Re: Waimanu & avian evolution (comments)

[Michael Habib <mhabib5@jhmi.edu>]

> They are synthesizing a model to explain the pattern of diversity, 
> size, and
> extinction of pterosaurs.  From Unwin (2003) they report a long 
> pterosaur
> decline in diversity and deem the bolide practically irrelevant 
> because of
> it...i.e., other forces were at work.

A long decline is important, but given the diversity of late Cretaceous 
large-bodied pterosaurs (a diversity that was much higher than 
previously thought, it now seems), I think the bolide would have to 
remain pretty relevant.

> I think it's fair to compare diversity _within_ the pterosaur taxon, 
and,
> noting a decline there, correlate it with a within-taxon rise in 
> neornithine
> diversity.

Okay, I'll buy that; though for the sake of debate I'd like to toss out 
the idea that loss of small-bodied forms and gain of large-bodied forms 
isn't really an overall decline in diversity.  But then, I don't think 
you meant an overall decrease in diversity anyway.  I follow your point.

> Re: Falconiforms...I think what may be
> coming more clear is the incredible airworthiness of the aft 
> adaptations for
> aerial agility!  In my view, nasty claws and beaks are relatively
> off-the-shelf features compared to say, a tail fan.  Is this 
> reasonable?

It depends on how you look at it.  Tail fans seem to be present in 
neornithines prior to Falconiformes (likely back to ornithothoraces), 
but the raptorial armament was probably derived within the lineage.  
Thus, when you get to the first falconiforms, tail fans should be a 
given, but the weapons may or may not be present.  On the other hand, 
nasty claws certainly do pop up more often in the tree overall than the 
origin of tail fans.  Also, the importance of tail fans for agility and 
maneuverability is complicated; some of the most agile birds have 
almost no tail fan at all.  Raptors do use their tails extensively, 
however (though use varies quite a bit between taxa).

> > Of course, I would also love to hear everyone's thoughts regarding the
> > dated tree itself, which is ultimately the most important part of the
> > paper.
>
> Interesting that no one here took up that challenge--or, did I miss it?

You didn't miss it; the challenge didn't draw any contenders.


Cheers,

--Mike Habib