What Really Killed the Dinosaurs?

Ratings: 6.83/10 from 54 users.

What Really Killed the Dinosaurs?For more than 150 million years, dinosaurs dominated Earth. They were so successful that other animal groups - mammals included - had little chance of playing anything more than secondary roles.

Then, 65 million years ago, the dinosaurs vanished from the world forever. Did they meet a quick and catastrophic end, or did they fade away gradually?

In the search for answers to what killed the dinosaurs, scientists have looked beyond fossils. Geological evidence also holds clues and has contributed to many hypotheses, working explanations of how dinosaurs may have become extinct.

The extinction mystery is far from a simple "whodunit." The same piece of evidence is sometimes subject to multiple interpretations. And, as yet, there is no obvious "smoking gun," no piece of evidence that strongly supports only one hypothesis while disproving all others. So what do we know about dinosaur extinction, and how do we know it?

Scientific evidence and observation are the building blocks of hypotheses. Initially, the same evidence and observations may support different hypotheses. As more evidence becomes available, some hypotheses are substantiated, others are disproved, and new ones are formed.

A dinosaur extinction hypothesis is a testable statement describing factors that may have contributed to the dinosaurs' demise and how long the process may have taken. Evidence, observation, and experimentation can serve to support or disprove a hypothesis. Regardless of its ultimate acceptance or rejection, though, a valid hypothesis provides direction for future scientific inquiry.

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57 Comments / User Reviews

    Reasons Voice
  1. Reasons Voice

    Nice. Always enjoy a doc. that turns an accepted schientific theory on it's ear. For me science is a process of discovery and thought, not a belief system refusing to change. Many within the scientific community are just as bull headed and obstinant as a religious zealot. They believe what they want and will yeild to no theory that opposes them. Keep thinking, Keep questioning, and keep discovering.

  2. ez2b12
  3. ez2b12

    @ dustin

    I love that doc. It is really wild to think of that much life all dieing off at the same time. Which theory do you side with? I think it was a combination of many things that caused it, thats the only thing that made much sense to me.

  4. dustin
  5. dustin

    @ez ya for sure I have done a geology paper on the subject and yes the combination is in my estimation the cause of the species die off. The Siberian traps were some crazy volcanic eruptions, but the biggest contributing factor was the destabilization of the methane ice (methly hydrate) from the ocean floor after the earth had warmed up 5 degrees from the volcanos.

  6. Reasons Voice
  7. Reasons Voice

    Combination extinction is best theory thus far. Food chain was huge issue. Plant life dieing due to methane and water level change- leads to - plant eaters die off- And finally Carnivores. The only ones to survive were the small omnivorous scavengers and other small species with lower consumption needs like amphibians etc.
    Or it was caused by the first coming of the messiah who later came as Christ and eventually as Obama. HAHA this is science leave politics out of it.

  8. Atrophy
  9. Atrophy

    Another possible source of heavy deposition of spherols and iridium could be in meteor showers like the persaids and leonids, only much more intense. None capable of causing extinction alone, however the accumulated effects of these year after year could likely amount to a good deal of destruction.

  10. Rydrin
  11. Rydrin

    Wow you guy's are smart. I get so much joy from reading the post's aswell as watching the doc's. Cheer's.

  12. Dr. Dunkleosteus
  13. Dr. Dunkleosteus

    I agree with all the above comments.

    My username approves of this doc :)

  14. ez2b12
  15. ez2b12

    I wonder if we still have a lot of methane ice on the sea floor. If so would it be viable to collect it for use as a source of energy? Surely they have already thought of this, right? Besides I don't suppose we have a methane shortage any way, probably not viable to go through the trouble of getting it from the sea floor. But i wonder if it could become unstable again, due to global warming maybe? Just a guess but it is something I will look into.

  16. ez2b12
  17. ez2b12

    As far as this doc goes, i don't know which theory to believe. They both make sense in a way. I tend toward the single impact theory, but thats probably because it is the one I have known of for so long.

  18. Atrophy
  19. Atrophy

    A fella in the doc mentioned above by dustin worked for an energy company or something and they were exploring this option. There is apparently quite a bit of it still along every major coast. A temperature increase of around 5 degrees is enough in theory to release it.

  20. Juancho
  21. Juancho

    @ Rydrin

    Reading the comments after watching the Docs is usually my favorite part ... you learn a lot from hearing opposing views, or people will add their own tidbits of info that might've been skipped in the movie ... all in all, excellent experience.

  22. Unknown
  23. Unknown

    I think the truth may lie inside mosquitos trapped in amber, sad is we still can't read genetic code like plain text, but at least we could ressurect some T rexs and try to ask them about something. ;P

  24. nick_kcin
  25. nick_kcin

    "Millions maybe billions of species gone forever perhaps not even leaving a single fossil.."
    pretty much infinity worth if you consider every genetic variant that dies without being passed on to be a potential new species, thats kind of splitting hairs though.

    In terms of completely seperate species its interesting to think of how many tiny environmental niches could be filled for maybe just a few thousand years creating some really bizzare species, only for the environment to change and render them obsolete.

    The cave salamander and all the other strange things that were shown in the caves on the planet earth episode got me thinking about this, they were some of the weirdest creatures Ive ever seen and it surely wouldnt take much for their whole ecosystem to be wiped out or replaced. when you consider that it seems obvious that the most interesting and profound examples of evolutionary adaption are almost certain to be lost in time with no traces remaining for us nosey b@#$%^&* to find. quite sad but hey thats life.

    anyway, better get on to actually watching the documentary I'm commenting on...

  26. Reasons Voice
  27. Reasons Voice

    @EZ; Depending on the depth of the methane ice it is probably cost prohibitive as a power source. Not to mention harvesting I am sure would be tricky since the temp rises as you get closer to the surface so it would likely become gaseous before breaching. If some means of temperature stablilization during harvesting at low cost could be devised I am sure it will eventually become viable. Just dont think we are there yet.

  28. Ez
  29. Ez

    @ Reasons Voice

    Thanks, for the reply. I agree that we'er not that there yet, but I think we could stablize it befor breaching. I imagine some means of keeping it under pressure on the way up, surely we could achieve this right now. I doubt though that we could get deep enough to get it with whatever device they use to maintain the pressure. Would we have to copy the pressure it is at when at the bottom? If so that might be an issue as that is a whole lot of pressure. But if it just needed a reasonable amount to stabalize, I think that part could be achieved. Like I said I think the biggest issue would be collecting and moving into the pressurized environment at that depth. Do you know the average depth it is found at?

  30. Ez
  31. Ez

    @ Atrophy

    Cool, i need to rewatch that doc. I loved it but I must have missed that part. Thanks for the heads up.

  32. nick_kcin
  33. nick_kcin

    I'm no geologist but I think that womans theory can be explained away pretty well, the spherols would've come down fairly quickly but the sand and sediment washed up from a tsunami big enough to circle the globe multiple times would take years to fully settle, and the amount that would be end up back to the original point of impact (and at the exact opposite point on the globe) would be huge compared to elsewhere because the backwash would all meet there, giving the equivalent of thousands of years worth. Not sure about the iridium though, could that remain in the atmosphere and come down later?
    The 'microscopic plankton fossils' weren't very convincing either, I'm gonna side with the other guy and say it seems there was only one major impact.
    I may be wrong though that was just the feeling I got

  34. Reasons Voice
  35. Reasons Voice

    @EZ; Not sure on the depth issue. Pressurization would be one solution the other being just simple temperature stabilization. I am sure we have the tech savy to make it happen just not in a finacially viable way. Unlike with oil where ya stick in one straw and suck away this is an active process more like mining. That being the case the operations costs go well beyond startup costs. Perhapse one more viable option would be tapping into it and allowing it to vaporize and raise on its own for collection or ideally on site consumption. However there is risk there in having essentially a power plant on a platform in the ocean. the repercussions of storm damage could be tremendous.

  36. Samoth Leonety
  37. Samoth Leonety

    They all died from a single virus infection that spread to all, such as in the case of a pandemic.

  38. Farren
  39. Farren

    It would be far better for science, and in other disciplines, if individuals and groups didn't form "cliques" around their prized theory.

    Then whenever two competing groups have to communicate or interact, they are always fighting, there is an edge of bitterness that hinders the true spirit of science.

    Science would benefit more if scientists remained impartial, objective, and follow the data always. If someone or some group finds a bit of evidence that calls the prevailing theory into question, it must be looked at and accepted (given that it is authentic).

    There's no reason to dismiss evidence because a theory is deemed too cherished. This unfortunately happens *a lot*, and slows the rate of scientific discovery for all of us.

  40. Ez
  41. Ez

    @ Farren

    Every one wants to attach their name to some kind of research that is recognized. It helps land you better jobs and more respect. Science is a bussiness and a job, just like evrything else. Musicians always want to work with the most popular band, same reason. Scientists are very rarely judged on their abilities, more on what they have their name attached to.

    When the guy that came up with m theory first started he said he couldn't get anyone to work for him. All the grad students were like, "Well if I work on string theory I can get a job." Then string theory merged/turned into M theory and now he has more grad students than he can stand. I veiw science as almost sacred, the most important thing humans do. But in reality it is subceptible to all kinds of clicks and predjudices, people with agendas, all the same stuff that makes politics and big bussiness unsavory to most.

  42. terryrret
  43. terryrret

    Enjoyed it nice to show us different sides of the science and how they see it .

  44. lizard queen
  45. lizard queen

    this just shows how thick headed mosts scientists are

    they show great contention over little details such as whether one or two asteroids destroyed the dinosaurs

    clearly they cannot handle their veiw of reality getting shifted

    objectivity? surely you jest

  46. Lori George Alexander
  47. Lori George Alexander

    I am a fan of Sherlock Holmes and he would have loved this documentary. You have a bunch of scientists trying to solve the mystery of the disappearance of the dinosaurs . They come up with different hypothesis and then look to see if the facts match and then change when they don't and explore some more and then discuss it among themselves and then look for other answers. Sure, human emotions get tangled up in their ideas after all scientists are humans. Some want to hold on to the old ideas and then the others come up with new ideas and then there are still others. I love science. I loved this documentary.

  48. GreenBee
  49. GreenBee

    I like the fact that the combination of factors exists, because more and more I begin to doubt the "bang! and they're gone" type of theories whether they are applied to the dinosaurs or to ancient civilizations which seem to "vanish in the haze" as the Beatles song goes. Science tends to be very narrow-minded in many cases, seeking for the most uncomplicated (simple) ways to explain complex, (often grand) events such as mass extinctions and the disappearances of whole civilizations. It's much easier to find evidence or to arrange evidence to fit a "Bang! and they're gone" theory than try and see the bigger picture, and maybe combine different pieces of evidence (as done in this doc) in order to come up with amore complex and believable scenario then just one minute they're here the next poof they're gone in a ball of fire. And I am one of those people who knows quiete a bit about excavation, geology, dinosaurs, and have grown up with the meteor and or the volcanic eruption theory. Great Doc. Thanks, Vlatko, mate.

  50. Felix Lapubelle
  51. Felix Lapubelle

    Earth. The punching bag of the universe.

  52. dustin
  53. dustin

    Earth. My mother and my home.

  54. Enzo
  55. Enzo

    I love dinosaurs me!! Quality doc. Its good that the accepted theory is challenged, it can only help to further our understanding.

  56. sasidhar
  57. sasidhar

    i think Samoth Leonety's(comment no: 20) view also should be considered because epidemics can also play an important role in extinction but my only doubt is it can't spread from one continent to another. at the time of extinction continents were closer than today's. so... and if they weren't distant enough for spreading ,may be flying dinosaurs could have spread it.
    i know this point has a little amount of hope but it should be given some consideration.

    this doc was great and the comments are even greater than the doc.thanks vlatko and the commentators.

  58. addy
  59. addy

    it is always a meteorite, we are the third or even fourth or more ciclus after mass extinctions coused by meteorite catastrophe

  60. Wino
  61. Wino

    Aliens killed the dinosaurs with their alien diseases!!

  62. Mr. Wonderful
  63. Mr. Wonderful

    Probably what killed them is the cavemen using them as appliances, hedge clippers, vacuum cleaners garbage disposals etc..

  64. Metavacron
  65. Metavacron

    Being less than a moment into the documentary, i came up with an idea. First of all, i'm not religious, quite the absolute opposite than that. But maybe, the biblical tale of the serpent, which is cursed to live without legs, has roots to actual facts. Considering Nature as a divine entity for civilizations before us and reptile artifacts spread over the globe, you got the concept of the particular story. But since the spectrum of perception was limited and the profits of the priests high, a reason for this animal's ''punishment'' had to be created. The rest is known and being taught even today.

  66. ruffkutt
  67. ruffkutt

    LOL ...steam shovels too, yaba daba doo...

  68. Mathew Scannell
  69. Mathew Scannell

    you think you have a crappy job!

  70. Guest
  71. Guest

    is this your real name?
    are you French? were you teased?

  72. Guest
  73. Guest

    Interesting doc.
    And if we dissapear will there be some form of life that can explain how and why we left the earth?

  74. Raghd Harmassi
  75. Raghd Harmassi

    I agree with what was said at the end of the doc, Dinosaurs certainly were the victims of various unfortunate circumstances combined together. The theory that they had been already in the path to extinction seems the most reasonable to me, the impact kind of accelerated its process, that's all.

  76. Dochka Tochka
  77. Dochka Tochka

    bulgarian subtitles :D

  78. Tony Lawrence
  79. Tony Lawrence

    I agree with Dochka; it was the Bulgarian subtitles which finally made the Dinosaurs extinct.

  80. L0LAW0NKA
  81. L0LAW0NKA

    Wait wait wait. I just watched the doc "the day the earth nearly died" and they said that those eruptions of the Siberian Traps killed off the dinos of the Permian era, and now they're saying they killed the dinos of the jurassic era!! Why are these doc not consistent? Boo, they should get their facts straight. I watched "the mystery of the jurassic" doc and these two docs and they're contadicting each other. That's not right. T____T"

  82. Karan Rao
  83. Karan Rao

    I think that the dinosaurs went extinct because of climate change and that some dinosaurs got extinct before the next time period. But after 65 million years the Dinosaurs suddenly experienced a climate change. That is how the ice age appeared.

  84. Sharon Hutchinson
  85. Sharon Hutchinson

    Dinosaurs didn't exist during the Permian. The extinction that occurred at the end of that era was much greater than that of the Cretaceous.

    The extinction that happened at the end of the Jurassic is considered minor. And the dinosaurs did not go extinct; else we would have had no T Rexs roaming around during the Cretaceous.

    You have to remember that all theories regarding the origin of extinctions are just that--theories. There are a number of them, and they are subject to change as new evidence appears. That's what science is all about. We still cannot say for sure what has caused them, so these documentaries are not contradictory. They are just different explanations for something that occurred that we are continuing to learn about.

  86. Katie Stanyard
  87. Katie Stanyard

    dinosaurs !!!!!! love them bruv

  88. LukeS
  89. LukeS

    What killed the dinosaurs on land, sea and air? Food scarcity or oxygen deprivation or some species-specific virus or a combination of all could have been their demise.

  90. Jack Dempsey
  91. Jack Dempsey

    Sorry I forget details but I recall a theory that dinosaurs had so filled the world with mounds of their own feces that disease-carrying insects took most of them down. Lots less dramatic than a meteor.

  92. stone
  93. stone

    Scientific Terms

    A hypothesis is a proposed explanation for a phenomenon.

    A scientific theory is a peer reviewed and accepted explanation for an aspect of the natural world. Theories have been thoroughly tested, and have shown to be a good explanation. A short explanation is that a theory is an accepted hypothesis.

  94. Guest
  95. Guest

    That would have made them ex stink alright, short for extreme stink:) I have never heard of that theory, I will look for it.

  96. Guest
  97. Guest

    After 150 million years on earth they may have died of boredom.
    I think it is most commonly thought that an impact was the start of a global fire storm that cause a "nuke" winter...starvation.
    I gotta check into the poo theory though:)

  98. Peter JC
  99. Peter JC

    yes, yes.

  100. J.
  101. J.

    The exact impact crater responsible. This crater is roughly 600 miles in diameter and is also responsible for the creation of most of the northern and Canadian rocky mountains. You will also see a volcano that is roughly 300 miles in diameter and is responsible for the creation of the Grand Canyon and the Colorado Rocky Mts.

  102. Jessica Smith
  103. Jessica Smith

    So my question is What clues help scientists form their theories about what killed the dinosaurs?

  104. Childofyahweh
  105. Childofyahweh

    After realising everything I learned was a lie, I'm leaning more toward what no one else seams to be thinking and that is that Yahweh (god) might have just got rid of them, not all of them but most of them to make space for us humans. That's my theory and I'm sticking too it

  106. Dave
  107. Dave

    Great doc. More evidence should be collected and studied... and results independently verified. The worm trails could be from washed up sand (from the tsunami) already containing worms... which just kept on making trails once they and the sand settled. An asteroid the size that hit 65 million years ago would certainly have created an enormous tsunami... and fall out would easily have buried land under several meters of ejecta, for hundreds of kilometers in every direction from the blast sight. Just look at how much debris builds up around your average volcano, after a major eruption. The ash alone is usually several meters thick. Now multiply that a billion fold for a 6 mile wide asteroid stiking at 20 times the muzzle velocity of a rifle bullet.

  108. Believer
  109. Believer

    I believe that during the big flood mentioned in the bible in Genesis 6 "Noah's Flood" killed them. The two of them which Noah took into his ship could not live as their food web was destroyed during in the flood.

  110. juan macker
  111. juan macker

    virus killed the dinosaurs...if there was a meteor that formed a dust cloud blocking the sun thereby creating an ice age...ALL of life would perish, not just dinosaurs...

  112. Sarah
  113. Sarah

    This is the best comment stream thank you to all the contributors for the awesome perspectives and thought out posts ?? Let's keep science moving forward

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