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

Re: avian flight/Underwater Flight

I'm going to respond to two messages here, so indulge me.
When landing on a tree, it is also very useful to have feet that can grasp a branch; I think Archie would have slipped in this situation because its halluces were too far up the foot.<
I think that you are right here. However, I was refering to a situation where it would use this mechanism to land on the ground, where it wouldn't have to worry about missing or slipping of a branch.

Cats flap? All I know falling cats do is they turn themselves around so that they land legs-first. And cats have legs quite different from Archie's...<
Yes, you're quite right, I should have made this a little more clear. I meant that moving the limbs while in free-fall is a common reaction, to flapping. After the cat is facing the right way (feet down), it still moves it limbs around a bit. This is what I was refering to.

True. Well, maybe Archie dropped into the water head-first from just above the sea surface...<
Possible. But this would require slowing down, so that Archie didn't crush his skull. And if Archie can slow down above water, why not slow down above land?

Completely true. Therefore, once more, I use HP Thomas Hopp's hypothesis
that wing feathers evolved for brooding. First wings, then flight, not both at the same time.<
Okay, cool. I understand that part now :)

Yes. See above. I don't think any animal would glide from a tree to the
ground and then climb up the next tree instead of directly gliding there.<
This assumes that Archie would immediately want to get into the next tree, instead of stay on the ground, where it could hunt during the day (or night, whichever it may be), and then return to the trees so it could sleep in safety. It would then glide/fly down from it's perch the next morning to resume its hunting.

Just that I didn't say that *Archaeopteryx* was insectivorous. I think I
have stated quite clearly that IMHO it was mainly piscivorous. Plenty of
fish of the right size, like *Leptolepides*, were around. (Of course, I
don't say that Archie would have refused to eat one of the 10-cm-long
grasshoppers that have been found there -- if it could catch one.)<
Okay, cool. I must have missed that part of the paper, sorry. That would be an advantage, yes.

BTW: Solnhofen with one e in total.<
Right, thanks. :)
Then, from Underwater Flight:
I (unlike Ebel) also suppose that wing feathers were already present.<
Animals of Archie-size, however, which never became fully aquatic and still
used their wings in brooding as well as for locomotion...<
Okay, this becomes a little clearer, now. However, I think the push to lengthen the feathers (brooding), would be somewhat (not entirely) canceled by the push for small feathers (hydrodynamics), the end result would be feathers that couldn't be used for flight or gliding. You said the flight would evolve as a response to flying from fishing ground to fishing ground. It's my impression that it's much harder to take off from the water than from land (or from a tree). Just watch a goose gently leap into the air from the ground, as opposed to having to sprint on the top of the water for some distance before it becomes airborn. This would take some well developed legs (the impression that I'm under. Anyone know anything about the legs of geese?). Now, does Archie (or another early bird) have the leg structure that would be needed to take off from an aquatic environment.

It fits the hypothesis that dinofuzz/protofeathers is a synapomorphy of
Ornithodira or so, which bases on the assumptions that pterosaur fur looks
like feather shafts and that endothermy is a synapomorphy of Ornithodira
too. All unproven, all more or less testable.<
Okay, cool. I don't necissarily belive that this is the case, but it is a really intersting idea, so I try to examine it more. Hey, I drew a feathered _Zuniceratops_ based on that idea, so at the very least, it can give some cool pictures!

If they were not sauropodomorphs, which is current consensus and
quite likely, well, then, you'd expect feathers on the sister group of
Yeah. I'm under the impression that they are theropods too (really odd looking ones), and knowing nothing about them, I will defer to people more knowledgeable about them.
By the way, I must say that your paper is quite interesting! Sorry if it seems like I'm out to destroy your hypothesis (even if it may seem I'm not succeding), but this is not the case. I've heard the arguements for and against trees-down and ground-up, but since I've never heard this idea before (I will have to get Ebel's paper), I'm providing myself the opposing view. Based on your comments and my thoughts, I'll end up forming an opinion of the theory. So...I'm not out to get you, I'm just trying to theoreticaly test your hypothesis!

Student of Geology
Northern Arizona University
P.O. Box 20840
Flagstaff, Az. 86011
AIM: TarryAGoat
"A _Coelophysis_ with feathers?"

Get your FREE download of MSN Explorer at http://explorer.msn.com