Why did stegosaurus died?

There are many theories as to why the stegosaurus (and indeed, all the dinosaurs) went extinct. The current prevailing theory is that a meteor hit the Earth and caused large amounts of CO2 to clog the atmosphere causing an ice age which was too cold for the cold-blooded reptiles.

Answer2: That dinosaurs existed abundantly throughout the earth, in an ancient landscape long ago vanished, is obvious from the fossil record. But these amazing creatures, along with countless other animal and plant kinds, passed out of existence. As to just when these things took place, paleontologist D. A. Russell states: "Unfortunately, existing methods for measuring the duration of events that happened so long ago are relatively imprecise."Fossil record does not yield its secrets so easily and that no one on earth today really knows all the answers.

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.