Re: EARLY EVOLUTION OF 'BIRDS'

["John V Jackson" <jjackson@interalpha.co.uk>]

--Original Message-- From: Stewart, Dwight <Dwight.Stewart@VLSI.com>Date: 07
November 1998 00:30


>All things being equal, 9 heads or tails in a row
>CAN occur, but will be rare.  Sampling is the issue & with fossilization it
>seems that sampling is skewed automatically.

But how come the skew is one way for J pterosaurs and the other for "J
maniraptora"?

>the point is that statistics can be very
>skewed or even rendered inaccurate by sampling.  This is complicated by
>interstitual or matrix inbedded chaos.  No matter how ordered a system is,
>there is always an element of chaos inbedded within the structure.

There are few systems so chaotic that stats can't be applied.


>The reverse is also true.  In a complex system, which all biological sytems
are,
>there are numerous
> Elements of chaos (or unpredictability) within the structure.
> One element would be variation in animal behavior.  The point being
>that a sampling population could seen intuitively robust, but in fact be
>seriously skewed to produce one outcome or another.
>
> Dwight

Skews are just more material for a statistician to work on.  Skew is even a
formally defined statistical entity.  It seems very strange to me though
that small pterosaurs can be preserved and found by the dozen but 20k+
theropods either didn't preserve well or weren't so easily noticed.  There
just possibly *might* be some very wierd process hiding those "J mani's" but
if you have to assume something, it's best to assume something 99% likely
rather than the 1% alternative.

JJ