Re: Dinosaurs and birds

[Michael Mortimer <mickey_mortimer111@msn.com>]

Scott Hartman wrote-

> It had sure better be.  Outside of the assymetrical feathers (which is a 
> drag-reducing adaptation, not a lift-generating one, although the two are 
> related) there isn't any terribly good reason to assume Archaeopteryx was 
> volant.  It _may_ have been, but it would have to get around the glenoid 
> not being oriented for completel upstrokes, the lack of an ossified sternum 
> for hypertrophied musculature attachment, the lack of a pulley-like 
> supracoracoideus needed to prevent dislocation of the humerus during 
> downstrokes, and some problems with the wings (you'll hear more around SVP 
> time).

What does Sapeornis bring to this issue?  It didn't have an ossified sternum 
either, and its short coracoid (shorter than most other maniraptorans in 
fact) and reduced acromion process suggest its supracoracoideus was even 
less flight-adpated than Archaeopteryx, correct?  Yet it has huge arms with 
a well developed deltopectoral crest and reduced manual digit III.  Do you 
believe Sapeornis was flightless too?

T. Michael Keesey wrote-

> Maybe he never threw his full support behind it, but:
>
> "More interesting is to consider the possibility that sauropods are basal 
> to
> all other dinosaurs, that prosauropods and ornithischians are sister 
> groups,
> and that theropods are a sister group to the prosauropod+ornithischian 
> group.
> This is what the feet say, anyway."
> (from http://dml.cmnh.org/2002Aug/msg00030.html)

Just to clarify, "what the feet say" was in reference to the amount of 
phalanges on pedal digit V, which Olshevsky finds to be incapable of 
increasing through evolution.  Thus sauropods must be basal to even early 
dinosauromorphs like Silesaurus and Lagerpeton, because they sometimes have 
two phalanges on digit V.  Crazy single character analyses...

Mickey Mortimer