Why did all dinosaurs go extinct?

1 Answer
Nov 11, 2016

The extinction of dinosaurs or the Cretaceous - Paleogene extinction event was a mass extinction of 75% of the plant and animal species on Earth, over a geologically short period of time.


With the extinction of some ectothermic species , no tetrapods weighing more than 55pounds survived. It marked the end of the Cretaceous period, the entire Mesozoic era, opening the Cenozoic era that continues today.

This event is marked by a thin layer of sediment which can be found through out the world in marine and terrestrial rocks. It shows high level of iridium which is rare in the earths crust but abundant in asteroids.
It is thus thought that the extinction was triggered by a massive comet or asteroid impact.

It had catastrophic effects on global environment including a lingering impact winter that made it impossible for plants and planktons to carry out photosynthesis.

Since there is no evidence that the non avian dinosaurs could swim, burrow or dive, they were unable to shelter themselves from the worst parts of any environmental stress that occurred during the extinction.

It is possible that smaller dinosaurs survived , but they would have been deprived of food , as herbivorous dinosaurs would have found plant material scarce and carnivores would have quickly found prey in short supply.

Thus under the circumstances of food chain disruption non avian dinosaurs died.

However some scientists maintain the extinction was caused by other factors, such as volcanic eruptions , climatic change , or sea level change separately or together.