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the warmer the earth’s surface and climate.
Carbon Dioxide Factor
McLean believes this “greenhouse effect” caused the oceans to become warm* er. Warmer water released more dissolved carbon dioxide, creating a chain reaction of warming conditions.
McLean says temperatures during the age of dinosaurs were warmer than they are today, marked by gradual cooling and warming trends. The extinctions occurred when a period of gradual cooling was interrupted by abrupt warming.
Even then, he says it is unlikely temperatures increased more than a few degrees, because there were no widespread extinctions in the plant kingdom.
McLean’s is the latest of numerous theories on the extinction of dinosaurs. One early idea was that the creatures became so large that they had difficulty in mating.
A more recent theory holds that the dinosaurs died because of a shower of radiation from an exploding si ar.
Another view was that the spread of flowering plants subjected the big reptiles to an onslaught of pollen, which led to respiratory problems.
+++ A retentive memory is a good thing, but the ability to forget is the true token of greatness.
—Hubbard
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