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Re: Theory on ornithoptering and could Archie do it ?




<<Well from the information that I've gleamed off of sugar gliders...>>

    Do you happen to own sugar gliders too?

<<and draco lizards, it seems that they glide from tree to tree for two 
main reasons:

1: It's the fastest way to get from point A to point B

2: It is a highly effective way of avoiding predators.

Both of these animals don't seem to capture food by gliding. In fact 
when one thinks of it, gliding isn't the best way to catch insects.>>

     Hold up.  Sugar gliders in the wild can glide up to 300m and can 
catch insects in mid-air and the dark ( this is the way that they catch 
the majority of the their insect food since they do not have a 
chameleon-like tongue ).  Your points #1 & #2 are very good points and i 
suspect that #1 has the most to do with the problem.  

<<Think about it. A glider needs the momentum of their falling bodies to 
keep them going. Some like dracos are efficient at turning and keeping 
airborne for a long distance. But the insects that a glider would chase 
are powered flyers. Many insect flyers like bees and flies are not only 
very fast, but very agile too. >>

     Sugar gliders depend on the momentum of their bodies to keep going, 
yes,  but they also have some huge skin folds and an airfoil shape to 
gain lift and distance ( as well as the height of the tree that they 
jumped off of ).  Sugar gliders are also great at maneuvering.  Mine was 
crawling around somebody and it jumped to me, I, oblivious,  ducked down 
to grab something, and she glided right over me.  Since she was heading 
for a bookcase, she performed a miraculous turn and only lightly tapped 
the bookcase and fell to the floor.  Sugar gliders have to be good at 
turning to be able to catch their insect prey and to land on flowers.  

<<That's the problem with chasing an ornithoptering insect. They have 
that nasty habit of zig zagging and darting in all kinds of weird 
directions. As a glider your running on borrowed time, these insects on 
the other hand (by ornithoptering) are making their own time. Doesn't it 
make sense to find a better way to chase them.>>

     Of course this is assuming that basal birds chased after insects.  

<<What if that Archaeopteryx that flew down from the tree and just 
missed that darting dragonfly, turned around and, with some short flaps 
to regain speed, went after it again.>>

     Greg Paul has discussed the prospect of Archaeopteryx as an insect 
chaser and he came to these basic points:

1)  Archaeopteryx could not live on the diet of just insects because it 
was too big to support itself on just insects ( and let me point out 
that even if it was bradymetabolic,  this would still hold because the 
larger size of Archaeopteryx compared to >most< other insectivores still 
holds ) and that there cannot be given that there would be enough 
insects availible for Archaeopteryx.  
2)  Insect flight is comparable to WWII Spitfire flight whereas 
Archaeopteryx flight is comparable to a slow, early Wright flier. 

<<I'm not suggesting a complete ornithopterer here, but just the 
occasional flap to help it keep up the chase. This occasional flap would 
no doubt show up as a benefit and the evolution of powered flight 
commences.>>

Archie's body is not streamlined like the body of sugar gliders for 
example.  Sugar gliders are compact even during gliding.  

<<Now from what I've heard Archie is missing that enlarged sternum for 
it's wing muscles, so it is said that it can't fly.>>

Arcaheopteryx bavarica has an ossified sternum and as I pointed out 
previously on the list,  Archaeopteryx seems to have most of the 
osteological and myological improvements for flight. 

<<Even a weak flap, could be an advantage. Especially when trying to 
keep up with a fast moving insect.>>

Plus, if early bird flight was concentrated on banking, then the wings 
would have a greater amount of movement than seen in Archaeopteryx.  

I applaud the originality of this theory ( Ostrom proposed something 
like this for the cursorial origin of bird flight,  but it is different 
) and even though I find it flawed,  keep 'em coming!!! It was a pretty 
good idea.

Matt Troutman

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