire earth, the errutption must be intense and frequent. At the same time, it is a toursit attraction where people can actualluy climb the mountain. IF it was that dangerous and it if would erupt frequently, then why would it be possible to live near of even to visit on a vacation? Still, if it did in fact happen there are so many other particles in the lava and gases that were thrown into the atmosphere. In the other aticles i have read in the blog, specifically ICE AGES by Joe Leddy, the main factors that cause an ice age are carbon dioxide and methane, variations in the earths orbit around the sun, and the arrangements of the continents places apart. The theory i feel confident in, when reading this article, is the theory in which a large meteor crashed into the earth sixy five million years ago. Scientists have proven that meteors are filled with Iridium. This theory proves that the damage that was fone was a one shot deal; the damage to the atmosphere happened right away. It was not a series of reoccuring meteoritesm or even multiple erruptions of the volcanos. This theroy became even more credible when the crater was found in Mexico in 1990.
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