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

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

> > It's true that they refute Feduccia's extreme version. Fossil evidence 
> > for a
> > diversification of Neoaves in the K is however still lacking, as the 
> > article
> > itself stresses.
>
> "Extreme version"????

In 1996 at least, Feduccia thought that the crown-groups of Palaeognathae 
and Neognathae were entirely Cenozoic. (Can't live with a Cretaceous duck.) 
A less extreme version is the idea that only the crown-group of Neoaves, or 
only those of, say, Metaves and Coronaves, are Cenozoic-only. (Can live with 
K ducks, but not with K parrots.) The opposite is what the molecular 
divergence date estimates of the last 10 years say: that most if not all 
divergences between the extant bird "orders" happened in the Cretaceous. 
(Requires both K ducks and K parrots.)

> Birds should have been affected as badly as non-avian dinosaurs.

Why do you think so? Most birds have advantages on their side that most 
other dinosaurs lacked:
- Small size. Means, large populations, low food requirements, easier to 
find shelter...
- Flight. Means the ability to cheaply cover vast distances in search of 
food, mates, nesting sites and whatnot. This in turn means that much fewer 
individuals per continent need to survive to continue the species.
- Ability to live off seeds (Galliformes, Palaeognathae).
- Ability to live off insects (Galliformes, Palaeognathae, who knows what 
else).
- Being part of ecosystems that aren't based on living plant parts 
(especially in freshwater; Anseriformes, whatever).

> The more species we find that are ancestral to extant species, the
> less support there is for an instantaneous, all-encompassing catastrophe.

Evidence for Cretaceous members of Neoaves -- a huge clade! -- is still 
quite poor. Besides... the more species we find that are _not_ ancestral to 
extant species, the _more_ support there is for an instantaneous, 
all-encompassing catastrophe... and this, too, is going on now, partly by 
new finds (the toothed bird of Maastricht, *Limenavis*...), partly by 
revisions of known specimens (*Iaceornis*, probably *Polarornis* and 
*Neogaeornis*...).