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

Re: Science feather strength debate

Agreeing with your opinion, as far as I am aware, as the bird humerus
is surrounded by muscle in a greater measure than the ulna, it is to
be expected that the plumage is not so firmly attached to the skeleton
at this point, and it may thus be more easily disarticulated with
decay. Correct me if I am wrong, but I never read or saw first-hand
humeri with feather knobs, while they can be found in the
carpometacarpus in addition to the ulna. If true, the lack of these
feather attachment structures may suggest feathers were not attached
to the humerus.

2010/11/14 Tim Williams <tijawi@gmail.com>:
> David Marjanovic <david.marjanovic@gmx.at> wrote:
>> Regarding life in trees, how good a glider can *Archaeopteryx* have
>> been when it had that gap between wing and body,
> I'm not wholly convinced that _Archaeopteryx_ lacked humeral feathers
> (= tertiaries or tertials).  Modern birds have three or four of these,
> proximal to the innermost secondary feathers.  However, no known
> _Archaeopteryx_ specimen exhibits feathers associated with the
> humerus.  For example, the flight feathers in the Berlin specimen are
> preserved on the distal forelimb right up to the elbow, where the
> feathers stop dead: no tertiaries.  This has been cited in support of
> the flight surface of _Archaeopteryx_ being discontinuous, with a gap
> between the wing and the body wall where the tertiaries would
> otherwise be (e.g., Garner et al., 1999 - the "Pouncing Proavis"
> model).
> However, two things make me skeptical about this interpretation.
> Firstly, some crown-group birds from the Messel are also found without
> tertiaries preserved, although the outer flight feathers are clearly
> preserved.  In these cases, the absence of tertiaries is certainly
> preservational.  So the same may be true for _Archaeopteryx_.
> Tertiaries were likely not as firmly attached to the wing as primaries
> and secondaries, and may have come loose.
> Secondly, Mayr et al. (2007) mention what could be evidence of
> tertiaries in the "Tenth Archaeopteryx".  They describe "marked, fuzzy
> furrows at the ‘elbow joint’ which may stem from the tertiaries".  As
> positive evidence goes, this is admittedly weak.  But overall, I
> wouldn't write off the possibility that _Archaeopteryx_ had
> tertiaries, and therefore the wing was complete, right up to the body
> wall.
> Cheers
> Tim