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WHAT I SAW TODAY AT NATIONAL GEOGRAPHIC
Today I had quite the thrill of attending a historical event, the public
unveiling of fully feathered Chinese dinosaurs.
The main presenters were Ji Qiang, Phil Currie & Mark Norell. Also attending
were John Ostrom and Alan Brush. The July Natl Geo and June 25 Nature cover
and describe these fossils.
The two critical creatures were Protarchaeopteryx (one moderately good
specimen, skull present but too damaged to restore) and Caudipteryx (two, one
moderately good, the other very good with well preserved skull).
Both are peculiar theropod dinosaurs, quite advanced and bird-like (far more
so than Sinosauropteryx). Skulls small and short in both. In both the complete
tail is quite short, proportionally more so than in Archaeopteryx (although
vertebral counts are not lower). Caudipteryx in particular seems to have
affinities with oviraptorosaurs, including the skull. Yet is has many
differences as well, a real mosaic animal. Hindlimbs are extremely long in
both; these were clearly runners. Both are fairly large, as big as a turkey.
Claims by Martin (see below) and Feduccia that these are birds are incorrect.
There are no avian skeletal features, many dinosaurian ones. Jugal is robust
and triradiate. Quadratojugal contacts the squamosal. Coracoid short and
broad. Ilium deep and subrectangular. Ischium lacks dorsal processes. Fibula
reaches the calcaneum, which is seperate from the astragalus. Metatarsals are
unfused. First toe is rather proximally placed and unreversed.
The reason that Martin & Feduccia want these to be birds is because of the
feathers. In both large fans of long, fully avian type contour feathers
radiate from the last few tail vertebrae.
In Caudipteryx long primary feathers are anchored on the hands. These
structures have the characters expected in complex bird feathers. Both have
the Sinosauropteryx type bristle feathers on the body. (BTW, psittacosaurs
from the same sediments have preserved scales, not feathers.)
The unsubstantiated nonsense that the fibers on Sinosauropteryx were internal
collagon is of course refuted - again! Reality, theropods had feathers both
simple and complex (how far back in theropods feathers go is now the
question). Feathers no longer define birds. Indeed, as Padian emphasizes in a
note in the Nature issue, most of what used to define Aves is now found in
dinosaurs. It is now clear that the body covering of bristle feathers evolved
as insulation, in that they thermally isolated the body from external heat.
Ergo these were not ectotherms that relied primarily on the environment to
provide internal heat.
It is the large arm and tail feathers that pose more of a question.
The arms of Caudipteryx (rather dull name - but easy to spell!) are very
short, much too short to fly with. The primary feathers are asymmetrical,
which is not highly aerodynamic. Both forms appear to have been flightless.
The describers place these theropods less close to modern birds than
Archaeopteryx, and before the advent of flight. Of course this is possible.
However, I suspect these are secondarily flightless dinosaurs closer to birds
than the urvogel. Consider some features one might expect in a secondarily
flightless dinosaur, one closer to birds than Archaeopteryx. A shorter tail,
perhaps stiffened in the manner of pterosaurs, to better control body
orientation during flight. Large sternal plates and ossified sternal ribs, to
support a flight musculature, and help ventilate high capacity lungs. Well
primary & tail feathers
, symmetrically altered from
larger, symmetrical flight feathers. Caudipteryx has all these features. Andre
Elzanowski has shown that the oviraptorosaur palate is more avian than that of
Archaeopteryx. These dinosaurs could be early "ostriches", in that they
evolved from fliers to become fast running, fairly large land herbivores
(indicated by the presence of large bundles of gizzard stones in both
Caudipteryx specimens), reducing the arms along the way. What were flight
feathers were modified into display surfaces.
A lot of press was there, NBC & CBS news briefly covered the item, NPR had a
nice piece on All Things Considered. Except that on the latter Larry Martin
made a comment something to the effect that 'although it makes for a more
exciting press conference to say that these are feathered dinosaurs rather
than early birds, he was sure that more reasonable consideration will
eventually show that these are birds'. Martin has yet to see these specimens,
unlike Currie, Qiang & Norell who have carefully examined them and described
the dinosaurs. I leave it to you to judge who was trying to make an
unjustified - and insulting - splash with the press.
After the conference Ostrom - who has had the joy of seeing his notions
verified by the fossils - turned to me and asked if I thought it had been an
important even. I replied that we just saw history in the making.
On a related matter, the age of the Yixan beds is still up for grabs. Most
important, two long tailed pterosaurs have been found, these are otherwise
limited to the Jurassic. For that matter, Sinosauropteryx is a compsognathid
of Jurassic type. The beds may be very early Jurassic in age. Leaves me
scratching my head as to where the birds are in the Solnhofen.
The specimens, plus two Sinosauropteryx (incl type) and Confuciusornis will be
on display at the Natl Geo for a month. Your big chance to see them in the