Confuciusornis [was Re: Thanks : postcranial]

["John V Jackson" <jjackson@interalpha.co.uk>]

--Original Message--From: siriraks arrathrakorn <arrathrakorn@yahoo.com>16
November 1998 09:42



>Thanks you for your information on postcranial skull but I still not
>know why postcranial structure is importance for climbing tree trunk.

Archaeopteryx had big strong arms and claws which it could use to climb tree
trunks.  Other small theropods such as Compsognathus and Sinosauropteryx
have very small arms.  They could have climbed with them, I guess, but they
couldn't have glided with them.  Also Archae. could hyperextend the second
toe, which it could use to press in against a trunk trunk.  Archae. also had
a stiff tail that could be pressed against a tree-trunk as woodpeckers
(piciforms) do.


>Information about confuciciusornis in NATURE are not yet clear.
>Would you please tell me some information about this or how can I find
>it?

Hou L-h, Zhou Z, Martin L.D, Feduccia A. "A Beaked Bird from the Jurassic of
China" Nature vol. 377 pp616-8, 19 Oct 95

This appears to be the official announcement of _Confuciusornis_ (sanctus).
The first beaked and the first toothless bird. The arm bones were beefier
than in _Archaeopteryx_. The tail was not known at that stage and was
depicted as about 2.5 times longer than it later turned out to have been.
(The same authors in order Hou, Martin, Zhou & Feduccia, published "Early
Adaptive Radiation of Birds: Evidence from Fossils from Northeastern China"
Science vol. 274 15 Nov. 96, showing the proper tail length - less than a
quarter of _Archaeopteryx_'s).

In both papers _Confuciusornis_ is put just outside the Enantiornithes, on
its own, but closest to _Gobipteryx_ (which they describe as
enantiornithine, but which they put on a distinct prong of the "Nature"
cladogram, but since the rest of the cladogram is to my eye a million miles
away from reality...).  However, _Conf._ does seem to have the three things
my as yet inexpert eye has come to associate with enants: hugely expanded
proximal (ie near the centre of the body) end of the humerus, with a big
dent or hole in it; fusing of the metatarsal (the bit between the ankle
joint and the rest of the foot that in humans is hidden within the foot) at
the proximal end, instead of at the distal end as in modern birds; and of
course, no uncinate processes - hooks between the ribs, which modern birds
have.

_Conf._ is from the Yixian Formation - that is the earliest of the
bird-carrying deposits known from China.  It is often said that the dating
of the Yixian is controversial - J or K? but on reading this paper, it seems
to me, the main controversy is where we decide to put the J/K border.  the
Yixian seems to be about 140 myo give or take 5 (roughly combining two
dating methods).

The authors often referred to _Conf._ in the "Nature" paper as the "Liaoning
Bird" - presumably what they called it before plumping for _Conf._ .
However they report in the Science paper _Liaoningornis_, which is the
oldest (as far as I know) example of ornithurine birds within which modern
birds are placed.  This is only 10mys after _Archae_ - or maybe just 3 or 4.
As the authors suggest, one explanation is a v rapid evolution
post-_Archae_., though by the "Science" paper they have decided the
differences between the enants and the orniths is just too great for archae
to have been the first bird.  I agree with Chiappe though; evolution can be
that fast in very special circumstances.  I would be interested to know how
many small pterosaurs are found in the China deposits.

The next oldest known ornith bird was at that time _Chaoyangia_ (early K),
with its feet suited to wading.

Spanish Early K enant birds included: _Iberomesornis_, _Concornis_,
_Noguerornis_ & _Eoalulavis_.  They were sparrow-sized.

Chinese EK enants included _Sinornis_, _Cathayornis_ & _Boluochia_.  The
ornith. _Gansus_ accompanied them.

They said the late J birds were bigger than the K birds.

Oh.  They also said towards the end of the Science paper: "... This temporal
paradox has led some dinosaur experts to argue that birds gave rise to
certain Late K theropods [GPS: "Predatory Dino.s of the World]".  The way
they didn't disagree with this makes me think they may have been giving it
some thought.

I don't know if it helped you Siriraks, but it certainly helped me!

JJ