Why did dinosaurs go extinct?

Question

Why did dinosaurs go extinct?

Answer 1

well, they say that there was a meteor that crashed into earth and that basically screwwed everything up. it changed the atmosphere and they couldnt like... breath anymore lol im not really sure. look it up on Wikipedia.

Answer 2

Mass Extinctions are a time during which extinction rates are generally accelerated so that 50% of all species living become extinct. It is widely believed that so far there have been 5 mass extinctions during the history of the earth!



        The first one happened during the Ordovician period 438 mya (million years ago) The growth of continental glaciers led to the fall in sea levels, changes in oceanic circulation, cooling of the climate and restriction of the tropical belts.

        The second mass extinction happened during the Devonian period 360 mya. This was very severe on the marine creatures, especially warm water and tropical species. It had similar factors of global cooling (Glaciation of Gondwanaland, which was the main land mass on the planet at the time), there has been some evidence that an asteroid was the cause of global cooling which caused either one large or several small extinctions over a period of 3 million years, which is a very short time for half the species on the planet to go extinct!

        The third mass extinction happened during the Permian period 245 mya. This was the largest mass extinction to have occurred wiping out 96% of all marine species and 70% of all vertebrate families suggesting an event that occurred in the ocean. There is much debate as to the cause of these extinctions with theories suggested that there was a sudden glaciation which caused volcanic eruptions, a large meteor struck the earth or poisoning of the oceans.

        The forth mass extinction occurred during the Triassic period 208 mya which led to the extinction of some amphibians, all marine reptiles except ichthyosaurs, and many molluscs. The cause is still in dispute, a possible cause being global cooling associated with an asteroid impact or comet showers. Although it was the least significant mass extinction, losses were very important.

        The fifth and final mass extinction occurred during the cretaceous period 65 mya most famous for being the extinction of the dinosaurs! This mass extinction happened much faster than the others. Nearly 75-80% of all species of life were wiped out over a very short period of time. Dinosaurs, Pterosaurs, Mosasaurs, fish, Brachiopods, plankton and many plants either suffered heavy losses or died out completely.The ammonites which had previously survived 4 other mass extinctions finally disappeared. Some species were almost entirely unaffected such as the crocodiles, turtles, lizards, mammals and birds. This off course led to the rise of the mammals.

Theories as to what led to the extinction of so many species include:

-          Climate Change

-          Volcanic activity

-          Environmental Pollution

-          Increased no. of egg eating mammals

-          Dinosaurs not being able to cope with cooling  atmosphere

-          Dinosaurs allergic to pollen

-          Radiation causing male sterility in dinosaurs

-          And off course the asteroid impact theory



The asteroid impact theory seems to have some evidence to back it up such as high levels of iridium (a rare metal known to occur at impact sites and deep within the earth). Alvarez (1980) proposes that the mass extinction was caused by a 10km asteroid.Another theory suggests that global cooling followed by greenhouse warming (due to CO2 released by a massive eruption of larva) placed enormous stress on the dinosaurs. Keller et al (2004) predicts that there was an asteroid impact during the warming period but a second impact hit the earth 300,000 years later which finished of the creatures.



During most mass extinctions, only 15-30 species became extinct each year, most mass extinction events takes hundreds of thousands of years which appears instantaneous in geological time.  After each mass extinction came a huge increase in the diversity of life thanks to the sudden availability of new niches and resources for the surviving species.

Answer 3

I believe a combination of two theories.  

The meteor killed off most of the bigger dinosaurs, and the remaining small ones evolved to become the birds of today.

Answer 4

This answer is not in keeping with the popular theories taught in state universities and public schools.  However, another theory is that the Genesis flood wiped most of them out the rest of them died off later, because they were giant, cold-blooded reptiles and could not adapt to the changing climates on earth after the universal flood.

Answer 5

The overwhelmingly predominant theory is that a huge impact, probably from a meteor occurred near the end of the Cretatious period. The impact would have killed everything for hundreds of miles, and blacked out the sun for decades. Only insects, water-dwellers, and very small animals that could live on the meager resources available could survive.

Answer 6

current theory is that an asteroid hit the earth roughly 65 million years ago in the Yucatan penninsula. This event sent a lot of dust in the atmosphere, decreasing the amount of sunlight that reaches the earth, killing of most plant life and creating a chain reaction in the food chain killing off about 2/3 of all species on earth.