Dinosaurios

Did Dinosaurs bake to death?
A case of Too Much Sun
Geologist Walter Alvarez and his Physicist father, Luis, galvanize the world of science in 1980 by arguing that a meteor had smashed into theearth 65 million years ago, killing off the dinosaurs and uncounted millions of other beastes. Since they floated their theory, researchers have busied themselves trying to figure out how the meteormight have exacted its toll. One explanation holds that its impacted lofted a global dust cloud inte the air, shutting out life-giving sunlight. Another idea is that the collision touched off a worldwidedownpour of acid rain, killing plants and eventually the animals that ate them. Now, in the current issue of the british Journal Nature, two researches suggest that the doomed species were, well, sortof baked to death.
The nw theory, by Michael Rapino and Tyler Volk, of New York University (NYU), is a model of deductive reasoning, They knew that the chemical dimethyl sulphide (DMS) is nature'scloud maker, serving as the nuclei around which water droplets condense in the air and form clouds. They also knew that marine algae are the chief source of DMS. Fossil records show that some 95 percent of the algae disappeared jus about when the dinosaurs did, perhaps because an arriving meteor enveloped the Earth in dust. With few algae left, clous would have been as rare as brontosaurusesare today. The NYU team calculates that the clear skies would have been hot skies: without clouds to reflect the sun's rays back into space, global temperatures would have risen about 11 degreesFahrenheit. According to this reappraisal, then, the dust cloud did not kill the dinosaurs by blocking sunlight, but by allowing too much in.

"Many animals live close to their maximum tolerabletemperature already", note Rampino. Any extra heat could do them in. Only creatures lucky enough to have a built-in heat tolerance would survive, most id not come so equipped, and 75 per cent of the species...