[Taxacom] Selection pressure (Large dicynodont fossil)

John Grehan calabar.john at gmail.com
Sat Nov 24 10:21:50 CST 2018


Ken,

My point was that it was all imaginary. Not science at all. Maybe there
were such selection pressures, maybe there wasn't. It would be like saying
that maybe dicynodonts got bigger because they wanted to. Before they got
so big they obviously survived predation OK or would not have continued
their lineage. Selection pressures can be demonstrated to exist within
populations in the present as an empirical observation. Its another thing
entirely to invoke its role for a historical change in the fossil record
when there is not a shred of evidence either way. Its the stuff that makes
evolution such bad science (or not science at all) and great fodder for
anti-science folk (so far most of them don't realize how bad or they would
have had a field day with this sort of stuff).

John Grehan

On Sat, Nov 24, 2018 at 10:39 AM Kenneth Kinman <kinman at hotmail.com> wrote:

> John,
>        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.
>                               --------------Ken
> ________________________________
> 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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