Yanornis abstract translation

[bh480@scn.org]

From: Ben Creisler bh480@scn.org

Yanornis abstract translation

As promised, here are rough translations of the abstract
for the paper on Yanornis and Yixianornis and the caption
for the photo of the type specimen of Yanornis. I want to
thank Michael Turton again for providing basic
translations that allowed me to concentrate on more
technical terms--especially the Latin names for  taxa
mentioned in the Chinese form only.  Also many thanks to
various list members who sent me copies of the text and
instructions on making my browser decode the Chinese
characters. Any errors, though, are my own--since an
official English version of the abstract as well as of the
paper should appear in a few months, others may judge how
well I did.

My biggest goof in the initial posting was to guess that
Yanornis might be an enantiornithine--based on the photo
it was much more complete than any known ornithurine
specimens and had fairly large manual claws and long
toothed jaws. At the time, I could not get the browser on
my home computer to decipher the encoded Chinese
characters so I could read the caption or the abstract. I
eventually got the full Chinese text in readable form by
using computers at the University of Washington Library
that had the necessary Internet Explorer files, and I
posted a correction.

Yanornis is a major discovery since it is the first almost
complete skeleton of an ornithurine bird known from the
Early Cretaceous (probably Albian)--the recently described
Apsaravis apparently dates from the Campanian and was the
most complete ornithurine discovered since Ichthyornis and
Hesperornis in the 19th century.

I'll do a separate posting providing the Chinese names for
various Mesozoic birds and higher taxa.

http://www.scichina.com/kz/0105/kz0371.stm

Zhou Zhonghe and Zhang Fucheng, 2001. [Two new genera of
ornithurine birds from the Early Cretaceous of Liaoxi
related to the origin of modern birds.] Kexue Tongbao 46
(5): 371-377  (in Chinese)

Abstract (rough translation): This paper reports the
discovery in Liaoning Province of two new species of
Mesozoic ornithurine fossil birds: Yanornis martini gen.
nov. et sp. nov and Yixianornis grabaui gen. nov. et sp.
nov. They represent the most complete ornithurines birds
known so far from the Early Cretaceous fossil record.
These two types of birds are more advanced than Liaoning
ornithurines, but closer to Chaoyangia and Songlingornis.
Compared with other Cretaceous birds such as Confuciornis,
Liaoxiornis and Eoenantiornis, the two new birds
have distinctly advanced features resembling those of
modern birds, and had strong flying ability.  Yanornis has
a larger body and longer skull than Yixianornis and
Chaoyangia,with comparatively long forelimbs. The
discovery of these new ornithurine fossils makes clear
that during the Early Cretaceous, regardless of the
comparatively distant relationship of modern birds with
the Enantiornithes, the radiation and diversification of
ornithurine birds included the common ancestor of modern
birds. The flight structures of Yanornis and Yixianornis
are advanced compared with Archaeopteryx, Confuciusornis
and the Enantiornithes, and have no clear distinction from
those of modern birds. While there is no obvious
difference in those structures, other structures of these
two birds still retain some primitive features such as
teeth in the upper and lower jaws, well developed manual
claws, and pubic bones joined at the distal end.  Such
details make it clear that the most recent ancestor of
modern birds probably appeared at a later time period.

Key terms: Ornithurae origin radiation  Jiufotang
Formation Yanornis Yixianornis

Photograph of Yanornis
http://www.scichina.com/kz/0105/kzfm05.stm

Two important branches of birds existed in the Mesozoic.
One was the diverse and numerous Enantiornithes that went
extinct at the end of the Cretaceous; the other branch was
the Ornithurae. During the Early Cretaceous ornithurines
were less numerous, and previously a complete specimen had
not been found. However, Yanornis, most closely related to
modern birds, is one of the two almost completely
preserved Early Cretaceous fossil birds from Liaoxi.  It
is different from Archaeopteryx, Confuciornis, and other
primitive birds, and belongs in the Ornithurae. There are
no obvious differences between the flight structures of
Yanornis and modern birds.  Despite this, it preserves a
number of primitive features; for example, its upper and
lower jaws have teeth, it has well developed manual claws,
and so on.  These details indicate that the most recent
common ancestor of modern birds appeared at a later time
period. Research into Early Cretaceous ornithurines not
only enables us to broaden our understanding of the
radiation of Mesozoic birds, but is also supremely
important for our understanding of the origins of modern
birds.