Theories on Dinosaur Extinction Essay

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Theories on Dinosaur Extinction

What killed the dinosaurs? Several theories have been brought up over time to answer this question. It has been of vast interest to many scientists how creatures the size of the dinosaurs could have been wiped out of existence.

Proposed Theories

Climate Change Theory Some scientists propose that climate change was killing the dinosaurs before the famous asteroid struck. Fossil evidence shows that the average temperature had dropped from 25 degrees Celsius to 15 degrees Celsius and that the amount of annual rainfall had decreased. Fossil evidence also shows that more than half of the dinosaurs (many large plant-eating dinosaurs), crocodiles, and turtles of the time were gone before the
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The sulphate, combined with water from the atmosphere, would have formed sulphuric acid clouds. These clouds would have covered the earth blocking the sun. This would have caused global cooling and a shut-down of photosynthesis. The cloud is said to have lasted between 6-10 years causing the dinosaurs to die of hunger.

Evidence for this theory is in sediments of layers of clay that are rich in iridium that have been found around the world. The iridium in the clay would have been a result of a collision of an asteroid with the earth. More evidence was found in 1983 when a crater that appeared to be as old as the iridium- rich clay was found in Mexico.

Buck Sharpton Buck Sharpton from the University of Alaska believes that the supposed cloud caused by the asteroid could not account for the extinction of the entire planet. His hypothesis is that the asteroid impact may have caused poisonous sulphur dioxide and carbon gases that, along with the dust from the cloud, choked the dinosaurs to death.

Sudden Methane Explosion Gregory Ryskin of Northwestern University believes that methane is reason that the dinosaurs perished. He believes that a cloud of methane gas was erupted from the ocean causing catastrophic floods and fires which killed off the dinosaurs. His evidence is fossils that show a rise in carbon-12 isotopes.

However, skeptics of

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