Research Article

On impact and volcanism across the Cretaceous-Paleogene boundary

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Science  17 Jan 2020:
Vol. 367, Issue 6475, pp. 266-272
DOI: 10.1126/science.aay5055

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  • RE: Why the dinosaurs died and the mammals flourished

    The reason all of the dinosaurs and birds with teeth died, and the mammals survived and flourished, is because the worldwide environment that favored the dinosaurs and birds with teeth changed, and the mammals were already adapted to the new environment.

    The only part of the environment that is present all over the world is the atmosphere.

    Mammals and dinosaurs coexisted for tens of millions of years. What could be the fundamental difference between them?

    The evolution of birds without teeth might provide a hint of the answer. If we think of why this might occur, we could hypothesize that birds without teeth might be able to fly higher in thinner air.

    Here we have to make a leap and think of the time before the meteor impact as a time when the atmosphere was much thicker, with a much higher concentration of oxygen. Scientists at the University of Arizona say this is so.

    In that atmosphere, dinosaurs evoled to take advantage of, and also depend on,, the higher concentration of oxygen.

    This atmosphere would also create a climate that was warmer, with much less of a change between day and night temperatures.

    Now we see mammals who have a set of adaptations that take advantage of an environment with more extreme temperature changes. Live birth, lactation, warmbloodedness, and hair all combine to protext and animal that deals with cold weather and temperature changes.

    The only place in the ancient world where this could...

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    Competing Interests: None declared.

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