There are dozens of theories to explain a probable cause or causes. Throughout the Mesozoic Era, individual dinosaur species were evolving and becoming extinct for various reasons. The unusually massive extinction at the end of the Cretaceous exterminated the last of the dinosaurs, the flying reptiles, and the large swimming reptiles, as well as many other marine animals. There is now widespread evidence that a meteorite impact was at least the partial cause for this extinction. Impact craters are visible on most planets in our solar system. A spectacular example of this was witnessed in 1994, when Jupiter was struck by a series of cometary fragments. Some of these impact blasts were larger than the Earth's diameter. Other factors such as extensive release of volcanic gases, climatic cooling (with related changes in ocean currents and weather patterns), sea-level change, low reproduction rates, poison gases from a comet, or changes in the Earth's orbit or magnetic field may have contributed to this extinction event.
|When did dinosaurs become extinct?||Dinosaurs: Fact and Fiction|