Re: Proto-penguins lived with dinosaurs

[Michael Habib <mhabib5@jhmi.edu>]

> I managed to overlook this -- but look at what it says later in the 
> article:
>
> > >
> An Otago University geologist, Associate Professor Ewan
> Fordyce, said modern theory was that most modern bird
> groups evolved after the dinosaurs died out.
>
> "By using the dates from the fossil Waimanu penguins as a
> calibration point...

Thanks David; that was the section I was referring to in my earlier 
post.  I almost missed it as well, and it certainly is confusing.  The 
reason that I knew for certain that it was a standard fossil 
calibration, incidentally, was that I had spoken to Ewan Fordyce in 
person about the study, previously.  The article, certainly, is not at 
all clearly written. Sigh.

On Sunday, April 9, 2006, at 04:13 AM, Jaime A. Headden wrote:

>  *Waimanu* itself does not appear to be a "penguin" form 
> sphenisciform. It
> possesses longer, albeit still flightless, forelimbs, jointed elbows, 
> implying
> a possibly different wingstroke, less robust bones, and a more slender
> mandible, resembling something more akin to a loon to my eyes.

Well, the differences are fuzzy, certainly, and I specifically singled 
out postcranial similarities because, indeed, the skull is not very 
sphenisciform.  The forelimbs, however, are flattened dorso-ventrally, 
and have thickened cortices.  The hindlimbs are very penguin-like.  The 
coracoid is somewhat ambiguous, but it is pretty robust.

The wing joints are indeed held more acutely than in modern penguins, 
but they may have still been immobile.  There isn't enough material to 
determine yet whether the elbows were locked in place as in modern 
penguins.  Owing, in part, to the fact that we don't know if there were 
sesamoids developed at the elbow yet or not.  I suspect that there 
were, though, because I cannot see much of an olecranon on the ulna.  
It might change the wingstroke, but I actually doubt it would have a 
huge effect.  For one thing, amphibious fliers largely immobilize the 
elbow and wrist while flying underwater anyway (especially on the 
downstroke), despite having folding wings.  You could be right though; 
perhaps the upstroke was not fully developed as a thrust-producing 
stroke yet.

Cheers,

--Mike Habib