Re: origin of bats/reply 2 to TMK

[dinoboygraphics@aol.com]

> > 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.<<

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.

> > 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. 
<<

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).

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.

It may be that an arboreal component played a prominent roll in the 
evolution of avian flight, but if so Archaeopteryx was not involved.



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: ptnorton <ptnorton@suscom-maine.net>
To: david.marjanovic@gmx.at; DML <dinosaur@usc.edu>
Sent: Sun, 22 Jun 2008 6:46 am
Subject: Re: origin of bats/reply 2 to TMK


----- Original Message ----- From: "David Marjanovic" 
<david.marjanovic@gmx.at>Â
To: "DML" <dinosaur@usc.edu>Â
Sent: Sunday, June 22, 2008 8:23 AMÂ
Subject: Re: origin of bats/reply 2 to TMKÂ
Â
> 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
Â
PTJN Â