Re: 11th specimen of Archaeopteryx

[Jason Brougham <jaseb@amnh.org>]

Yes, sir, Mr. Hartman and I have corresponded about it previously.

It may be true that a lack of humeral remiges corresponds with proportionally 
short humeri, or it may not: that is a hypothesis that can be tested (I don't 
think it should be assumed a priori). I am finding humeral remiges absent in 
sample galliforms (quails) and corvids (jays) in my preliminary pterylographic 
search. 

An experimental test would be simple: take birds with a humeral length to body 
mass ratio the same as the distribution in Archaeopteryx specimens of varying 
sizes, cut the humeral feathers, and see if  the modern birds can fly and/or 
what performance (if any) is lost. 

The reason I am skeptical is that the putative "gap" between the body wall and 
secondaries that is often mentioned is less of a gap if we consider that the 
humerus diverges from the body wall at something near 45 degrees, and that 
there is a broad propatagium as well, even in forms as basal as Microraptor. 
The gap then is reduced to a small notch between the knee and elbow. I wish I 
could attach a small diagram here to demonstrate.

I'll consult my copy of Nitsch's Pterylography and report back.


On Oct 27, 2011, at 6:45 PM, Habib, Michael wrote:

> Yes, that is the presentation I alluded to. Thanks for posting the abstract!  
> The modern birds with secondaries filling the inboard wing typically have 
> short humeri. Archaeopteryx also does not seem to have angled secondaries.  
> Scott Hartman would be the better individual to reply to that particular 
> query, though.
> 
> Cheers,
> 
> --Mike H.
> 
> 
> Sent from my iPhone
> 
> On Oct 27, 2011, at 5:52 PM, "Jason Brougham" <jaseb@amnh.org> wrote:
> 
>> Dr. Habib, is this the presentation at SVP Bristol that you mentioned?
>> 
>> Also, the literature says that some modern birds do not have humeral 
>> remiges, using proximally directed secondaries to fill that role. Is it 
>> possible it was the same for Archaeopteryx?
>> 
>> Poster Session II, (Thursday)
>> FLIGHT MORPHOLOGY AND LAUNCH DYNAMICS OF BASAL BIRDS, AND
>> THE POTENTIAL FOR COMPETITION WITH PTEROSAURS
>> WEISHAMPEL, David, Johns Hopkins University, Baltimore, MD, USA; HABIB, 
>> Michael,
>> Johns Hopkins University, Baltimore, MD, USA
>> Birds inherited a bipedal gait and feathered airfoils from their theropod 
>> ancestry. These
>> features produce specific tradeoffs with regards to launch, maximum size, 
>> lift coefficient,
>> and limb disparity. There are subtle effects related to the use of feathered 
>> wings, such as
>> the ability to utilize separated wingtip slots and extensive span reduction, 
>> which have
>> also influenced avian flight evolution. Combining information from 
>> structural mechanics,
>> aerodynamics, and phylogeny, we conclude that the basal state for avian 
>> takeoff was a
>> leaping launch, not a running launch. We find that several morphological 
>> features of early
>> birds, inherited from theropod ancestry, predisposed them to radiation in 
>> inland habitats. We
>> find that Archaeopteryx could sustain substantial loads on both its 
>> forelimbs and hindlimbs,
>> but structural ratios between the forelimb and hindlimb of Archaeopteryx are 
>> indicative
>> of limited volancy. Limb strength in Confuciusornis was modest, suggesting 
>> an emphasis
>> on cruising flight and limited launch power. We find little evidence to 
>> support extensive
>> competition between birds and pterosaurs in the Mesozoic. Prior literature 
>> has suggested
>> that pterosaurs competed with early birds for resources and may have helped 
>> shape the early
>> evolution of birds. There is some evidence of partitioning between 
>> pterosaurs and birds in
>> ecological space. Evidence from the Jehol fauna suggests that pterosaurs 
>> dominated near
>> coastlines during the Early Cretaceous, while birds were more important 
>> inland. However,
>> flight is a complex character. Flight mechanics vary considerably across 
>> volant animals.
>> Some flyers experience only limited competition for resources with other 
>> flying species,
>> and might compete most intensely with non-flying taxa. As a baseline for 
>> understanding the
>> interactions between Cretaceous birds and pterosaurs, the flight dynamics of 
>> the two groups
>> need to be compared in a quantifiable framework. Birds and pterosaurs 
>> inherited different
>> morphologies, and this impacted their flight regimes. Comparing the two 
>> systems provides
>> a basis for hypotheses related to competition in the Cretaceous, and the 
>> influences on early
>> avian evolution.
>> 
>> On Oct 27, 2011, at 4:21 PM, Habib, Michael wrote:
>> 
>>> Also, the possible (likely) lack of a complete inner wing and the 
>>> relatively weak forelimbs (see Weishampel and Habib presentation at SVP 
>>> Bristol for the latter; full paper still pending as we are adding to it).
>>> 
>>> Cheers,
>>> 
>>> --Mike H.
>>> 
>>> Sent from my iPhone
>>> 
>>> On Oct 27, 2011, at 3:55 PM, "David Černý" <david.cerny1@gmail.com> wrote:
>>> 
>>>> David Marjanović <david.marjanovic@gmx.at> wrote:
>>>> 
>>>>> What are these, other than the apparent inability to lift the wing above
>>>>> horizontal?
>>>> 
>>>> The (admittedly controversial) feather study of Nudds & Dyke (2010), 
>>>> perhaps?
>>>> 
>>>> Nudds RL, Dyke GJ 2010 Narrow primary feather rachises in
>>>> _Confuciusornis_ and _Archaeopteryx_ suggest poor flight ability.
>>>> Science 328(5988): 887-9
>>>> 
>>>> -- 
>>>> David Černý
>> 
>> Jason Brougham
>> Senior Principal Preparator
>> American Museum of Natural History
>> jaseb@amnh.org
>> (212) 496 3544
>> 
>> 

Jason Brougham
Senior Principal Preparator
American Museum of Natural History
jaseb@amnh.org
(212) 496 3544