Re: Tail feathers

["James R. Cunningham" <jrccea@bellsouth.net>]

Matthew Troutman wrote:
snipped
> Wellnhofer (1991) has reconstructed the pterosaur
> myology for the flight apparatus and he has concluded that though it is
> different from bird myology in some small details, it is overall very
> similiar.

It is similar in many ways, but just as different in many others.

> Pterosaurs also have a pteroid bone that supported the
> brachipagatium,

Propatagium.

> which would have functioned much like the alula in
> birds.

No. Wrong location and the pteroid was submerged. The pteroid provided a
bit of a Kruger flap function at the leading edge, but that doesn't
appear to have been it's primary purpose (a tiny bit of leading edge
deflection goes a looong way). The alula function was provided by the
small fingers at the distal end of metacarpal IV.

> The fiber-supported membrane was similiar from that of the avian
> wing because each of the fibers supported like feathers.

No.  The fibers were crucial to the flight performance of the pterosaur
wing, but there were no similarities whatever between their method of
operation and those of feathers.  Bear in mind that feathers can
withstand longitudinal and torsional bending moments and can carry both
tension and limited compression.  The pterosaur fibers could carry no
bending loads, only tension, which is part of the reason for the distal
bend in the metacarpal which functioned to alleviate spanwise tensile
stresses. The spoon-shaped joints between ph 1&2 and ph 2*3 served the
same purpose. One of the most fascinating things about the pterosaur
wing is the mechanism for gust load alleviation, since the flexible
membrane could not directly apply torsional loads into the skeletal
spar.  This mechanism is particularly elegant in Azhdarchids.

> 
> CHIROPTERANS
> 
> (If I can get any answers out of this question I would be rather
> surprised.)  Does anybody else think that Chiroptera is diphyletic as
> supported by Pettigrew and others?  Though I do find the analyses of
> Simmons and Novacek very interesting and compelling, I am intrigued by
> the similiarities that Megachiroptera shows to Dermoptera and Primates
> (mostly the neurological similiarities) and not to Microchiroptera.
> Anybody want to concur or disagree?

Try Harry Erwin.  I'm impressed by initial communications with him.

                                JimC