[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: 11th specimen of Archaeopteryx

Are there any examples of non-soaring birds that incorporate the
humeral remiges (=tertials, by the way) into the active plane of the
wing? In many examples I've found these aren't really flight feathers
but slightly more pennaceous and more like glorified shoulder/scapular
feathers, basically acting as filler when the wing is slightly
extended or serving as a protective cover for the active remiges when
the wing is folded. Non-soaring birds don't seem to fully extend the
humerus when in flight, making true remiges on the humerus

Note the fourth image in the right column here: the tertials are the
three innermost feathers of the wing and nearly completely overlap
each other even when the wing is extended:

IIRC, the description of the Thermopolis _Archaeopteryx_ noted faint
traces of long "plumulaceous" feathers on the humerus that may be this
type of tertial.


> On Thu, Oct 27, 2011 at 11:16 PM, Habib, Michael <MHabib@chatham.edu> wrote:
>> 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.
>> Cheers,
>> --Mike H.
>> 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.
>>>> 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)
>>>>> 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
>> Michael Habib
>> Assistant Professor of Biology
>> Chatham University
>> Woodland Road, Pittsburgh PA  15232
>> Buhl Hall, Room 226A
>> mhabib@chatham.edu
>> (443) 280-0181