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Re: Fwd: the largest Pterosaur

> Hi Mike,
> To be honest, the remains of these giants are so scrappy that I feel
> we're clutching at straws trying to guess their size and mass.

I agree with that; especially for Hatz.  For Q. northropi there is the 
advantage of having Q. sp. for some comparisons.

> To me, the humerus of Hatzegopteryx and Quetzalcoatlus look a bit 
> different:

> Hatzegopteryx has a relatively slender deltopectoral crest compared 
> to Quetzalcoatlus, but, conversely, appears to have a thicker diaphysis
> (like yourself, these observations are based on photographs).

I agree that they look different (in precisely the manner you mention).  I 
guess what I was trying to say was that I'm not particularly confident of my 
assessment.  The fact that you and Jim seem to agree on that observation adds 
some substantial weight to the evaluation.  I will say that it appears to me 
that the dp crest in Hatz is missing a pretty substantial piece near its base.  
That makes me think that it may be about as broad as Q. northropi's dp crest at 
the base, but perhaps more gracile at the tip.  Of course, this would make for 
a slightly oddly shaped dp crest by azhdarchid standards.  Just a thought worth 
tossing out there.

> Still, if Hatzegopteryx did have a greater wingspan, I reckon it
> would've weighed more. Increased body size generally corresponds with
> increased mass (though not in a linear relationship, of course) and,
> with all the additional flight musculature needed to flap those
> expansive wings, I think an azhdarchid with a 14 m wingspan would weigh
> a lot more than an 11 m specimen.

True, though I have my doubts about a 14 m wingspan.  The power needs increase 
disproportionately, as well, because the distal wing contributes the most to 
wing inertia.  I wasn't thinking of a span difference quite that large when I 
suggested that the masses could be close.  My rather vague point was just that 
the animals might not be built in exactly the same manner, given the possibly 
more gracile dp crest in Hatz.  Thus, Hatz _could_ be proportionately more 
gracile, but that is very speculative.  And certainly, if there were really a 3 
meter span difference, I would expect Hatz to be much larger (like Jim said, 
roughly 95% larger would be a reasonable estimate).

> I think we sometimes forget with all
> these measurements that something like a 3 m difference (to use the
> example here) is actually quite a big distinction: the walls in the room
> I'm sitting in now are about 3 m tall, which is a significant dimension.
> It's all relative, of course: 3 m might mean a lot to comparisons
> between 10 -14 m pterosaurs, but comparatively little to gigantic, 30 m
> + sauropods. All the same, even accounting for increased pneumatisation
> and all that, I think it's hard to avoid a extra mass if your azhdarchid
> has a wingspan one-storey broader than another (if that makes any
> sense).

It makes perfect sense.  Good analogy, too.  I suppose I was being a bit 


--Mike H.