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Re: 11th specimen of Archaeopteryx
Excellent; sounds like you're off to a roaring start and I (and others here,
I'm sure) will be very eager to see what you find! One thought is that it may
be informative to standardize humeral length by another long bone element, in
parallel to the body mass standardization run. I think the results might be
different in important ways.
On Oct 27, 2011, at 7:16 PM, Jason Brougham wrote:
> 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.
>> --Mike H.
>> Sent from my iPhone
>> On Oct 27, 2011, at 5:52 PM, "Jason Brougham" <email@example.com> 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,
>>> 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).
>>>> --Mike H.
>>>> Sent from my iPhone
>>>> On Oct 27, 2011, at 3:55 PM, "David Černý" <firstname.lastname@example.org> wrote:
>>>>> David Marjanović <email@example.com> wrote:
>>>>>> What are these, other than the apparent inability to lift the wing above
>>>>> The (admittedly controversial) feather study of Nudds & Dyke (2010),
>>>>> 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
>>> (212) 496 3544
> Jason Brougham
> Senior Principal Preparator
> American Museum of Natural History
> (212) 496 3544
Assistant Professor of Biology
Woodland Road, Pittsburgh PA 15232
Buhl Hall, Room 226A