From this brief exploration of the issue I would say that it is fair to say that they know neither why the dinosaurs die off nor the amount of time it took for them to die off. Each of these so called scientists are so firm in their interpretation of the evidence that can study. All we truly know about dinosaurs are the few relatively bones found, and the type of earth that they were found in, everything else is speculation. Here are the different reason put forth for the dinosaurs die off and how fast they died off:
The extinction 200 million years ago, at the boundary between the Triassic and Jurassic periods, killed the last of the mammal-like reptiles that once roamed the Earth and left mainly dinosaurs, Ward said. That extinction happened in less than 10,000 years, in the blink of an eye, geologically speaking.
Dinosaurs Died Within Hours After Asteroid Hit Earth
According to new research led by a University of Colorado at Boulder geophysicist, a giant asteroid that hit the coast of Mexico 65 million years ago probably incinerated all the large dinosaurs that were alive at the time in only a few hours, and only those organisms already sheltered in burrows or in water were left alive.
The Permian Mass Extinction was not Instantaneous, but was Still Sudden, Geologically: The National Science Foundation (NSF) reports research showing the deadliest mass extinction of all—“The Great Dying” or the Permian-Triassic extinction 252 million years ago at the end of the Permian period, which killed 90 percent of Earth’s marine life—took a long time to do it, and it did it in stages. So, mass extinctions need not be “sudden” events. Thomas Algeo, a geologist at the University of Cincinnati, and 13 colleagues have produced a high-resolution look at the geology of a Permian-Triassic boundary section at Griesbach Creek on Ellesmere Island in the Canadian Arctic. They offer strong evidence that Earth’s biggest mass extinction phased in over hundreds of thousands of years.
Why did the dinosaurs disappear? New evidence
Most dinosaurs were already under gradual extinction long before a large asteroid fell to Earth about 65 million years ago which became the final blow for them. This conclusion was reached by a new US-German research, shedding more light on one of the biggest enigmas in the history of the world,the extinction of the dinosaurs, a landmark event that paved the way for the prevalence of most mammals and eventually of human. The new study shows that ultimately the extinction of the dinosaurs was not a single, brief event.
Dinosaurs were wiped out by sudden drop in temperatures, not by comet striking the planet, scientists claimed.
Volcanoes, Not Meteorite, Killed Dinosaurs, New Study Suggests
Dinosaurs may not have been killed off by asteroid impact dust blocking out sunlight, a geologist says. Instead, the mass extinction associated with an asteroid impact 65 million years ago might have been caused by soot from global wildfires or sulfuric acid clouds that were a consequence of the collision.
What Killed The Dinosaurs?
Two main camps exist in paleontology today, each having a different view of what killed the dinosaurs and other organisms at the K-T boundary. Controversy has surrounded the topic since 1980; it has become difficult for the public (and the scientific world at large) to understand the issue due to the tangled assemblage of data which seems to point in many different directions. Luckily, the controversy has not harmed the study of mass extinction causation, but rather has made it a dynamic and interesting area. Every groundbreaking new hypothesis makes new headlines in the media, and excites researchers to delve further into the mystery. The major sides of the schism can be broken down (greatly simplifying the issue, but making it more accessible) into “intrinsic gradualists” and “extrinsic catastrophists.” We’ll describe each generalized group in turn, and then try to synthesize the available information so you can form your own opinion. But first, let’s outline what scientists generally agree that we know about the K-T boundary.
What killed the dinosaurs? Their sudden disappearance 65 million years ago, along with at least 50 percent of all species then living on Earth, is known as the K-T event (Cretaceous-Tertiary Mass Extinction event). Many geologists and paleontologists now think that a large asteroid or comet impacting the Earth must have caused a global catastrophe that led to this extensive loss of life. The Chicxulub crater in the Yucatan region of Mexico is a good candidate for the ancient point of impact. The crater is the right age – 65 million years old – and it is consistent with the impact of a 6- to 12-mile-wide asteroid. The asteroid would have to have been at least that large to cause global disruptions.
And lastly from a September Headline:
Meteorite crater in Brazil reveals biggest extinction in Earth history
Tue, 03 Sep 2013 15:15 CDTPrint
Perth, Australia – It’s well known that the dinosaurs were wiped out 66 million years ago when a meteor hit what is now southern Mexico but evidence is accumulating that the biggest extinction of all, 252.3m years ago, at the end of the Permian period, was also triggered by an impact that changed the climate.