How did Dinosaurs Just Disappear?

Answer 1

The sudden mass extinction of the non-avian dinosaurs, which occurred around 65 million years ago, is one of the most intriguing mysteries in paleontology. Many other groups of animals also became extinct at this time, including ammonites (nautilus-like mollusks), mosasaurs, plesiosaurs, pterosaurs, herbivorous turtles and crocodiles, most birds, and many groups of mammals.[32] The nature of the event that caused this mass extinction has been extensively studied since the 1970s. At present, several related theories are broadly supported by paleontologists.

Asteroid collision

The Chicxulub Crater at the tip of the Yucatán Peninsula, the impact of which may have caused the dinosaur extinction.The asteroid collision theory, which was first proposed by Walter Alvarez in the late 1970s, links the extinction event at the end of the Cretaceous period to a bolide impact approximately 65.5 million years ago. Alvarez proposed that a sudden increase in iridium levels, recorded around the world in the period's rock stratum, was direct evidence of the impact. The bulk of the evidence now suggests that a 10 km wide bolide hit in the vicinity of the Yucatán Peninsula, creating the 170 km-wide Chicxulub Crater and triggering the mass extinction. Scientists are not certain whether dinosaurs were thriving or declining before the impact event. Some scientists propose that the meteorite caused a long and unnatural drop in Earth's atmospheric temperature, while others claim that it would have instead created an unusual heat wave.

Although the speed of extinction cannot be deduced from the fossil record alone, various models suggest that the extinction was extremely rapid. The consensus among scientists who support this theory is that the impact caused extinctions both directly (by heat from the meteorite impact) and also indirectly (via a worldwide cooling brought about when matter ejected from the impact crater reflected thermal radiation from the sun).


Multiple collisions—the Oort cloud
While similar to Alvarez's impact theory (which involved a single asteroid or comet), this theory proposes that a stream of comets was dislodged from the Oort cloud due to the gravitational disruption caused by a passing star. One or more of these objects then collided with the Earth at approximately the same time, causing the worldwide extinction. As with the impact of a single asteroid, the end result of this comet bombardment would have been a sudden drop in global temperatures, followed by a protracted cool period.[33]

Environment changes
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. [34][35]

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.[32]

http://en.wikipedia.org/wiki/Dinosaur

Answer 2

There are many different thoughts about it but the most popular is that a meteorite has fallen on Earth, so a lot of animals including dinosaurs have disappeared

Answer 3

you should read Dean Koontz's Phantoms, if you wanna know how the dinosaurs, and lots of other things, really disappeared...trust me, its worth it. a lot better than the movie too

Answer 4

It was just like you see on TV.

The didn't listen to their mothers. When the stranger in a car came along looking for his "lost puppy," they just wanted to help, got in the car, and nobody's seen them since.

Answer 5

lots of people say thet earth grew cooler or a meteor that sruck earth

Answer 6

They didn’t. Al Gore’s great, great, great, great, great, great, great, great, great, great, great, great Grandfather was preaching about Global Warming, so they all migrated to Antartica where they are hibernating until the earth is safe for them again.

Answer 7

They haven't. Look around! You'll see them! They just aren't as big as they used to be.

Answer 8

i told them to go

Answer 9

coz we came ............