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Re: The Permian-Triassic Extinction



Dora Smith wrote:

I understood that the shutting down of the ocean currents only became possible as the planets assumed their current positions, around the end of the Cretaceous era, or later.

I was a little confused, and I thought there was some astrological allusions here. But I guess you meant "continents" rather than "planets". :-)


The shutting down of ocean circulation causes an ice age, not global warming.

I'm not sure if I'm responding with another non sequitur, but with the continents jammed together to form one giant landmass (Pangaea), the terrestrial biotas were exposed to harsher, drier environments that resulted from a drastic decrease in the ratio of coastline to the vast interior.


A sudden drop in global temperature followed by global warming is usually attributed to the Siberian Traps. The bolide hypothesis does not have much support when it comes to the Permian/Triassic extinction.

The notion that that in turn causes ocean organisms to make hydrogen sulfide is the original non sequitor. What kind of common organisms even make that amount of hydrogen sulfide,

Lots and lots of microbes do this. I've worked with a few. Stinky.

Is there any evidence that all dinosaurs from the end of the Permian time had modern birdlike lungs?

No Permian dinosaurs (as others have pointed out, with admirable restraint). There were dinosaurian ancestors back then, in the form of basal archosauromorphs (and maybe archosauriforms).


If something wiped out most life on earth tomorrow, it might be hard for creatures 125 million years from now to believe how highly evolved life was when that happened. There might be no primates around to tell the tale. Just talking birds.

These talking birds might even take little mammals in cages down into their mines.


Cheers

Tim

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