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

Re: Archie a non-flyer? (was:Re: origin of bats/reply 2 to TMK)



What about the assymetry found in Archie's feathers? <<

Reduces drag. There are several viable activities archie could be doing where that would be useful. Remember, "aerodynamic" does not equate only to flight.



Scott Hartman Science Director Wyoming Dinosaur Center 110 Carter Ranch Rd. Thermopolis, WY 82443 (800) 455-3466 ext. 230 Cell: (307) 921-8333

www.skeletaldrawing.com


-----Original Message-----
From: Jean-Michel BENOIT <s.aegyptiacus@wanadoo.fr>
To: dinoboygraphics@aol.com; ptnorton@suscom-maine.net; david.marjanovic@gmx.at; dinosaur@usc.edu
Sent: Mon, 23 Jun 2008 12:13 pm
Subject: Archie a non-flyer? (was:Re: origin of bats/reply 2 to TMK)



What about the assymetry found in Archie's feathers?Â
Â
----- Original Message ----- From: <dinoboygraphics@aol.com>Â
To: <ptnorton@suscom-maine.net>; <david.marjanovic@gmx.at>; <dinosaur@usc.edu>Â
Sent: Monday, June 23, 2008 7:57 PMÂ
Subject: Re: origin of bats/reply 2 to TMKÂ
Â
Â
Alternatively, the phalanx proportions in Archie almost certainlyÂ
also allowed the digits to perform an aerodynamic function analogous
to > that performed by the alula in more derived birds.<<Â
Â
Almost certainly? In an organism that doesn't even preserve evidence
of > feathers on the thumb??? I'm not denying it's possible, but that's a > pretty strong statement considering the lack of evidence.Â
Â
If Archie flew from tree to tree, as I suspect, extending the manusÂ
digits during the high AOA phase necessary when approaching a target
tree > trunk would have aided in avoiding stall and placed the manus claws in the > proper position for grasping the tree trunk upon contact. <<Â
Â
And here, IMO, is the problem. You are assuming apriori that archie
a) > flew, and b) was arboreal. The former is debatable but a reasonable > stance, the latter is entirely without merit. Archie has basically no > characters associated with arboreality (its environment even seems to lack > trees) and in fact had several characters that would make it worse in > trees than less derived maniraptorans (notably the hind limb proportions).Â
Â
If you assume that archie landed in trees, then it sure seems like it
had > _better_ have an alula, but none of the specimens preserve evidence of > such. That could be an artifact of preservation, but not having an alula > would be consistent with the lack of a reversed hallux, the short length > of the hallux, the lack of strong felxor tubercles on the pes claws, the > long non-sprawling hindlimbs, the lack of pectoral musculature needed to > generate the force needed to oppose momentum during decceleration (p = mv) > and the lack of proper shoulder stabilization should such a maneuver be > attempted. Not even getting into the lack of a complete wing, etc.Â
Â
It may be that an arboreal component played a prominent roll in the >
evolution of avian flight, but if so Archaeopteryx was not involved.Â
Â
Â
Â
Scott HartmanÂ
Science DirectorÂ
Wyoming Dinosaur CenterÂ
110 Carter Ranch Rd.Â
Thermopolis, WY 82443Â
(800) 455-3466 ext. 230Â
Cell: (307) 921-8333Â
Â
www.skeletaldrawing.comÂ
Â
Â
-----Original Message-----Â
From: ptnorton <ptnorton@suscom-maine.net>Â
To: david.marjanovic@gmx.at; DML <dinosaur@usc.edu>Â
Sent: Sun, 22 Jun 2008 6:46 amÂ
Subject: Re: origin of bats/reply 2 to TMKÂ
Â
Â
----- Original Message ----- From: "David Marjanovic" >
<david.marjanovic@gmx.at> To: "DML" <dinosaur@usc.edu> Sent: Sunday, June > 22, 2008 8:23 AM Subject: Re: origin of bats/reply 2 to TMKÂ
Though let me quibble with a few details: Archie doesn't have longer
>> fingers than *Velociraptor* and clearly still used them for grasping
(judging from phalanx proportions, claw size, claw shape).Â
Â
Alternatively, the phalanx proportions in Archie almost certainly
also > allowed the digits to perform an aerodynamic function analogous to that > performed by the alula in more derived birds. If Archie flew from tree to > tree, as I suspect, extending the manus digits during the high AOA phase > necessary when approaching a target tree trunk would have aided in > avoiding stall and placed the manus claws in the proper position for > grasping the tree trunk upon contact.Â
PTJNÂ
Â
-- J'utilise la version gratuÃte de SPAMfighter pour utilisateurs privÃs.Â
Ce programme a supprimÃ5360 d'e-mails spam à ce jour.Â
Les utilisateurs qui paient n'ont pas ce message dans leurse-mails.Â
Obtenez la version gratuite de SPAMfighter ici: http://www.spamfighter.com/lfrÂ;
Â
Â