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There are several theories which were put forward to explain the cause of the extinction of dinosaurs. One of the theories explaining the extinction of dinosaurs is that of cataract blindness. Croft an ophthalmologist studied the role of heat and ultraviolet radiation in causing cataract faster. He proposed that the global warming would have led to an increase in the cataract formation in dinosaurs. He also said that an increased rate may have caused the blindness in dinosaurs before they reached their reproductive stage.

This theory is supported by the fact that placental mammals lack in their eyes a protective oil drop which implies that most of the mammals on the Earth have passed through a nocturnal phase in their course of evolution. Thus, when all the dinosaurs were going blind in the day, the mammals survived because they were nocturnal in their habit and hence took over dinosaurs. This also accounts for why reptiles were saved from becoming blind as they being ectothermic would come out only in the night and thus saved from the effect of global warming and damage to their eyes.

This argument however has some shortfalls as many come up with an argument that if cataract was causing the extinction of species then the selection pressure should have resulted in some structure that would protect the eyes from these harmful radiations. However, the argument as to why Ammonites did not develop cataract is supported by the view that they did not have lens at all and just had a camera like pinhole.

It was said that the cataract blindness caused them to become extinct as they were not able to find food for them and eventually died due to starvation. Somehow, it is a bit weird to imagine monster looking dinosaurs falling off the cliff, tripping over each other and dashing into trees and other things.