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Re: Screaming dromaeosaur biplane killers of the air



Geeez, people are not even getting basic terminology right in this 
discussion. 

Flight, Websters - passing through the air by the use of wings - I suppose 
this covers helicopter blades and wingless flying bodies. A sailplane and a 
nonflapping albatross fly just as much as an F-16 on afterburner or a pigeon 
taking off. Flying squirrels fly as much as a hang glider. There are 
different kinds of flight, some internally powered such as Spitfires and 
racing pigeons, others externally powered (gravity and sometimes rising air) 
such as condors, sailplanes and flying snakes. Whether flapping flight is 
"truer" than wave soaring is open to question, in any case it is necessary to 
be specific when addressing the issues of different kinds of flight.

Headden wrote:

  I did not measure *C. volans* [that's C. pauli], given that the slab is 
underlit  in the
Czerckas publication [the phoots are excellent]and it is not apparently 
possible, as least with the
scans I have, to see integument in much light. The photo of the LPM type
in Norell et al. does not show how these are perfectly and fully
preserved, and I do not trust Czerckas' allusion of lengths given tyhe
conflation of the leg feathers to arm feathers. If anyone has better
pictures of these regions, I would love to see them. However, my
measurements for *M. gui* and *Archaeopteryx* stand, as they were made
from the scales figured in their respective papers and, of all things,
Greg Paul's _Dinosaurs of the Air_. The longest preserved feather of *M.
gui* is shorter than the arml measured from glenoid to the tip of the
second finger's claw.

Reply: I never claimed the primaries were longer than the arms. In most 
flying birds the primaries are shorter than the arms, confusciusornids being 
an interesting exception. What is true is that the primaries are longer 
relative to the hands than they are in Archaeopteryx, and are closer to the 
modern flyiing bird condition in this regard. 

<The most proximal preserved ulna feathers are also long, about as long as
the ulna, maybe  longer - it being difficult to be exact from the photos,
and there are badly placed sediment breaks in both specimens.>

  In *M. gui*, the secondaries wrap around the ulna on the right side, and
it is not likely there was a vacent space inboard of the elbow.

R: Not sure what H means here. 

<When the wing is posed in a normal flight position it has a moderate,
fairly typical forest bird chord/span ratio,>

  Considering I measured the chord and span from the given figure, and now
again from the photo, I get a anspect ratio of around 5.25, lower than in
forest birds.

R: How H can calculate such a ratio via photos and when the specimens are 
damaged in these areas is a mystery. 

<The wings were therefore fully capable of generating as much lift as
modern bird wings, and had high thrust potential as well.>

  This statement must be based on a mechanical analysis, not how wing
shape and aspect are similar to flying birds today or the assumption that
*Archaeopteryx* was a fully capable flapping flyer, a similarity I note
throughout _Dinosaurs of the Air_. Very few biomechanical analyses have
been made on fossil birds in this regard, and its about time we start.
Well, get the ones that aren't published finished and published, anyway.

R: H is setting up more strawman arguments here. As per my statement, the 
fact that the arm wings were about as large as those of birds, and consisted 
of fully developed aerodynamic feathers, shows there is no doubt they could 
generate all the lift needed for powered flight, ergo they had the potential 
(read the word H), to power fly via flapping.
I do not "assume" Archaeopteryx could power fly. In DA I go into great detail 
showing why Archaeopteryx is much better adapted for powered flight than any 
known glider. Gliders tend to have smaller airfoils, and lack flapping 
skeletal adaptations and muscle supports which Arch has. Since the winged 
dromaeosaurs are much better adapted for powered flight than Arch as I detail 
in DA, they were better powered fliers than the latter.  

<The large size of the wings is readily apparent in the articulated type
M. gui. To consider these enormous, fully refined arm wings merely
maneuvering control surfaces, or compare them the dinky little,
symmetrical, frayed edged feather arrays on the wee arms of Caudipteryx,
is absurd.>

  I really doubt they were frayed. The entire skeleton of the specimens of
those that have the best preserved wings are nearly wholly disarticulated,
often lacking all of the dorsals, the hips are disarticulated, and the
legs hardly in their natural positions (this is especially true of the
holotype), which argues that the "fraying" is evidence of dessication and
trauma to the animal postmortem. The vanes of the wings of better
articulated specimens, such as BPM 0001, do not show this "fraying" and
the rachis, unlike the type NGMC specimen has curvaceous rachi, hardly a
natural condition. As for the "enormous" wings of *M. gui*, what is the
comparison based on?

R: H, as I explained in my posts, the wing area/mass ratio of the winged dr
omaeosaurs plots in the middle of the avian range. That is enormous by 
definition, since flying birds have enormous arm feather arrays. 
BPM 0001 has unfrayed arm feathers? It hardly has preserved feathers at all 
according to the original descriptions in 2000. The authors did not even 
bother to describe the feathers of 0001 or 12430. I examined the small hand 
feathers of NGMC and they are frayed in a manner similar to the reduced wings 
of the nearly flightless kakapo.  

<As I detail in DA, the Johel dromaeosaurs have a large set of arm,
pectoral girdle, and trunk adaptations for advanced flight not present in 
Archaeoptryx, which itself was probably a competent powered flier, not
just a glider. In no regard are the flight adaptations of the
dromaeosaurs'  forelimbs inferior (read the descriptions of the various
Johel coracoids and study the illustrations carefully).>

  These birds lacked a sternal keel [R: also true of bats and confuciusornid 
grade birds], humeral elevator [R: you mean fully developed avain system, 
absent in bats and and confuciusornid grade birds]], reduced lateral
coracoid edge [R:so?], lower coracoid tubercle, unfused uncinates to ribs [R: 
entirely absent in flying screamers, did you bother to carefully read DA and 
look at the pretty pictures I labored over?], fused
carpus [R: absent in pterosaurs and bats], broadened proximal digits of the 
fingers [R: wrong, wrong, wrong, read the literature and look at the 
published illustrations including DA before stating such blatent untruths], 
vennate alulae [R: absent in pterosaurs and bats, partly present in the 
flying dromaeosaurs]
(previously referred, I will fill this in in my reply to Jim).... This
data seems to have been ignored [R: you ignore the actual data and the actual 
presence/absence of flight adaptations in powered fliers]. This makes them 
"not so good flyers", not
power flyers, which is still assumptive of *Archaeopteryx* as well, which
has a smaller sternal surface as far as is known than birds or basal
dromaeosaurs, or even oviraptorosaurs. The idea that *Archaeopteryx* was a
good flyer, and therefore animals with similar anatomy to Archaeopteryx,
upon the assumption that Archaeopteryx was basal to these forms, were
better at "flying" ... there are too many assumptions here, and not enough
data [R: there is far more data than you are aware of].

<The spherical femoral head of the type Sinornithosaurus is pictured in
the Nature description, my hi-res photos verify it.>

  I would really like to see this, if you would care to share it, as my
photos show an unelevated humeral caput that would have prevented lateral
extension of the femur. Not even birds can spread their femora dorsally in
the lateral direction.

R: No birds have wings on their legs. Citing bird and other dinosaur femoral 
head morphology is entirely irrelevant, we are examining Jehol dromaeosaurs 
here. This strawman argument is similar to saying that humans cannot have 
brains over 1 kg in mass because no other similar sized primates have them. 
The femoral head of the type Sinornithosaurus is dramatically different in 
form from those of other dromaeosaurs, dinosaurs and birds - which in 
retrospect I missed because I had no idea of its importance - with no 
cylinderical form, the articular surface seeming to extend laterally forming 
a proximally oriented spherical head, and no prominent lateral trochanters 
that will interfer with a sprawling posture (this is correctly figured in Fig 
2 Nature 401:262, and can be seen in the accompanying photo). So my below 
statement still stands.....

<Combined with the splayed out hindlegs of the completely articulated
spread eagled sinornithosaur later described in Nature and the presence of
well developed leg wings, the burden is upon those who wish to challange
the ability of Johel dormaeosaur legs to sprawl. Citing the condition on
later dromaeosaurs and troodonts is not pertinent since these are more
derived, smaller armed, flightless forms that had no need for sprawling,
spherical femoral heads. It is called evolution, in this case reversal
(probably genetically simple) to the ancestoral condition due to a return
to the ancestoral, nonvolant lifestyle.>

Note: Oops. I forgot that the Microraptor type is also preserved with the 
legs splayed out, and without evidence for disarticulation although damage 
makes the situation nondefinitive. More evidence for sprawling! 

  Contrary to these data, it seems the data I presented was overlooked a
tad. NGMC 91 lacks known humeral proximal ends {what does this have to do 
with LEG function?], which however articulated
the rest of the body, goes along with the missing pelvic material. Despite
all this, the large, terrestrial *Bagaraatan* [has nothing to do with the 
discussion of the Jehol dromaeosaurs] has a spherical and elevated
femoral caput that surpases the height of the trochanteric crest, unlike
either *Sinornithosaurus* or *Microraptor*. When the trochanteric crest
contacts the ilium, dorsal elevation is no longer possible, and this is
the first reason why the above quoted conclusion is erroneous. Another is
preservational: Even *Confuciusornis* is preserved on its side, a datum
used to determine avian affinity by some, and the reverse of the
"spread-eagle" pattern (also seen in *Confuciusornis*) with a high
trochanteric crest, a femoral caput more medial than dorsal as in the
other dinosaurs named including *Archaeopteryx*. And despite all this,
*Confuciusornis* in "spread-eagle" preservation along with other
dino-birds in this position, the femora are disarticulated. I still see no
evidence for laterally-extending femora 

R: Am not aware that anyone is arguing these birds could sprawl their 
wingless legs. Derived birds are often preserved on their backs or bellies 
because their bodies are flattened. That the deeper bodied Jehol dromaeosaurs 
are sometimes preserved splayed out unlike the similarly deep bodied 
Archaeopteryx suggests that the leg winged droms were able to sprawl their 
hindlimbs, unlike the winglegless Arch.

Note: It is interesting that even derived flightless dromaeosaurs often have 
a partial closing off of the acetabulem, which is also seen in some birds. I 
noticed this in the 80s but thought nothing little of it, is probably a 
retention of the earlier sprawling condition. 
 
<In all modern birds large, strongly asymmetrical distal primaries with
trim edges are always used for flight, display is at best a secondary
function. Since this form applies to the distal leg feathers the only
logical scientific conclusion is that they evolved primarily for flight,
and that display was at most a secondary use.>

  Yet there is no consideration of a display-exapted use for the original
leg feathers that enlarged them from a basal smaller, assymetry for air
foils? No. It seems *Microraptor* _must_ have flown.

R: Incoherent argument. If the leg feathers evolved from smaller airfoils 
into larger display-only feathers they would have lost the asymmetry, as 
occurs in birds when feathers are not used for flight (if anyone can point to 
a well documented case in which avian asymmetrical feathers are used for d
isplay rather than flight please let us know). The leg feathers of the winged 
dromaeosaurs were therefore used for flight. Since there is no evidence for 
the ability to flap the legs the leg feathers were purely for generating lift 
for pertinent purposes, they did not generate thrust. 

<If the dromaeosaur's leg feathers were the same size yet symmetrical then
it could only be concluded that they were for display. But this is not the
case, ergo arguing that aerodynamic feathers were mainly for display is
not logical of scientific.>

  Greg Paul bring to light many features in non-flying animals, such as
long pennate feathers in *Caudipteryx*, or large sterna in oviraptorosaurs
and dromaeosaurids, which must have been for flight, precluding that they
must be evidence for loss of flight. Unfortunately, possible evidence of
leg display feathers and a small tail airfoil with small wings in a
possible glider or flapper (which as I pointed out would be limited, not
"power flapping") seems to have been dismissed. Still, is the idea of a
flying and flapping *Microraptor* too much to look at other possible
conditions for the feathers. In the Hopp and Orsen hypothesis, these
feathers would also be in the perfect place for a brooding umbrella, and I
fail to see evidence of true flight.

R: Evolve fully developed, aerodynamicwings with associated skeletal and 
muscle adaptations for shade? Surely you pull our legs. 
 
<Since the foot feathers could fold up relative to the metatarsus,>

  What? I missed the muscular analysis showing the attachement of the
calamus to special dermal muscles (unknown in any other animal, as far as
I know) that would have controlled these feathers.

R: On the specimens the foot feathers are folded proximally relative to the 
metatarsus at an angle that would help them keep clear of the ground during 
normal ground locomtion. This may be a fixed posture. But that would make the 
feathers difficult to use for flight, or display for that matter. Of course 
birds can control the orientation of many of their feathers via dermal 
muscles. I postulate that this was true of the dromaeosaur foot feathers, 
which were not anchored to a flattened central finger as are the hand 
feathers. Need more specimens. 

<Biplane, for those having trouble with basic etymology, means two(bi) 
wings(planes). The arrangment of the wings is not definitive. There are
tandem biplanes, staggered biplanes, and so forth.>

  The term was "biplane" ... it was used by Paul onlist without the term
"tandem" or "staggered" attached when first used. I was refuting the use
of "biplane" alone. Tandem biplanes and the models I've seen show a
proximal smaller set than a rear, larger set, essentially variable
positions for canards, which replace tails. Few except Jim it seems have
suggested that the rear legs may have converged next to the tail, and this
would form a "convential" aeronautic design. No need for special designs
and circumstances, I think.
>>

R: Huh? Mostly incoherent. In any case biplane is biplane, it is not 
necessary to always describe what kind. The winged dromaeosaurs were biplanes 
whatever their form, or the position the wings were held in, when both wings 
were fully deployed. It is possible that they were mono/biplanes that did one 
or the other depending on the circumstances, like the pre WW II experimental 
Soviet fighter. 

It would be helpful if H would become more familiar with the data and be sure 
his writing is more understandable in order to avoid misleading folks. Then I 
would not need to spend so much time correcting the errors.  

GP