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Re: Ah ha! That's where therizinosaurs came from



What about ratites? How do we know they had flying ancestors?

My point is that ratites do not retain any single anatomical feature that
is found only in flying birds. I realized last week that, if we look at
the anatomy only, ratites could retain the anatomy of an avialan lineage
that diverged right before flight was attained. I was surprised when I
realized that.



> One reason I realized that dromaeosaurs were likely to be neoflightless
> was
> because when I examined the Eichstatt specimen in 81 was it was plain as
> day that the palate was theropodian not avian in grade, so that did in the
> argumment that it was a "bird" more derived than dromaeosaurs since Archy
> does
> not have a whole lot else indicating it is closer to modern avians than
> the
> sickle claws. I also learned on the same trip that dromaeosaurs had
> ossified
> uncinates and sternal ribs in addition to the big sternal plates and
> pterosaur like tail also absent in Archy, plus the folding arms. I figured
> I would
> just wait oh about 30 years for the winged dromaeosaur fossils to show up
> supporting the hypothesis. So it's a mixture of flight adaptations and
> phylogeny.
>
> GSPaul
>
>
> In a message dated 8/14/11 9:21:10 PM, jaseb@amnh.org writes:
>
> << It was me that wrote that there is no unambiguous anatomical evidence
> that
>
> ratites had flying ancestors. I wrote that the way we can infer that they
>
> are secondarily flightless is in phylogenetic context - since so many
>
> birds that were more primitive flew. Thus the only way to demonstrate
>
> neoflightlessness in their case is phylogenetic, not anatomical, analysis.
>
>
> Would you agree? >>
>
> </HTML>
>


Jason Brougham
Senior Principal Preparator
Department of Exhibition
American Museum of Natural History
81st Street at Central Park West
212 496 3544
jaseb@amnh.org