We all know that the dinosaurs mysteriously (or not so mysteriously) vanished off the face of the earth about 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 close cousins, the pterosaurs and aquatic reptiles? The details are still being worked out by geologists and paleontologists, but in the meantime, here are ten beliefs about dinosaur extinction that aren't quite true.
1. All the dinosaurs died quickly, at the exact same time.
According to our best knowledge, the K/T (Cretaceous/Tertiary) Extinction was caused by a meteor that plunged into the Yucatan Peninsula in Mexico 65 million years ago. However, this doesn't mean that all the world's dinosaurs suffered an instant, fiery death. 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.
2. Dinosaurs were the only creatures that went extinct 65 million years ago.
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, while numerous species of mammals, birds, plants and invertebrates were wiped off the face of the earth, enough other species survived to repopulate the land and sea afterward. The dinosaurs, pterosaurs and aquatic reptiles weren't so lucky; they were exterminated down to the last species (and not only because of the meteor impact, as we'll see below).
3. Dinosaurs were victims of the first-ever mass extinction.
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 70 percent of terrestrial animal species and more than 95 percent of ocean-dwelling species. 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 very first dinosaurs.
4. Until they went extinct, dinosaurs were thriving.
You can't make the case that dinosaurs were on top of their game when they bit the Big Cretaceous Weenie. According to a recent analysis, dinosaur radiation (the process by which species adapt to new ecological niches) had slowed down markedly by the middle of the Cretaceous period, with the result that dinosaurs were far less diversified at the time of the K/T Extinction than birds, mammals, or even amphibians. This may help to explain why the dinosaurs went completely extinct, while various species of birds, mammals, etc. managed to survive into the Tertiary period.
5. Some dinosaurs have survived down to the present day.
It's impossible to prove a negative, so we'll never know, with 100 percent certainty, that absolutely no dinosaurs escaped the K/T extinction. However, the fact that no dinosaur fossils have been found dating from later than 65 million years ago--combined with the fact that no one has yet encountered a living T. Rex or Velociraptor--is solid evidence that the dinosaurs did, indeed, go completely kaput. If you want to get technical about it, though, we do know that birds are directly descended from dinosaurs, so the continued survival of pigeons, penguins and puffins may be some small consolation.
Next Page: Dinosaur Extinction Myths 5-10
