What killed off the dinosaurs?

Answer 1

A current theory that is widely accepted and supported by a great deal of evidence is that organisms were significantly affected by the environmental effects of the Chicxulub meteor impact, leading to the disruption of the food chain and the extinction of nearly 60% of the existing species that existed at that time including the non avian dinosaurs.

Essentially, the atmospheric dust and gas created prevented the Earth's plants from receiving enough sunlight over a period of many years. The colder climate also reduced the habitats of cold-blooded reptiles like the dinosaurs.

Another event that is thought to have contributed to this mass extinction is the occurrence of very large scale volcanic eruptions (known as a large igneous province) in this case known as the Deccan Traps that produced significant volumes of volcanic gasses that contributed to global cooling.

Dinosaurs were a casualty of one, or a combination of, these events.
it is a metor rock that crushes into the earth kill the dinosaurs

Answer 2

Scientists have many theories about what caused the extinction of dinosaurs. Below are thoughts on some of the most common theories:

• Since about 90% of dinosaurs were herbivores (plant eaters), it was thought that when an asteroid hit earth and many tons of dust was thrown into the atmosphere that the result was a "long night" due to the lack of sunlight that was able to reach earth, the plants died out and without a food source, so did the dinosaurs.

• It could also have been the combination of the Chicxulub asteroid impact event (causing worldwide fires and environmental catastrophe in association with the Deccan Traps volcanic event, which occurred at around the same time, or possibly as a result of, the asteroid impact event.

• There are many theories that are written throughout history of why the dinosaurs exactly were driven into extinction. Most are meteor impact related. By looking at craters all over the world, scientists can estimate the meteors size, speed and its impacts effect on the local environment. See the related link for more information.

• Though the large meteorite impact (Chicxulub) figures prominently in a lot of the theories of how the dinosaurs became extinct, the idea of a gamma ray burst has also come up now that we are aware of them and the threat they pose. Additionally, there was an "outburst" of volcanic activity during this period. This extinction event is at the Cretaceous-Tertiary (K-T) boundary.

• It should also be added that several other large impact events occurred right about the time of Chicxulub, including Silverpit and Boltysh craters, among others. It seems the deck was "stacked against" the dinosaurs, regardless of how you look at it. It is possible that things are "found" to "corroborate" extinction by space rock, but the facts are pretty convincing, even for the skeptic.

• It was noted but is worth repeating: many of the ideas that represent credible ways that could have triggered the dinosaurs' extinction could have arisen separately and acted in concert to kill off all these creatures. One thing is certain - they're gone. And the demise of the terrible lizards was caused by something dramatic given the relatively narrow window in which they disappeared.

• The hypothesis that states an asteroid-impact was the sole cause of the extinction is just that - an hypothesis, not a fact. Most paleontologists feel that the asteroid impact was just one of a series of catastrophic events that ultimately wiped out the dinosaurs. There is evidence of a huge meteor strike just off the Yucatan Peninsula, true. And a meteor may well have put a final period to the extinction pulse. But there is also evidence that other factors may have been involved. For one thing, the dinosaurs didn't become extinct all at once. The pulse seems to have taken more than 10-thousand years to complete which makes the asteroid theory implausible as a complete explanation. There is evidence that there was massive volcanic activity also, and a drastic climatic change. The dinosaurs were in decline in number of species long before the K/T extinction was over. Furthermore, some dinosaurs did survive into Laramide time - the birds are still around (admittedly that's begging the issue, but it's not unreasonable to ask how they managed to survive when so many their brethren were killed).

• Dinosaurs were already fast becoming endangered species before the Chicxulub impact. Increased volcanic activity such as the Deccan Traps in modern day India was slowly killing many species. Between 68 to 60 million years ago 150,000 km2 of igneous rock was deposited in places more than 2 km thick. The bulk of the eruptions occurred about 66 million years ago near modern day Mumbai. These eruptions lasted as little as 33,000 years but the effect on the environment would have been staggering. Dust and debris thrown into the atmosphere along with sulphur dioxide would have cooled the earth. Also many poisonous gases would also have been released. Studies on modern day birds suggest that these poisonous gases not only directly killed dinosaurs but also caused thinning of the shells of their eggs which meant that many would fail to hatch.

• It has also been suggested that disease killed off the dinosaurs. A very deadly and contagious disease may have circulated among the dinosaurs forcing them to become extinct. Still yet another theory is that the Earth just gradually changed in climate over a long time period and the dinosaurs were not able to adapt to the cooler, dryer climate.

Answer 3

There is a widely believed theory developed in the 1980's that it was a massive meteor that penetrated the atmosphere. How do we know? In the Gulf of Mexico, there is a very large hole with mass deposits of Iridium, a periodic element that is the chief composition of meteorites. The date of the deposits of the iridium dates back to around the time the dinosaurs were wiped out. Its size and concentrations of iridium suggests that at the right speed, the pressure of a collision could have thrown up enough debris and smoke in the atmosphere bringing on a severe global cooling that caused the extinction of the dinosaurs.

Answer 4

probably a combination of asteroid, volcano and the lack of plants to eat

Answer 5

an object from space struck earth