Re: Vegavis gen. nov. - new anseriform in today's Nature

[David Marjanovic <david.marjanovic@gmx.at>]

----- Original Message -----
From: "Graydon" <oak@uniserve.com>
Sent: Friday, January 21, 2005 6:22 PM

> > If substantiated, it also means that the chicken/duck split was
> > pre-K/T--mass survival.
>
> Sure.

It shows that the chicken/duck split was earlier in the K. But how is this 
mass survival?

--+--Palaeognathae
 `--+--+--Anseriformes (*Vegavis*)
    |  `--Galliformes
    `--Neoaves

*Vegavis* tells us _nothing_ on how much, if at all, Galliformes and Neoaves 
had diversified before the K-Pg boundary.

> People are generally proposing 'dumb luck'; a very few neornithine
> species made it over the boundary, along with maybe *one* Gondwanan
> ratite species.  (Or maybe more, but not a dozen.)

Need not even have been a ratite. Judging from the current knowledge of the 
fossil record one basal paleognath species is enough. Of course, this can 
easily mean _one population_ of that species.

> It would then have to find food and a mate and food for offspring, and
> the dire conditions in which to do so would last for a long time;
> hundreds of generations.

_This_ is where criteria like "ability to live off seeds", "ability to live 
of insects", "ability to eat any organic material that isn't outright 
poisonous", "ability to fly", "ability to get by without food for many 
months" and the like kick in.

> > And why would one exempt na dinosaurs (especially juveniles) from
> > opportunistic feeding.
>
> Because the dire ecological consequences of the event lasted for, at a
> minimum, a thousand years.  Juvenile non-avian dinosaurs would have to
> reach sexual maturity in a landscape devoid of sufficient food to do so.
>
> Note that *nothing* terrestrial with an adult body mass over 10 kg made
> it.  That says a great deal about food availability.

Very well said.

> > And it is not just ducks, but chickens now (whatever they were in the
> > Cretaceous).
>
> More or less what they are now -- jungle fowl.

(At least this is thought to be the plesiomorphy for Galliformes.)