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Re: Pterosaur size


------- Why not? Current atmoshperic conditions wouldn't stress either them
or any of their ancestral line.......

You keep telling me that, but I'm skeptical. Wingstroke amplitude and landing speeds are 2 reasons why.

Why is wingstroke amplitude a problem? The quetz shoulder that I have lying here on my desk doesn't have a wingstroke amplitude problem. Available amplitude is far greater than articulated stripwise flapping calculations indicate would be needed to maintain level flight in no-lift conditions.

And why is landing speed a problem? It sounds like you may be expecting the animal to have to land as speeds approaching the steady-state stall speed. Needless to say, they don't have to do that. Again, its a matter of technique.

The trend I see in the fossil record is another. Your statements about launch modes are interesting, your knowledge base is evidently comprehensive, and for all I know you are right. But I am still skeptical.

Which is certainly your prerogrative, and a conservative stance. I applaud that.

Like I said, it is an opinion.

I got lost. What's an opinion? If you're referring to potential launch and landing techniques, they meet the requirements for a hypothesis and can be either proven as possible or disproven as possible.

Too bad we aint got a few million years, because I have been known to place a bet.

If making a bet would give me a few million extra personal years, you'd be on (and I wouldn't care who won :-)

The physical properties of the atmosphere constrain many processes, including flight.

Re flight, I had sort of come to that conclusion myself over the years. What I find enthralling are the many ways in which animals address that issue and use it to their benefit. None of the animals we've been discussing are particularly close to atmospherically constrained flight issues. Several of them are close to launch constraints due to avenues taken by their predecesors -- others aren't. I note in passing, that geese and swans have been reported by pilots at altitudes of 17000 feet, where the density ratio is 0.59 (a 41% reduction from sea level). You are proposing that density variations of 15% are critical. That occurs at an elevation of about 5500 feet, where the density ratio is 0.85 (a 15% reduction from sea level). Does that mean that a modern bird suited for flight near sea level would be ground bound at 5500' MSL ? Does that hold in practice? Swans (a group that includes the heaviest individual bird known to flap by means of continuous flapping) spend a lot of time near sea level, but certainly aren't limited to elevations less than 5500 MSL.

It is my opinion that a slow directional change in the physical properties of the atmosphere provides the best fit for the fossil record as a whole. In my opinion, the direction is such that "tomorrow" (say, 10 mys) will be even less pterosaur-friendly than today..

If so, then it would be even less friendly to birds and bats, both of whom face more flight strictures than pterosaurs. 

In fact, I think the current size limit for flapping flight is below
Argentavis, and somewhat above the largest birds living...

---------I tend to agree with this particular statement, but what do avian limits
have to do with pterosaurian (or bat) limits?

Actually, you don't agree, except as it applies strictly to birds. 

You yourself restricted the statement to birds.  Re-read it     :-)

I meant to include bats and pteros. See below.

even considering that some systems are superior to others, which to my
mind just increases the variance, but doesn't affect the slope of the
moving average. Just an opinion.

This implies that you assume all animals fly by utilization of exactly the same techniques, materials, and power sources. Is that indeed the case?

But it is there. (insert - moving average) 

Is that speculation, or a demonstrated fact?


You may feel that it is irrelevant, and you may be right to dismiss. But it is there.
Largest volants in time sequence: Q. n, various pseudodontorns, A. mag, Pseudodontornis, T. incredibilis, T. merriami, California Condor.

You are mixing and matching two different structural systems, and three types of flight mechanics. Apples and oranges, perhaps ?

In wing span sequence: Q. n, A. mag, various pseudodontorns, Pseudodontornis, T. incredibilis, T. merriami, California Condor. 

Same statement applies.  Or, oranges and pears if you prefer   :-)
As an aside, when did A mag get to be older than the psuedodontorns?

If you accept that the trough after K/Pg is caused by a catastrophic event, and smooth accordingly, you get a distinctly non-fluky looking curve that is ~100 mys long, without need for any statistical manipulation whatsoever. The negative correlation of wingspan to time (past to present) is better than -.95.

Women's skirt lengths in the 20th century show a strong correlation to the manufacture of horse whips. Does that mean that changes in one caused the other?

Corrections appreciated. I find it compelling.

I'm sorry, I don't. I do find variations in launch technique interesting though.

But that is just my opinion. Correlation is strong even if you punch in some of the comeback kids post-K/Pg... 

Wanna buy a horsewhip?

-----------------Individual birds do it in a few days, in response to changes in wing area
because of the moult. Birds that lose, say 30% of their wing area during
the moult also tend to lose about 30% of their body mass (which does reduce
their efficiency, but also allows them to continue to fly without much
alteration of performance).

Yes. Although that is not morphic optimization in the evolutionary sense.

True. I didn't imply that it was.