[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Lemurs and Feathers



In a message dated 6/20/01 10:58:43 AM, david.marjanovic@gmx.at writes:

<<>The problem with underwater flight is lack of fossil evidence.<

I'll ignore that, like everyone else does :-> , given that the Jurassic 
fossil record of pretty much all small terrestrial animals is extremely poor. 
>>

Yes, but those of us who don't ignore the fossil evidence just because the 
early Jurassic sucks, see a preponderance of evidence implicating a gradual 
theropod-to-bird transition. So don't count me among your "everyone else."

<<flight in air is apparently next to impossible with symmetrical wing 
feathers>>

I don't think even Feduccia went that far, did he? Symmetrical components can 
be assembled into asymmetrical structures. How does one PROVE that flight is 
impossible based on symmetrical feathers? I don't believe it. Boeing uses 
symmetrical rivets.

<<All recent flightless birds have symmetrical feathers, right? (In ancient 
Egypt ostriches were the symbol of justice because their wing feathers are 
perfectly symmetrical.) Same for *Caudipteryx*, right?>>

Y'know what? I'm starting to get really dubious about the use of the terms 
symmetrical and asymmetrical. Is the preservation of Caudipterix really so 
perfect that symmetry can be measured in its remiges to say, plus-or-minus 
1%? I sincerely doubt that ANY feather is 100.0% symmetrical. I've seen too 
many, and they're all curved left or right, and their barbs are longer or 
shorter on the left or right, simply based on which side of the body they 
originate from. Perhaps we should start talking about "subsymmetrical" to 
suggest, "effectively symmetrical" or some similar term. In my mind, the 
great debates about symmetry are pointless, because none of the structures 
under discussion are actually symmetrical. I'll say it again: integumentary 
structures are generally asymmetric.

Tracy Ford wrote:
<<So, when is the paper going to be out?>>
Dinofest 98? Never, I guess.
Our new one, maybe 6-12 months, depending on rejections, resubmissions -- you 
know, the usual.

<<In your theory brooding was first, so it goes back to the first theropods?>>
Some fish and invertebrates brood.

<<Would Coelophysis brood? Did all theropods brood or just some? (I know not 
all birds do, I think I heard that). So your telling us T. rex brooded? I 
can't see that large an animal doing it.>>
Here's how. Rex sits down near (not on) the nest, in the three-point posture 
seen in theropod trackways (two feet and pubic boot). Then Rex leans forward, 
balancing weight with tail until belly contacts rim of nest. Then Rex gently 
covers excavation/eggs/chicks with breast, puts arms in nesting-oviraptor 
posture, spreads feathers, gets tight seal. Heat from heart warms babies. Not 
that much different from the way Rex's second-cousin-twice-removed, Robin 
Redbreast, does it.


<<I've seen several other dinosaurs in a 'brooding' position, but because 
they aren't theropods brooding isn't thought about.>>
Yeah, there's a lovely Psittacosaurus from the Gobi that is in the oviraptor 
posture without a nest. I wonder if it could have applied that posture to a 
nest? Duh.

Thomas P. Hopp
Author of DINOSAUR WARS, a science fiction novel published by iUniverse
Now Humans are the Endangered Species!  http://members.aol.com/dinosaurwars