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Re: weird jurassic dinobird with very weird feathers
David Marjanovic wrote:
<Forgot to mention that I don't have the book here that describes
*Scansoriopteryx*. What does its tail look like?>
The proximal 20 or so caudals are preserved, which increase in length
distally until the final four or so, which begin decreasing. Relative to the
hip, I'd estimate the sequence in *Epidexipteryx* should start about where the
sequence in Scan ends. This implies a potential caudal length of 26+ caudals,
with a discontinuity in doubt between the sections.
<Neither are any other feathers or any other soft parts preserved on any of the
limbs. The whole ventral side appears to lack preserved integument or other
soft parts -- and the color of the sediment there is different. IMHO we're
dealing with absence of evidence here rather than evidence of absence.>
There appears to be a dark mass in the body cavity, a light greyer mass in
the pelvic region, and then the darkened mass dorsal to the skeleton.
Extra-integumental fibres appear to extend from the hips down the femur and may
arise from the tibia, implying the limbs were "fluffy", but they may not have
included the tail. Since *Scansoriopteryx* preserves reticulated squamation on
the tail, it may have been naked. so why "feathers" on the tail? They may have
arisen from loss of the tail "fuzz", but it's also likely they persist as part
of a dorsal caudal fuzziness. They appear to have a "rachis" and it seems to be
hollow. While this does not argue for pennaceous feathers, it doesn't support
the body having them. The preserved fibres are virtually identical to those of
*Beipiaosaurus*. The dorsal "halo" does not correspond to the body margin,
which may have been moved during fossilization, but neither does it correspond
to the arm, which overlies a
critical region of preservation. One should think if the arm were heavily
"fuzzed" up, you'd see some sensu *Beipiaosaurus*, *Yixianosaurus*, NGMC 91,
etc. This implies either 1) disarticulation after the halo was "imprinted"
(unlikely), or 2) lack of pennaceous feathers on the arms (where they'd most
likely be, aside from the tail, which similarly lacks any OTHER form of
"fuzz"). Tricky, eh?
This gives me the impression of a decourously-tailed "monkey" animal with
short furred arms and long "hairs" on the neck and back which may have been
mane-like, sensu the maned wolf (yes, it's a fox, I know).
<Not true. In *Epidendrosaurus* the claw of the 3rd finger is considerably
smaller than the other two.>
Okay, I may have gotten the unguals mixed up somewhere: The holotype of
*Epidendrosaurus* appears to show mdIII-4 and mdII-3 of approximately the same
size, as it is in *Scansoriopteryx*. So this may be a matter of switching the
unguals. However, the unguals are not "considerably" smaller, since there is
only one ungual of any size (and only in Epi's type) of a size differentiated
from the others (implied to be the pollecial ungual).
Jaime A. Headden
"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)