Which of the following events has been associated with the extinction of the dinosaurs at the end of the Cretaceous 65 million years ago?

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An outbreak of a highly pathogenic virus occurred, and mammals were apparently immune but reptiles had no defense against it.

An outbreak of global volcanic activity occurred that both directly, through eruption of magma, and indirectly, through ash clouds blocking the sun, caused massive mortality in plants and animals

An asteroid impact caused fires, acid rain, and a massive dust cloud that blocked sunlight for some time, causing rapid global cooling and low plant productivity.

A worldwide change in climate caused by increased carbon dioxide in the atmosphere led to melting of the ice caps and dramatic changes in sea level.

 

asked Dec 28, 2012 in Biology by anonymous
    

1 Answer

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An asteroid impact caused fires, acid rain, and a massive dust cloud that blocked sunlight for some time, causing rapid global cooling and low plant productivity.

 

answered Dec 28, 2012 by anonymous



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