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WHAT I SAW AT THE NATIONAL GEOGRAPHIC PART II



This Monday the Yixian feathered dinosaurs and birds at the National
Geographic were made available for direct inspection and photography. A fun
time was had by all. 

Sinosauropteryx - Direct examination confirms that the "croc-septum" described
by Ruben et al. 1997 consists entirely of breakage and glue. Where all three
arrows in their paper point, there is major damage. The ventral flakage is
especially hard to see in photos, the dorsal breakage is patently obvious. The
central crack was filled with cement colored to match the sediment. The
breakage occurred when the slab was broken into numerous pieces during its
initial removal by a local farmer, as a result the damage is symmetrical on
the two slabs. The repair work was also done by the collector. So Ruben et al.
mistook incompetent collection and repair work by an amateur for soft tissue
anatomy.  

What is the dark material? In Scipionyx the probable liver sits well forward
in the chest (as in birds), directly above the juncture of the anterior
gastralia and what must have been the posterior end of the cartilage portion
of the sternum. The authors of the Nature paper have confirmed to me that the
liver does not extend dorsally in Scipionyx, contrary to certain claims made
at Dinofest. In Sinosauropteryx the anterior end of the gastralia is well
forward of the dark material. Ergo, the liver very probably was not preserved.
The dark material is in the same location - the posterior half of the body
cavity from dorsal vertebra 8 or 9 back - as the well preserved intestines of
Scipionyx, so it too probably represents the contents of the gut. There is no
soft tissue evidence for the presence of a croc-like liver, septum, or fore-
and-aft partitioning of the body cavity in any theropod. 

It was suggested at Dinofest that the "body outline" (visible in the photo in
July Natl Geo) of the largest Sinosauropteryx lies outside and contains the
"internal fibers". The "outline" is actually the preservative applied after
the completion of prep work. In some places on the sediment the sealant is
thick enough to glisten (in most areas the coat was so thin that it absorbed
into the sediment with a flat sheen), there are some thick circular drip bead
marks, the brush work can be seen in some places, in some places there was a
shallow shelf of sediment where the brush did not carry the sealant into the
base of the shelf, etc. The sealant was applied to preserve the loose feathers
on the slab as well (as you can see in the Natl Geo photograph). 

In the Natl Geo photo, there appears to be an small array of feathers at the
tip of the tail of the large Sinosauropteryx. However, the slab was - as true
of all of these specimens - badly shattered, and the feathers lie on a
separate slab. At first glance there seems to be a couple of distal vertebrae
on the feathered slab. However, examination under magnification with a
flashlight revealed that no bone is present, the vertebrae are illusions
created by breakage of the sediment. The last few tail vertebrae are missing
because they were lost along with the slab that really belongs there. Nor do
the feathers have any connection with the vertebrae (unlike the tail feathers
of Protarchaeopteryx and Caudipteryx). They are just some loose feathers on a
slab that the farmer decided looked good at the end of the tail. The "tail
flipper" that some seem to think surrounds the supposed tail feathers is of
course just more brushed on sealant. 

>From what I gathered some who examined the specimens still belive that the
sealant is a body outline and that the tail flipper is real. Mistaking damage
and prep work is not, of course science, and one can only hope these
nonsensical notions will not see the light of publication. 

The tail of the largest Sinosauropteryx is much shorter, in both length and
count, than that of the much smaller type specimen. Makes one doubt that they
are the same kind of dinosaur.  On the other hand they share the same
distinctive hand morphology. 

Caudipteryx - On the better skeleton the profiles of the left ischium and
pubis are preserved as impression in the sediment. They are in full
articulation which each other and the left ilium. The pubes were barely
retroverted, they are basically vertical. The pubes were also extremely long,
probably to make the belly large in this herbivore. The ischia are similar to
those of dromaeosaurs, troodonts and oviraptors in having a large triangular
obturator process, the articulated ischium confirms that the dorsal edge lacks
any dorsal process. 

A running theropod evolving flight should have a tail no shorter and a sternum
no longer than Archaeopteryx, lack ossified sternal ribs, have arms longer
than other theropods, aerodynamically asymmetrical arm feathers, and be an
insectivore. Secondarily flightless birds have very short tails, large sterna
with ossified ribs, short arms, nonaerodynamic symmetrical arm feathers, and
are often small headed herbivores that use stones to help grind food.
Considering that Caudipteryx had all the latter features, it was probably a
secondarily flightless dinosaur related to oviraptorosaurs (the lower jaws are
very similar) that descended from fliers more advanced than Archaeopteryx. 

Protarchaeopteryx - A couple of weeks ago Andre Elzanowski and I agreed that
this is, as originally described, an Archaeopterygiforme rather than a
dinosaur. The short, broad sternum with an anterior indentation is a dead
ringer for that of Archaeopteryx, and all other skeletal details are
indicative of or compatible with this being a large urvogel. Question, where
are the wing feathers? If they were really not present then this creature was
flightless, in any case the arms are somewhat reduced so flight was not well
developed. Yet the tail is much shorter than that of Archaeopteryx. Prognosis,
descent from a flier more advanced than Archaeopteryx. 

Confuciusornis - Look Ma, no tail! The many complete feathered specimens lack
a well developed array of tail feathers (not to be confused with the hyper-
long pair of display feathers found on some specimens). The wings are large,
so this bird could fly, but not with much agility. 

GSPaul