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Re: Viva Neornithine Birds!

David said:
> Of course, not all species are equally susceptible to the various effects
> 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.

Not at all.  All I want are hypotheses for why neornithines.  Previously,
this request was resisted on grounds that extant bird diversity descended
from a single surviving species.  Under this conceptual regime, it made
sense to invoke luck.  However, with more surviving species it is sensible
to delve a little deeper.  Your hypothetical example of  arboreal species
suffering higher extinction rates might be testable...at least it is an
attempt to _explain_.

> > Assuming equal numbers and distribution of neornithines and
> > enantiornithines, the probability is .5 ^10 that they would _all_ be
> > neornithines.
> How do you arrive at this number?

For Neo/Enanti pair #1, chance of Neo surviving and not enanti is .5.  Same
with pairs 2 through 10.  Multiply unrelated outcomes for astronomically
small chance of only neos surviving.

> > It's glib because it doesn't require evidence and is, indeed,
> What? It requires evidence for an impact. It is entirely falsifiable: show
> me that the -- more and more precise -- expectations are _not_ met, and
> hypothesis that the impact alone is to blame _is_ disproven. For example,
> show me a steady decline of Enantiornithes across the boundary, or one
> reaches 0 right at or even before the boundary, at the same time an
> in neornithine diversity, and show that whatever environmental conditions
> can't be to blame (that's the easiest part).

Two things: 1. Evidence of an impact and mass extinction is not necessarily
evidence for differential survival of neos vs. enantis--unless you can
propose a testable hypothesis for why.  The tyranny of this
bolide-explains-everything is weakened by increased survival and especially,
differential survival of similar species!
2. I agree that hypotheses regarding enanti/neo temporal and geographic
distribution need testing.  And then let ideas follow the data.  Enough of
this umbrella hypothesis.

> > And it's glib because it inspires glib
> > hypotheses (e.g., the fanciful crab-cracking of shore birds).
> Never heard of that one.

Feduccia's idea: detritus-eating crabs survive due to abundance of food
remaining; shore birds eat crabs and survive.

> > ...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.

 I am not not not claiming that pre-boundary neo survival was an official
Conclusion of this paper.  But, in this informal venue, I believe it is OK
to say that, after a review of the relevant literature, they concluded the
following: "If accurate, despite the vulnerability of such data to
suboptimal rooting, this record undermines early anticipations of K-T
boundary effects in modern orders and an evolutionary timespan in which
major divergences of neornithine lineages would extend through the early and
middle Cenozoic."
I agree that I should have been more careful in my initial post: I should
have said they were reviewing other literature and that the data referred to
was not fossil but molecular data.  I certainly was not trying to mislead.
Let's move on.
Are you arguing against the conclusions of the references they cite?
Specifically, are your anticipations of "boundary effects in modern orders"