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Re:avian flight



My last message today -- please don't time me out... :-]
<<Can I send this to the list?>>
 
sure
 
<<Evidence? The size of lagosuchids etc.. I'm not speaking of *strict* insectivory (anteater-style) here, just the fact that today all small non-herbivores eat insects, and not of the size range of herrerasaurids.>>
 
I don't know how many insects you would need to eat to get enough solphures to be able to use it  to "build" modified scales,  but  I feel like something more specialized than a potentially, partially insectivorous diet by non strict incesctivorous animals should be needed.
 
However this is only speculation vs speculation since I  think nobody has tried to quantify this measure.( how much insects, given an individual quantity of solphures  for every single of them, would be needed)
Josef H. Reichholf has addressed this in one of his papers on this subject, and at least he wrote that modern physiology has the possibility to quantify things like that. I don't know whether he or anyone else has done this in the meantime.
        Anyway, I haven't clearly stated in my paper that birds with protein-poor diets such as parrots moult rather rarely and irregularly, while birds with protein-rich diets like clam-eating ducks moult rather often and shed lots of feathers at the same time. Often female birds invest some of their excess protein into the eggs which are large for vertebrate standards, while the males at the same time develop a display plumage that is later shed.
<<You know, most or all of the above is true, and yet it works in today's dippers (Cinclus), as I have mentioned, who are passeriforms (songbirds; they are called "water blackbirds" in German) and have, count them, ONE adaptation to their lifestyle, they can close their nostrils with flaps of skin that are unlikely to fossilise. >>
 
Something to say on this:
-these animals don't live in sea enviroment, right?(I'm asking since i don't know exactly, but they seem to be something similar to an animal I know and are probably the same); They live and hunt in little mountain rivers hardly comparable to an open sea.
Right. Archaeopteryx lived in the sea, but it is neither the ancestor nor the sister group of birds under my phylogeny...
They evolved this behaviour after  they evolved the ability to fly,not before;  being able to do what these little water blackbirds do needs very probably the ability to flight to be already present.(unless they hunt in too shallow little rivers for which high speed of penetration is not needed).
I've heard recently that dippers don't fly much when underwater, but rather walk on the ground perching on pebbles because their density is so low. This is not to be expected in more basal coelurosaurs, though, at least not in this extent, and after all, dippers do fly underwater. They obviously have evolved this lifestyle after the ability to fly; we only have negative evidence about whether the opposite is possible.
        A very big book (its original edition is English, but the original properties of it are not cited) about living vertebrates of the world mentions: "The 5 species of this family [Cinclidae, monotypic] are at home in Europe, Asia, North and South America, usually in highlands at fast-flowing mountain rivers. [No indication as what "not usually" is.] Among songbirds dippers are the only true water-living ones; in spite of this they don't have webbed feet [like Archie...] and as the only unambiguous adaptation to their watery milieu they have mobile flaps of skin over the nostrils which prevent water from getting in. Dippers can well dive and swim under water. They even can run over the river floor. The males are slightly bigger than the females." Then the Grey Dipper, Cinclus mexicanus, is described and figured. "Habitat: Mountain rivers; Length: 18--22 cm". There is a European Dipper, C. cinclus. That's all the information I have.
<<I should have added (or have I? I think I have) that Ebel proposes that the stiff, feathered tail of Archaeopteryx was for steering underwater (changing directions laterally would have been possible by rotating the tail, he writes; pelicans use their remarkably stiff tail feathers for steering when they're diving).>>
 
I think it would be interesting to know  how lenght of tail an body dimensions  are somewhat related in some way regarding this use of the feathered, stiff tail.
Yes... I fear there's only negative evidence for this, too.
<<Flying offers the advantage of being able to get to new fishing grounds fast and to look for fish from above, which tends to be easier.>>
 
This is an adaptation ( maybe, more precisely an exaptation if I've understood correctly the meaning of this word) of the already evolved ability to fly, not the selective pressure that led to it.
I think it's needed to distinguish these two things since they're really important.
This is the way exaptations work: an adaptation allows the animal to do something the adaptation wasn't designed for, and this use offers an advantage, even though that use is not necessary for survival, it is just an advantage (which leads to more food --> more offspring --> an advantage in natural selection). I think (see the Ebel paper) that this sort of underwater flight can lead to air flight quite fast.
<<it doesn't sound extremely likely, but more likely than ground-up and trees-down >>
 
I assume you say this only based on personal feeling   more than some kind of experimental evidence.
Based on the same(personal feelings)-but i think with some more empirical bases- I'm for the ground-up theory .
My personal feeling is based on the evidence I gave -- what is your evidence?
Ebel mentions a strong argument against ground-up -- chickens can fly but don't like to do so when unnecessary (I've posted this a few days ago) -- after he has debunked trees-down, of course.
 
:-)
 

I dunno, maybe rex just hunts at night, so Horner and company don't see them. :)
                    Larry Smith in http://www.cmnh.org/fun/dinosaur-archive/1994Mar/0046.html