How were the Dinosaurs killed?

Answer 1

There are many unconfirmed theories as to what caused the mass extinction of the dinosaurs at the end of the Cretaceous Period.

The most widely supported theory suggests that a large meteor struck the Earth approximately 65 million years ago (known as the Chickulub impact), which caused massive amounts of dust and toxic gas to be released into the atmosphere and "block out" the Sun. A lot of dinosaurs died on impact, however most survived to suffer and die later on down the road. Due to less sunlight/energy penetrating the ozone, plants began to die starving the herbivores. As the herbivores died off the omnivores and carnivores lost their food source and began to die as well. Those that survived hunger and starvation eventually died off due to the climate change. Keep in mind that almost all dinosaurs were cold-blooded and therefor relied on the sun for heat and energy. Evidence that supports this theory includes the Chicxulub Crater, which is thought to have been the result of the meteor impact.

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.

Answer2: Listing some speculations as to what happened to them, Princeton scientist G. L. Jepson stated:

"Authors with varying competence have suggested that dinosaurs disappeared because the climate deteriorated . . . or that the diet did. . . . Other writers have put the blame on disease, parasites, . . . changes in the pressure or composition of the atmosphere, poison gases, volcanic dust, excessive oxygen from plants, meteorites, comets, gene pool drainage by little mammalian egg-eaters, . . . cosmic radiation, shift of Earth's rotational poles, floods, continental drift, . . . drainage of swamp and lake environments, sunspots."-The Riddle of the Dinosaur.

It is apparent from such speculation that scientists are not able, with any certainty, to answer the question: What happened to the dinosaurs?

University of Arizona scientist David Jablonski concludes that 'for many plants and animals, extinction was abrupt and somehow special.Mass extinctions are not merely the cumulative effects of gradual dyings. Something unusual happened.' Their arrival was also abrupt. Scientific American observes: "The sudden appearance of both suborders of the pterosaurs without any obvious antecedents is fairly typical of the fossil record." That is also the case with dinosaurs. Their relatively sudden appearance and disappearance contradicts the commonly accepted view of slow evolution.