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Re: Tail fans and Jurapteryx
On Sat, 6 Mar 1999, John V Jackson wrote:
> --Original Message-- From: Pharris Nicholas J : Saturday, March 06, 1999
> 10:26 AM
> >I think a good tail fan is what is missing from feathered dromaeosaur
> >reconstructions. _Caudipteryx_ has one, _Protarchaeopteryx_ has one,
> >Archie has one (and _Jurapteryx_, which I still bet is actually a
> >different taxon--the arms and back are shorter, the tail and legs are
> >longer, the skull is bigger, and the pattern of feathers on the tail is
> >different from in _Archaeopteryx_.
> Sounds interesting Nick. Are these certain examples of Archaeopteryx? If
> so, which ones?
About as certain as one can get, since they include the type specimen,
BMNH 37001 (the London specimen). The Berlin specimen, HMN MB. 1880/81
also appears to be a good _A. lithographica_. However, the Eichstaett
specimen, JM SoS 2257, was singled out by M. E. Howgate in 1984 as the
type specimen of _Jurapteryx recurva_. It is a more gracile animal than
_A. lithographica_, and it has been interpreted as a juvenile
_Archaeopteryx_. However, using Greg Paul's figures from PDW, though the
total length of _J. recurva_ is only 71.6% of that of _A. lithographica_,
the skull is 86.7% as long as archie's, and the hip height is 80%. Hence,
there are some serious proportional differences between the two. Paul's
reconstruction of JM SoS 2257 is, I think, too short in the tail.
I have read indications that the teeth differ as well. The second toe of
_J. recurva_ appears to be somewhat shorter than the fourth, while in the
Berlin specimen the two are subequal in length. The form of the pubic
boot also appears to differ somewhat.
So finally we come to the feather differences in the tail. While the
London specimen clearly shows a large, elongate tail fan, expanding
towards the back and kind of squared off at the end. The length of this
tail fan is about 3.2 times its maximum width.
The margins of the feather impressions around the tail of _Jurapteryx_, on
the other hand, are parallel, which is why I say the tail looks more like
a ribbon than a fan. Moreover, the length of the tail with its fringe of
feathers is over *5 times* its width.
Pacific Lutheran University
Tacoma, WA 98447