Re: 11th specimen of Archaeopteryx

[Jason Brougham <jaseb@amnh.org>]

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