10 Myths About Dinosaur Extinction

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Truths, and Untruths, About the Extinction of the Dinosaurs

K/T meteor
An artist's impression of the K/T meteor impact (NASA).

We all know that dinosaurs vanished off the face of the earth 65 million years ago, a mass extinction that still lingers in the popular imagination. How could creatures so huge, so fierce and so successful go down the drain virtually overnight, along with their cousins, the pterosaurs and marine reptiles? The details are still being worked out by geologists and paleontologists, but in the meantime, here are 10 common myths about dinosaur extinction that aren't quite on the mark (or supported by the evidence).

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Myth - Dinosaurs Died Quickly, and All at the Same Time

Baryonyx, a meat-eating dinosaur of the Cretaceous period (Wikimedia Commons).

According to our best knowledge, the K/T (Cretaceous/Tertiary) Extinction was caused by a comet or meteor that plunged into the Yucatan Peninsula in Mexico, 65 million years ago. However, this doesn't mean that all the world's dinosaurs died instantaneously, howling in agony. The meteor impact raised a huge cloud of dust that blotted out the sun, and caused the gradual demise of a) the earth's vegetation, b) the herbivorous dinosaurs that fed on that vegetation, and c) the carnivorous dinosaurs that fed on the herbivorous dinosaurs. This process may have taken as long as 200,000 years, still a blink of the eye in geologic time scales.

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Myth - Dinosaurs Were the Only Animals to Go Extinct 65 Million Years Ago

Plioplatecarpus, a mosasaur of the late Cretaceous period (Wikimedia Commons).

Think about it for a second. Scientists believe the K/T meteor impact unleashed a blast of energy equivalent to millions of thermonuclear bombs; clearly, dinosaurs wouldn't have been the only animals to feel the heat. The key difference is that, while numerous species of prehistoric mammals, prehistoric birds, plants and invertebrates were wiped off the face of the earth, enough of these creatures survived the inferno to repopulate the land and sea afterward. Dinosaurs, pterosaurs and marine reptiles weren't so lucky; they were exterminated down to the last individual (and not only because of that meteor impact, as we'll see further on).

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Myth - Dinosaurs Were Victims of the First-Ever Mass Extinction

Acanthostega, a type of amphibian that went extinct at the end of the Permian period (Wikimedia Commons).

Not only isn't this true, but you can make the case that dinosaurs were the beneficiaries of a worldwide disaster that occurred almost 200 million years before the K/T Extinction, known as the Permian-Triassic Extinction Event. This "Great Dying" (which may also have been caused by a meteor impact) saw the extinction of a whopping 70 percent of terrestrial animal species and more than 95 percent of ocean-dwelling species, as close as the world has ever come to being completely scrubbed of life. The archosaurs ("ruling reptiles") were among the lucky survivors; within 30 million years or so, by the end of the Triassic period, they had evolved into the first dinosaurs.

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Myth - Until They Went Extinct, Dinosaurs Were Thriving

Maiasaura, a hadrosaur of the late Cretaceous period (Wikimedia Commons).

You can't make the case that dinosaurs were on the top of their game when they bit the Big Cretaceous Weenie. According to a recent analysis, the pace of dinosaur radiation (the process by which species adapt to new ecological niches) had slowed down markedly by the middle of the Cretaceous period, the result being that dinosaurs were far less diversified at the time of the K/T Extinction than birds, mammals, or even prehistoric amphibians. This may explain why dinosaurs went completely extinct, while various species of birds, mammals, etc. managed to survive into the Tertiary period; there were simply fewer genera with the adaptations necessary to survive hundreds of years of famine.

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Myth - Some Dinosaurs Have Survived Down to the Present Day

loch ness monster
Some people insist the Loch Ness Monster is a living sauropod (Wikimedia Commons).

It's impossible to prove a negative, so we'll never know, with 100 percent certainty, that absolutely no dinosaurs managed to survive the K/T Extinction. However, the fact that no dinosaur fossils have been identified dating from later than 65 million years ago--combined with the fact that no one has yet encountered a living Tyrannosaurus Rex or Velociraptor--is solid evidence that dinosaurs did, indeed, go completely kaput at the end of the Cretaceous period. Still, since we know that modern birds are ultimately descended from small, feathered dinosaurs, the continued survival of pigeons, puffins and penguins may be some small consolation. (For more on this subject, see Did the Dinosaurs Really Go Extinct?)

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Myth - Dinosaurs Went Extinct Because They Weren't "Fit" Enough

Nemegtosaurus, a titanosaur of the late Cretaceous period(Wikimedia Commons).

This is an example of the circular reasoning that plagues students of Darwinian evolution. There's no objective measure by which one creature can be considered "more fit" than another; it all depends on the environment in which it lives. The fact is that, up to the cusp of the K/T Extinction Event, dinosaurs fit extremely well into their ecosystem, with herbivorous dinosaurs dining on lush vegetation and carnivorous dinosaurs dining at leisure on these fattened, slow-witted gourmands. In the blasted landscape left by the meteor impact, small, furry mammals suddenly became "more fit" because of the drastically changed circumstances (and drastically reduced amounts of food).

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Myth - Dinosaurs Went Extinct Because They Became "Too Big"

Was Pleurocoelus "too big" to survive? (Wikimedia Commons).

This one has some truth to it, with an important qualification. The 50-ton titanosaurs living on all the world's continents at the end of the Cretaceous period would have had to eat hundreds of pounds of vegetation every day, putting them at a distinct disadvantage when plants withered and died from lack of sunlight (and also crimping the style of the multi-ton tyrannosaurs that preyed on these titanosaurs). But dinosaurs weren't "punished" by some supernatural force for growing too big, too complacent and too self-satisfied, as some biblically minded moralists continue to claim; in fact, some of the world's biggest dinosaurs, the sauropods, prospered 150 million years ago, a good 85 million years before the K/T Extinction.

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Myth - The K/T Meteor Impact Is Just a Theory, not a Proven Fact

The Barringer Crater is much smaller than the one formed by the K/T Impact (SkyWise).

What makes the K/T Extinction such a powerful scenario is that the idea of a meteor impact was broached (by the physicist Luis Alvarez) based on other strands of physical evidence. In 1980, Alvarez and his research team discovered traces of the rare element iridium--which can be produced by impact events--in geological strata dating to 65 million years ago. Shortly afterward, the outline of a huge meteor crater in the Chicxulub region of Mexico's Yucatan Peninsula was discovered, which geologists dated to the end of the Cretaceous period. This isn't to say that a meteor impact was the sole cause of the dinosaurs' demise (see next slide), but there's no question that this meteor impact did, in fact, happen!

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Myth - Dinosaurs Were Rendered Extinct by Insects/Bacteria/Aliens

A typical caterpillar (Wikimedia Commons).

Conspiracy theorists love to speculate about events that happened millions of years ago--it's not like there are any living witnesses who can contradict their theories, or even much in the way of physical evidence. While it's possible that disease-spreading insects may have hastened the demise of the dinosaurs, after they were already substantially weakened by cold and hunger, no reputable scientist believes that the K/T meteor impact had a lesser effect on dinosaur survival than millions of pesky mosquitoes or new strains of bacteria. As for theories involving aliens, time travel or warps in the space-time continuum, that's grist for Hollywood producers, not serious, working professionals.

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Myth - Humans Can Never Go Extinct the Way the Dinosaurs Did

A chart showing global carbon dioxide levels (Wikimedia Commons).

We Homo sapiens do have one advantage that the dinosaurs lacked: our brains are big enough that we can plan ahead and prepare for worst-case contingencies, if we set our minds to it and muster the political will to take action. Today, top scientists are hatching all sorts of schemes to intercept large meteors before they can plunge to earth and wreak another devastating mass extinction. However, this particular scenario has nothing to do with all the other ways humans can potentially render themselves extinct: nuclear war, genetically engineered viruses or global warming, to name just three. Ironically, if human beings do vanish off the face of the earth, it may be because of, rather than despite, our huge brains!

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Strauss, Bob. "10 Myths About Dinosaur Extinction." ThoughtCo, Jun. 21, 2017, thoughtco.com/myths-about-dinosaur-extinction-1092145. Strauss, Bob. (2017, June 21). 10 Myths About Dinosaur Extinction. Retrieved from https://www.thoughtco.com/myths-about-dinosaur-extinction-1092145 Strauss, Bob. "10 Myths About Dinosaur Extinction." ThoughtCo. https://www.thoughtco.com/myths-about-dinosaur-extinction-1092145 (accessed January 21, 2018).