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Re: Science feather strength debate



Yeah, also, what exactly is the aerodynamic function of tertials? A wing
is not a sail or a  parachute. The feathers closest to the armpit move the
slowest and the least far during a flap, so do they even generate any
lift?


> Agreeing with your opinion, as far as I am aware, as the bird humerus
> is surrounded by muscle in a greater measure than the ulna, it is to
> be expected that the plumage is not so firmly attached to the skeleton
> at this point, and it may thus be more easily disarticulated with
> decay. Correct me if I am wrong, but I never read or saw first-hand
> humeri with feather knobs, while they can be found in the
> carpometacarpus in addition to the ulna. If true, the lack of these
> feather attachment structures may suggest feathers were not attached
> to the humerus.
>
> 2010/11/14 Tim Williams <tijawi@gmail.com>:
>> David Marjanovic <david.marjanovic@gmx.at> wrote:
>>
>>> Regarding life in trees, how good a glider can *Archaeopteryx* have
>>> been when it had that gap between wing and body,
>>
>>
>> I'm not wholly convinced that _Archaeopteryx_ lacked humeral feathers
>> (= tertiaries or tertials).  Modern birds have three or four of these,
>> proximal to the innermost secondary feathers.  However, no known
>> _Archaeopteryx_ specimen exhibits feathers associated with the
>> humerus.  For example, the flight feathers in the Berlin specimen are
>> preserved on the distal forelimb right up to the elbow, where the
>> feathers stop dead: no tertiaries.  This has been cited in support of
>> the flight surface of _Archaeopteryx_ being discontinuous, with a gap
>> between the wing and the body wall where the tertiaries would
>> otherwise be (e.g., Garner et al., 1999 - the "Pouncing Proavis"
>> model).
>>
>>
>> However, two things make me skeptical about this interpretation.
>> Firstly, some crown-group birds from the Messel are also found without
>> tertiaries preserved, although the outer flight feathers are clearly
>> preserved.  In these cases, the absence of tertiaries is certainly
>> preservational.  So the same may be true for _Archaeopteryx_.
>> Tertiaries were likely not as firmly attached to the wing as primaries
>> and secondaries, and may have come loose.
>>
>>
>> Secondly, Mayr et al. (2007) mention what could be evidence of
>> tertiaries in the "Tenth Archaeopteryx".  They describe "marked, fuzzy
>> furrows at the ?elbow joint? which may stem from the tertiaries".  As
>> positive evidence goes, this is admittedly weak.  But overall, I
>> wouldn't write off the possibility that _Archaeopteryx_ had
>> tertiaries, and therefore the wing was complete, right up to the body
>> wall.
>>
>>
>>
>> Cheers
>>
>> Tim
>>
>


Jason Brougham
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Department of Exhibition
American Museum of Natural History
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