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Re: Cost in Aquatic Birds (long)
David Marjanovic (email@example.com) wrote:
<Almost. The only positive evidence I can hope for are fossilized skin
flaps on the nostrils... bit improbable :-]
Well, so far I think all other explanations for the wingstroke are even
more improbable than FUCHSIA, and just as behavioral and testable
respectively not, and assumed to have taken place at the same time where
the fossil record is meagre in general. :-)>
... and ...
[in regards to competing theories on wingstroke evolution]
<I can think of
- a glider suddenly starting to flap out of nowhere. Improbable and
- a terrestrial winged theropod jumping and flapping around for display.
It may be a bit hard to explain the evolution and then retention of the
ability to fly in a cursorial animal... and it's just as behavioral and
untestable, if not slightly more so.
- Vertical running. Sounds interesting to say the least, but I haven't
seen the SVP talk, or any video of a bird doing that, and am waiting for
the paper. =8-]
- I'm pretty certain I've missed some... I appreciate suggestions.
Really, if they are more testable than FUCHSIA :-)>
You take a decidedly reductionist viewpoint here. Now, note that I (as
I've said previously on similar threads) hold no specific theory to be
true. I note, however, that the effective data and record for some
theories holds better water than others. This is based on testability,
however limited, even if all it affords is the ability to look at the
Positive data exists for several theories, including the Hopp and Orsen
brooding hypothesis [HOBHY, or "hobby"] which posits the wingfolding and
feather assymetry are effective by arm position over nests and broods.
This is very friendly to the display theory, possible as comparative
adaptational responses in a single ecosystem; there is the BCF theory, in
which wing and arm structure are descendant features as a result of a
primitive arboreal nature of theropods (this is possible given some
features of *Eoraptor*).
<Can "reduced" and "incipient" be told apart?>
Depends on the existence of the condition in earier forms or later.
Reduced as in regressive, from a preexisiting condition; incipient as in
formulative to a more derived condition where the morphology is, however
derived) present. These are temporal comparables and require a fossil
record for comparison mapped on a phylogeny (phylostratigraphy). More on
<And _THIS_ <trumpets> is what I imagine basal Eumaniraptora
(Maniraptoriformes of most others by content) did for a living. For maybe
the tenth time, I don't think Archie or any other known non-ornithuran
dinosaur was aquatic in the full sense of the word>
<And once such an animal got crazy, folded and unfolded its wings again
and again, faster and faster, and suddenly found it had lifted off? :-/ --
In water such a behavior might even be adaptive :-)>
yeah, except that it requires a precise coordination that must be
produced through effort within the medium. The data evidences that the
power stroke was produced _after_ the animal was airborn. *Archaeopteryx*
and *Confuciusornis* lacked this quality, and Enantiornithes and
Ornithurae attained the capability convergently.
<My incitation for using FUCHSIA at all is that there is a difference
between having the ability to flap and using it for flight; these need to
be explained separately.>
No one tries to put them together. Flapping (or the ascent-descent
humeral stroke), the power stroke, aerialism are all separate qualities
that have been demonstrated in other theories. One such is the predatory
strike in the ground up hypothesis; which has been adapted in Chatterjee's
<Yep. But it is the best-supported scenario so far. (I only know 2 others:
one is the classical arboreal theory that starts with gliders, the other
explains the evolution of wings [as solar panels] but not that of
How, o how can it be supported without any positive data?
[on my use of "near-shore paravians" as antecedent to the avian
<You mean the pretty long hallux of *Microraptor*? Hm. It's still shorter
than in perching birds (and most ground-living ones, for that matter) and
is apparently attached rather high on the metatarsus (as Archie's). We
need better articulated fossils to get more clarity here, and less crushed
ones to tell how reverted that toe was (same for Archie).>
I mean the general nature of elongate arms, large manal [first stem is
manus, hence man-, not manu- then manual, at least from my understanding
of the situation ... I am hardly the first to use this, it is common in
European work, and among the westerners, Dale Russell is consistent in his
usage -- trends stick] claws, galago-like brachial structures from the
integument (feathers and the like are not integument (skin, hide, bones in
the hide, etc.) but are extra-integumental (reptile scales, feathers,
hair)), balancing structures and typical arboreal features. I posit
*Microraptor* as a possible twig-hugger, but my concept did not include
this animal specifically.
<<were predicatory to the flight-stroke.>>
<I don't understand what you mean by predicatory. My (not very big)
dictionary only connects it with preaching.>
Of or involving prediction, or indicating things that come before
<There's one big argument against ground-up... ground-living birds fly
rarely if they still can. Roadrunners almost never fly,>
I would disagree. They [roadrunners] are very flight-capable, and have
seen them occasionally take to flight while taking on or pursuing prey --
in this they are very similar to crows and other corvids -- they just
spend much of their time on the ground. Same for tinamous. Some birds
despite their terrestriality can still be operative fliers and are not
untile in these scenarios. Fowl are a good examples of increase in true
terrestriality in a flight-capable species; body-mass : wing loading
ratios increase so that the animal's weight becomes detrimental to its
flight performance. Increase in herbivory in birds has a tendency to do
this. Terrestrial predator birds like *Geococcyx* and *Sagittarius* are
still quite aerialists, and both mate on the wing, whereas fowl typically
do not. It is true that both favor near-land perches, but so do most
<Information includes as a character, is whether it has an extra exit for
V1. Currently having one unites Tyrannoraptora without dromaeosaurs +
My look at the material (photo and drawing) appears to suggest not. An
expanded opening for the trigeminal so that the first branch of the nerve
split within the bone or at the apse, or the lack of this condition to
begin with, is not something we can tell for now.
<<The absence of serrations, as I hope to show soon, [...]>>
and David replied:
<Is there a paper to wait for? :-)>
At some point in time, hopefuly so. Presently, research is preliminary
and I will be presenting occasional reports as the work goes on. Teeth are
fascination structures, and horribly prone to convergence; they are the
quintessential form-follows-function structure in anatomy.
Now, for the big part:
Absence of testability is the flaw here. FUSCHIA cannot be tested, only
conjectured. It is not even a theory, but an hypothesis. Particulate to
the theory of the origin of flight is the application of the concept to
the fossil record, and in this, some other theories provide _some_
BCF -- small theropods lived in trees, produce limbs and grasping
structures and "typical" theropod qualities as a result of their
arboreality, leading to thye preclusion of Aves to develop flight-worthy
limbs. Birds have such structures only as a result of their ancestry, and
thus, birds came first; an increase in terrestrial motive for early
theropods precipitated loss of the small features in basal dinosaurs and
theropods, but most theropods retain the essential complex developed early
Evidence: small basal theropods have semi-stiff tails, large toes, long
arms, and triangular skulls, adaptational in some ways to arboreal life.
Grasping manus may have led to the power stroke in other theropods. E.G.,
*Eoraptor* and *Herrerasaurus*.
BAMM -- two competing qualities: AFIT [arboreal flying in theropods],
and THATF [theropods are terrestrial _first_]. The first has theropods
clamboring in the trees and begin to leap from one branch to the other,
developing primate-like crania and arms to better live in a
fully-three-dimensional world; these are predicate to leaps to farther and
farther branches, until they are jumping from trees to spaced trees, then
start gliding, and in the effort of controlling the flight, develop the
flapping capability, and refinement produces the power stroke.
Evidence: fossils indicate arboreal maniraptorans were flightless and
more primitive than birds, but had many features that equate to the
development of incipient gliding; basal birds could not use a power
stroke. *Sinornithosaurus* looks fairly galago-like and may have easily
leaps from branch to branch and between trees. Hair-like rachis and barbs
develope as an effect of primitive structures being influenced by drag.
Fossil succession is indicative of an increasingly complex arboreal and
leaping complex. The glider is not in evidence as of yet.
The second theory holds that the long arms are prey-capture tools and
that development of the prey-capture strategy produced the predatory
strike. Display or brooding may have produced the feathers that were used
Evidence: *Caudipteryx* is clearly terrestrial, and the development of
structures in maniraptoriforms indicate that the arm was modified without
special "hair" or "protofeathers" from compsognathid to bird. Thus, flight
and the development of the feathers were not neccessarily related.
Brooding and display hypothesis are also compatible with this concept.
BAND -- small arboreal reptiles ... nuff' said.
Evidence: *Longisquama* has thoracic structures resemblant of feathers
that suggest that avian features segmented and became complex.
*Cosesaurus* suggests a complex of feather-like structures in similar
animals, and the arms appear to be precipient to avian-style wings. Use of
*Megalancosaurus* appears to preclude avian-morphology in the trees.
*Caudipteryx* was a bird, not a dinosaur. Theropods were cold-blooded.
There is clear evidence for each theory, despite claims to the contrary.
Problem is, the ground up or the trees down theories are not particularly
compatible, and involve much of the same data. One involves the fossil
record more than the other, wheres the other relies on anatomy more. BCF
needs fossils. And BAND is just ... each taxon is simply misrepresented.
FUSCHIA adds no data that can be seen that actually allows it to be
tested in light of the competition. It relies on a problematic comparison
between fossil "protoavians" and modern birds, despite the lack of
behavioral data in the former and no osteological correlates in the
latter. Modern birds, though admittedly derived, compare well with other
aquatic forms that indicate developing propulsive mechanics leads to a
nearly permanent aquatic life, and that use of adaptations to swimming do
not tend to develop in non-aquatic animals. Few animals learn to swim from
a non-aquatic form, then become terrestrial or aerial again. Thus, there
is sufficient data to contend that FUSCHIA adds no useful data to the
discussion, as I see the situation.
Jaime A. Headden
Little steps are often the hardest to take. We are too used to making leaps
in the face of adversity, that a simple skip is so hard to do. We should all
learn to walk soft, walk small, see the world around us rather than zoom by it.
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