Comet's Tale: Killer Comets
Did Comets kill the Dinosaurs?
Maybe, maybe not. This is a matter of some controversy in the scientific community. There are two main hypotheses. The "Extrinsic Catastrophist" and the "Intrinsic Gradualist."

New research suggests that the truth may be found in some combination of these two schools of thought.

Dinosaur to Skeleton:  "What, me worry?"

"What,me worry?"


As a group, scientists seem to agree:

POINT #1: There is evidence that the Earth went through a permanent global climatic change 65 million years ago.

POINT #2: As well as a permanent global climatic change, there is evidence that there were temporary environmental changes that may have been the result of a massive terrestrial disturbance. Such a disturbance threw up soot and dust into the air causing short term acid rain, emission of poisonous gases, and cooling.

POINT #3: Many life forms besides the dinosaurs - both vertebrate and invertebrate marine and terrestrial organisms - went extinct. The reason for this extinction was probably the global and permanent climatic change.

POINT #4: At or near the 65 million year old geological boundary in several places around the globe, scientists have found a thin layer of clay with an unusually high iridium content.

Scientists agree that the above points are valid,, but disagree about what caused their existence and the extinction of the dinosaurs and other life forms. Thus, we have a scientific CONTROVERSY.


Many thanks to: John R. Hutchinson at the Department of Integrative Biology University of California - Berkeley for considerable contribution to this "Killer Comets" section.



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