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Re: Viva Neornithine Birds!
----- Original Message -----
From: "john bois" <firstname.lastname@example.org>
Sent: Monday, February 05, 2007 10:42 PM
David M. said:
If ten clades survived, that means ten breeding pairs must have survived.
Twenty birds in the whole world is still not what I'd call "mass
survival" or use to argue against the size of the impact. 100 or 1000
worldwide would still not be "mass survival".
Disagree. A ten to zero neo vs. enanti victory _suggests_ mass survival.
I mean, lone survival infers sheer luck. But if ten lone couples survived
for luck reasons, the chances are none that they would all be
When ten couples out of billions and billions survive, anything can happen.
Of course, not all species are equally susceptible to the various effects of
impacts, and I think this is what we are looking at here. Arboreal birds
will run into trouble when all the trees burn, for example. This --
exaptation for impact conditions -- seems to be what you have never taken
into account so far.
Assuming equal numbers and distribution of neornithines and
enantiornithines, the probability is .5 ^10 that they would _all_ be
How do you arrive at this number?
Well, (the "shorebird" hypothesis) was wrong.
Can I quote you as an authority?
No. Instead, quote... IIRC... _any_ cladistic analysis of Neornithes,
including the latest one. (Feduccia has never done one.)
That is a misrepresentation. Given that huge crater, what do we expect,
and do we find those expectations confirmed? So far we find many of
them confirmed, and haven't managed yet to disprove any.
It's glib because it doesn't require evidence and is, indeed, untestable.
What? It requires evidence for an impact. It is entirely falsifiable: show
me that the -- more and more precise -- expectations are _not_ met, and the
hypothesis that the impact alone is to blame _is_ disproven. For example,
show me a steady decline of Enantiornithes across the boundary, or one that
reaches 0 right at or even before the boundary, at the same time an increase
in neornithine diversity, and show that whatever environmental conditions
can't be to blame (that's the easiest part).
It's glib because luck could be said to be involved in all extinctions or
none depending on how you define it.
We're not talking about the presence of luck, we're talking about the
absence of competition...
And it's glib because it inspires glib
hypotheses (e.g., the fanciful crab-cracking of shore birds).
Never heard of that one.
arguments from authority are unscientific;
Unless one knows everything about everything, it is helpful to rely on the
wisdom of others.
Then quote their work, not their sayers. They, too, must show that their
hypotheses are falsifiable and so far unfalsified, and generally they do.
...secondly, Livezey & Zusi are not even authorities on molecular
phylogenetics or divergence dating in the first place.
True. They were attractive to me because they don't seem to have a vested
interest in interpreting molecular data--and yet they need to have a
thorough knowledge of the literature. But, say...are you arguing against
their conclusions, or just gainsaying for epistemological sport?
You still haven't understood them. That particular claim is _not_ part of
their conclusions. It is part of the introduction of their paper: they give
a general overview of the subject, talking about the work of others and
presenting _their_ conclusions without evaluating them. The data matrix and
the tree of Livezey & Zusi don't have anything to do with this
"conclusion" -- _and they never claim they do_.