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Function Talks at Ostrom Symposium
Well, Ralph Chapman has hit most of the highlights, so it will make my work
Alan Brush's talk was familiar to me, since it was very similar to the stuff
he had presented just four weeks earlier in Denver. An elegant study
showing (among other things) how any feather follicle can potentially
produce any sort of feather type (which we can demonstrate to a certain
degree because the same follicle will produce different feather types in the
same individual at different growth stages, different seasons, etc.). Also
continues to point out that the family of keratins from which feathers are
composed are unique to sauropods (the beta keratins), whereas alpha keratins
are widely distributed among vertebrates (and elsewhere).
Mary Schweitzer's talk updates her work from recent SVPs, looking at the
feathers of modern birds, the feathers of _Caudipteryx_, and the
integumentary fibers (she was very careful not to say feathers, although the
agreement is rapidly arising that that is what they are) of the
alvarezsaurid _Shuvuuia_ and of _Sinosauropteryx_. She looked at both
molecular and strucutral aspects of these elements. Unfortunately, no
photos as to how the feath... fibers were preserved around the skull of
Zhonghe Zhou discussed phalangeal and limb element proportions in
_Confuciusornis_, and argued very convincingly that it was more arboreal
than (say) _Archaeopteryx_. A cool bird, although one with almost no real
tail fan. However, statements that it could not have taken off from level
ground caused (rising expert on bird take off mechanics) Kay Earls to shake
her head: unfortunately, as with many subjects relating to aspects of
flight, people assume a whole bunch without the hinderance of experimental
data. Bird take off is one aspect; gliding is another. (In other words,
the mechanics of *THE* key aspects to the ground up or trees down debate are
still being experimentally examined).
Jim Hopson gave a good old-fashioned ecomorphometric study of theropod
(avian and otherwise) hands and feet. Caliper Science at its best! Glad to
see it; would've been glad to have done it myself! In hands OR feet
(non-ornithothoracines) or feet only (ornithothoracines), elongation of the
penultimate phalanx is associated with a good grasping ability; in the foot,
a long first phalanx and shorter distal phalanges is associated with faster
running. Archie hands plot very close to dromaeosaurs (and
_Confusciusornis_): it was a good grasper; Archie feet plot around the
coelophysids, reversing the trend towards greater "terrestriality" in
theropod toe dimensions. Conclusions: Archie was adept at both the trees
and the ground. (Incidentally, within many modern bird lineages, there was
a broad spread of arboreal and groundliving habits and proportions, showing
that there doesn't seem to be some sort of ecomorphological "lock" holding a
particular group in one mode of life).
Alan Gishlick (a Gauthier student) filled in for Nick Arnold, and talked
about his own new work on the limb mechanics of _Deinonychus_. Cool stuff
about semilunate carpals and rotation of joints and so forth. Incidentally,
like ornithomimosaurs (and some other coelurosaurs), _Deinonychus_ could not
hyperflex the digits of its manus. In fact, digit III can not be pulled all
the way into the plane of digit II. Probably not coincidentally, digit II
is the feather-bearing digit in _Caudipteryx_, Archie, etc., and presumably
the feather bearing digit in dromaeosaurids. This way _Deinonychus_ (and
Archie) kept digit III accessible on the inside surface of the hand
(meaning, incidentally, that the National Geographic sculpture of
_Caudipteryx_ is incorrect: digit III would be on the inner, not the outer,
surface of the wing). Don't know if I will bring up the "blinders theory":
Alan may be waiting to unleash that elsewhere...
Steven Perry talked about how diverse lungs are among amniotes, and the fact
there is no such thing as "THE Reptile Lung". Lots of work still to be done
to understand all the variables (and thus different approaches) to being a
Great Paul: Had seen a lot of this particular work in various stages before,
so not too much was new to me (although I really liked his _Caudipteryx_
restoration: the best done yet. Yes, the pubis looks to be vertical.)
Showed how earlier reconstructions of the narial passage of avetheropods (at
least) were flawed, and how the same in some birds with respiratory
turbinates fall within the range of the narial passage size in some
non-avian dinosaurs. Greg might post more later.
Ralph covered Ruben's talk in more detail already: one curious aspect was
that the pelves of crocodilians and theropods were "strikingly similar", yet
the pelves of theropods and _Archaeopteryx_ were only "superficially
similar". All I can say to that is: go to a museum, see the specimens in
3D, and make up your own mind. (Reminds me of aspects of Martin's talk, in
which *any* dissimilarity between basal birds and theropods was considered
significant, but any similarity was due to convergence. Well isn't that
Ralph also mentioned more about Rayner's talk: Rayner did indicate that just
as quadrupedal mammals have distinct gaits, flying birds have two distinct
"gaits" (toroidal and continuous vortices). (Okay, hummingbirds add their
own unique gait). The continuous vortex, associated with higher speed
movement, is actually the less morphologically demanding and presumably the
primitive; the more sophisticated toroidal vortex requires more complicated
morphologies and energetics, and even though assocaited with slower speeds,
is probably derived. In fact, Rayner suggested that Archie and other basal
birds were incapable of performing the toroidal vortex.
Ted Goslow's talk on the supracoracoideus muscle in starlings has recently
been published, and you can look up those details there. Some interesting
implications for the furcula as a site of muscle attachment as well as a
spring: this may indicate the primitive function of the furcula (in the
boomerang shape found in nonavian theropods and basal birds).
Steve Gatsey's talk paralleled much of what he presented (and I have
previously summarized) at the Denver SICB meeting. Gatsey suggested that
_Caudipteryx_ was similar to modern birds in having only six pairs of
retrices (tail feathers).
Phillip Burgess talked about load, energy, and power in the takeoff of
_Archaeopteryx_. Unfortunately, there was a bit of attacking of strawmen
here: he compared the "arboreal model" (which was summarized merely as a
parachuting model, although more and more we are recognizing that real
gliders begin with an active jump) with the "cursorial model" (which was
reduced to a "running full tilt and jumping after insects" model, which is
not what most of Ostrom's argument concerned) with his "kinetic model"
(which was really a cursorial model: flight began from fast running animals
which began to use their protowings originally for thrust, then for
ground-effect flight, and only later for lift). He had the distracting
habit of using the formal taxonomic name _Archaeopteryx_ as some sort of
catchall word for "protobird": we had a "running Archaeopteryx" phase, a
"ground effect Archaeopteryx" phase, etc.
The discussion: Schweitzer and Brush were asked a few molecular and
developmental questions; the Burgess, Gatsey, Gishlick, Goslow, Rayner,
Hopson, and Zhou crowd were asked a handful of questions (including a
taxonomic one!! Couldn't they have asked that the previous day?); and then...
Perry, Paul, and Ruben up for a batch of questions. Many of them had to do
with Ruben's contention that a) the hypopubic cup represents a fundamentally
different structure than a pubic boot and b) that the former could not be
derived from the latter. Others asked why would it be that a hypothetical
diaphragm breathing would be incapable of being the ancestor of birds.
Someone asked at one point (referring to Martin's assertion the previous
day) if any theropod had a laterally facing glenoid: Oliver Rauhut began to
cite specific specimen numbers from MOR and IVPP. At one point, Greg Paul
pointed out that we have basal dinosauromorphs with just a handful of
features shared with birds, and that as we get closer to dromaeosaurids we
begin to pick up exactly the same cranial, postcranial, pneumatic,
integumentary, etc. features we see in birds: "What more could be possibly
want?" (to which he got a series of applause and shouts from at least the
rowdy back of the room...).
Afterwards I overheard (at first, talked with later) various press types,
who said "well, that seems to have nailed the coffin shut on the
contraversy." I had to point out to them that except for the feathered
Chinese dinosaurs, most of this was known for a decade or three. They were
astonished. "Why is there still a contraversy, then?"
I couldn't hang around for too long, though, as I had to catch a late flight
back to D.C.
Looking forward to other reports and impressions from the Ostrom Symposium.
Oh, yeah, by the way: both I and Phil Currie showed up in tuxes to the Gala,
but Mary forgot her camera. Maybe at some other event...
Thomas R. Holtz, Jr.
Vertebrate Paleontologist Webpage: http://www.geol.umd.edu
Dept. of Geology Email:email@example.com
University of Maryland Phone:301-405-4084
College Park, MD 20742 Fax: 301-314-9661