From: CurtAdams@aol.com
Date: Tue Jun 26 2001 - 12:52:13 MDT
In a message dated 6/26/01 10:38:34 AM, neptune@mars.superlink.net writes:
>> The above groups all differ from dinos in that they
>> can take refuge underground or underwater*.
>
>What of smaller dinos?
Not so much a size issue; mammals often burrow and shorebirds dive. I'm not
aware of any dinos that did either.
>> If the
>> earth was put on "bake" for 1 day, as one estimate of
>> tecktite heat delivery has it, the dinos would indeed
>> be all gone and the above groups still there.
>Archibald does cover this in _Dinosaur Extinction and the End of an Era_.
Well, what does he say? This would indicate a bolide was well capable of the
land extinctions of the end-Cretaceous, all by itself.
>> An interesting point is that the end-
>> Cretaceous and end-Permian extinction match up with
>> *both* massive bolide impacts *and* bogglingly large
>> flood basalts.
>Yeap. Archibald does not dispute this, though there is some disagreement
>over timing. On page 145 of the book, he even charts the level of eruption,
>but argues on 144 that the "eruptions... were episodic -- not continuous."
>The flood basalts range in age from 69 to 65 million years old. If the
>impact is placed at 65 million years ago, this means a good portion of high
>level volcanic activity was already happening before the impact. This does
>not completely rule out an impact as the [nonavian] dinosaur killer, though
>it might point to an accomplice.
It's more than an accomplice for the end-Cretaceous. There are dino
fossil beds in N. America that run right up to the iridium layer without
detectable extinctions and then - whammo - nothing. For that extinction,
the bolide is the main player and flood basalts/ climate change the
accomplice or bystander. The end-Permian buckyball layer is too
recently found for such study. The end-Cretaceous and end-Permian
extinctions differ in that the e-C hit land creatures harder and the
e-P hit sea creatures harder (although it was ferocious for everything).
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