What killed the Dinosaurs

I have to investigate the theories concerning what killed the Dinosaurs. I was wondering if any of you know of any evidence that proves that the Dinosaurs were killed by:

I) Disease
II) A Supernova
III) Climate Change

For example: We have proof that it was the asteroid because... (microfractures in rocks, etc)
I have done the Asteroid and Volcano theory, so I don't need anything on those.

A little snippet on climate/environment change from Wikipedia:

At the peak of the dinosaur era, there were no polar ice caps, and sea levels are estimated to have been from 100 to 250 metres (330 to 820 feet) higher than they are today. The planet's temperature was also much more uniform, with only 25 degrees Celsius separating average polar temperatures from those at the equator. On average, atmospheric temperatures were also much warmer; the poles, for example, were 50 °C warmer than today.

The atmosphere's composition during the dinosaur era was vastly different as well. Carbon dioxide levels were up to 12 times higher than today's levels, and oxygen formed 32 to 35 percent of the atmosphere, as compared with 21 percent today. However, by the late Cretaceous, the environment was changing dramatically. Volcanic activity was decreasing, which led to a cooling trend as levels of atmospheric carbon dioxide dropped. Oxygen levels in the atmosphere also started to fluctuate and would ultimately fall considerably. Some scientists hypothesize that climate change, combined with lower oxygen levels, might have led directly to the demise of many species. If the dinosaurs had respiratory systems similar to those commonly found in modern birds, it may have been particularly difficult for them to cope with reduced respiratory efficiency, given the enormous oxygen demands of their very large bodies.

A short (and by my estimation, a bit "flowery") article on disease:

http://www.priweb.org/ed/ICTHOL/ICTHOLrp/69rp.htm

I think the disease theory falls short, if creatures such as the dinosaurs became extinct due to disease, why did other life survive? (Fauna that is, not flora).

A nice article on the supernova theory (for us laymens, a star going kaboom!):

http://www.lbl.gov/Science-Articles/...xtinction.html

Just do a ctrl f for the word supernova to find the related material.

~ Adhamh.

You are forgetting "evolution". There's a theory goes:

"Dinosaurs may be the kings of all the animals back in the Jurassic era (or earlier). Some said they were wiped out because of asteroid crash, others said diseases. But the reality may be that dinosaurs died out because of evolutions. As creatures at the lower food chain level began to migrate and adapt to the environment around them, dinosaurs were unable to catch their preys as easily as before. Likewise, the creatures started to mutate and evolve, turning into new species by cross-breeding and so on and so forth."

So yeah, you might want to consider this one too.

Supernova may be unlikely, for a supernova explosion to occur near Earth, everything on Earth would have been wiped out, leaving no bacterias whatsoever. Its explosion was that powerful.

The diseases theory may be plausible, for different species have different genetic coding and different biochemistries in them. It is quite possible that one species may die off while another to live on (in response to Adhamh's post). That's why the avian flu is mutating, affecting not only birds but humans as well. That's also why some species on Earth get sick while others do not.

is thr a behavior theory? insted of they're envirenment changing, prhaps teh dinos thmselves were teh ones tt changed? i thnk i red abt tt in one of michael cricton's books. not a sientific soruce, bt mr. crichton is a biologist, so i thnk his "theories" might hv sme merit (if he was teh one hoo broght tt theory up tt is.

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Is there a "behavior" theory? Instead of their environment changing, perhaps the dinosaurs themselves were the ones that changed? I think I read about that in one of Michael Crichton's books. Not a scientific source, but Mr. Crichton is a biologist, so I think his "theories" might have some merit (if he was the one who brought that theory up. that is).

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well i am reliogious so i believe the flood killed them (although the bible doesn't say that) but evalutionist believe that a astriond hit the earth, made a lot of dust, covered the sun and made a ice age

The flood couldnt have killed them because they were dead loooooong before christ was ever born! But I dont believe non of that junk cause Im an atheist.....

Anyway back on topic Id say a climate change wiped them out, the ice age I mean, the ice age of course was formed by the meteor crash of course!

from a regligous pt of view, dinos lived a few 1000 yrs ago n coexistd w/ humans. i'm sort of religous, bt i dont liek to mix religon n sience anyway.

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From a religious point of view, dinosaurs lived a few thousand years ago and coexisted with humans. I'm sort of religious, but I don't like to mix religion and science anyway.

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You might be interested in this link...
http://space.com/scienceastronomy/06...ig_crater.html

My theory, based off of factual events and statistics: First off, humans did not coexist with dinosaurs. I curse cartoons for making that what the general public believes. Okay, so, the dinosaurs were wiped out by a comet, or an asteroid. Whichever one floats your boat. (I didn't say meteor because that's the streak of light that you see when a meteoroid enters Earth's atmosphere.) Okay, so, it would take an object roughly 10 or 11 kilometers across to cause a mass extinction here on Earth, so I'll just say that the object that hit us was ten kilometers wide. Okay, so, when it hit, it kicked up a large amount of dust, which drifted all throughout Earth's atmosphere and blocked out he sun's light. Because plants rely on light to carry out photosynthesis, they were unable to survive. This caused them to die out. Then, because many dinosaurs and other reptilian animals survived on plants, they died out. This then made the carnivorous creatures to die as well. Life on Earth pretty much vanished. Well, on the surface, at least. Creatures that could survive in water were able to escape from the mass extinction, including, yes, dragons. I know, I'm crazy, but you know what, it's plausible. All over the world, cultures that have absolutely no connections have stories, myths, and legends about dragons. Because dragons had already evolved from aquatic serpents, they were able to quickly adapt back to their older forms. Their hydrogen sacs (used to breathe fire) went back to being swim bladders to help them stay floating at a certain depth. Their wings became fins, which helped them to swim. They stayed like this for millions of years, until they stepped back onto land. Since they had also been land animals before, they adapted back into their flying, fire-breathing forms. Then, they just adapted to the land around them and became one of the first creatures to die out at the hand of man. I know, it's a crackpot theory, but I saw it on television and I believe it's mostly true. Go ahead, call me crazy. I don't care. Who is more foolish? The fool? Or the fool who follows him?

I killed them. I single handedly possesed General Scales of the Sharpclaw Clan and brought terror to Dinosaur Planet. And then, when things were going well, Starfox came and ruined my fun. A couple of races went extinct, but that is about it.

Seriously, though, I believe an asteroid of an incredible size hit the earth. It cause a cloud of dust to rise up and block out the son, causing dramatic climate changes, and ultimately, another ice age. The conditions were ideal for the early mammals to flourish, because of their fur. The dinosaurs would not tolerate this cold temperature. So, in other words, the earth said goodbye to the dinosaurs and hello to the mammals.

I did, no really I did.

Anyway I think that it was Climate Change do to an asteroid that killed the dinosaurs. There is evidence that a asteroid impacted earth and that maybe a small chunk came off and became the moon.

I think the supernova theory can be safely ignored, as it would have to be the gamma rays produced by the supernova, which wouldn't be so specific as to only kill some of the life when it hit. On top of that it would require a massive star very close to Earth, say a couple hundred lightyears, there's no real sign of any supernova that would've been large enough to gamma ray burst the Earth, and if there had been we'd still have some sign of it.

As for the flood and dinosaurs, if you look a bit in the Internet: Serious Business section you can find a thread on that, my views on the matter are fairly plain, but I don't want to start that discussion here.

Oh, and just for reference, after it entered the Earth's atmosphere the asteroid would be a meteor.

To that point, I just want to add that any massive object colliding with Earth would create an extreme energy-friction on the Earth's atmosphere, leading to the creation of oven-like temperature that engulfs the entire planet and burns up everything for a brief period of time.

I forget the details but there is a theory of a near miss of a comet which superheated the atmosphere.

This thread is just pointless because nobody will ever know what truly killed the dinosaurs. And when we find out, what? Are we going to have a little celebration because we found out how something died?? It's past. History. Long gone. People should pay more attention to the future. It's like if you're running with your head turned. Sometime or later, you're gonna hit a pole.

Originally Posted by Lone Wolf

To that point, I just want to add that any massive object colliding with Earth would create an extreme energy-friction on the Earth's atmosphere, leading to the creation of oven-like temperature that engulfs the entire planet and burns up everything for a brief period of time.

No, it wouldn't. Most of the heat from a meteor impact isn't from friction, anyways. Now, a number of near-misses but sufficiently large meteors could've knocked away most of the atmosphere, but then we probably would've had a total extinction of higher life.

Originally Posted by alch3mist

didnt the ice age kill the dinosoures

Which ice age? I'm going to assume you mean the one with Mammoths and humans, in which case the answer is a resounding no, the Dinosaurs were dead long before then. If, however, you are referring to the nuclear winter like effect of having a massive meteor hit the Earth, causing it to cool drastically, then yes, you'd be right.

Originally Posted by GDwarf

No, it wouldn't. Most of the heat from a meteor impact isn't from friction, anyways. Now, a number of near-misses but sufficiently large meteors could've knocked away most of the atmosphere, but then we probably would've had a total extinction of higher life.

Actually, it would. I read that from a science article several years ago. No sources I can give, I know, but I remember vividly that they said it certainly is plausible.