[Taxacom] Selection pressure (Large dicynodont fossil)

Kenneth Kinman kinman at hotmail.com
Sat Nov 24 09:39:13 CST 2018

       Yet another "fairy tale" complaint?  I'm not sure if your complaint is about the word "selection" or the word "pressure" or the word combination.
        As for the large dicynodont, selection would not only have protected them from their predators getting larger (survival selection).  It may have also been the result of bigger males having more offspring (reproductive selection), either due to males fighting for females (or possibly females choosing bigger males as mates).
        This positive selection for larger size worked very well during the good times.  But when the end-Triassic extinction event came along negative selection would have been particularly hard on the larger animals.  Volcanism and the resulting climate change could have easily resulted in starvation (and perhaps increased disease) in many taxa.
From: Taxacom <taxacom-bounces at mailman.nhm.ku.edu> on behalf of John Grehan <calabar.john at gmail.com>
Sent: Thursday, November 22, 2018 6:22 PM
To: taxacom
Subject: [Taxacom] Large dicynodont fossil

So they found a large herbiroous dicynodont fossil that walked in an
upright manner, similar to large mammals like rhinos and hippos that lived
between 210 and 205.

So to the question of why it was so large it was said " Researchers believe
selection pressures—potentially to protect themselves from larger
predators—may have been the driver behind their giant size"

Good grief. Why is something so large? - selection pressure. Why is
something so small? - selection pressure. Why is something in between? -
selection pressure. Why do we have to rest science on such fairly tales? -
selection pressure. What would we do without selection pressure? What would
we do?

John Grehan

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