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Re: _Liaoningornis_

At 09:17 PM 2/22/97 -0700, you wrote:
>Forgive me for bothering you, but do you know if _Liaoningornis_ the
>name of the feathered fossil found in Northeastern China?  Was it found
>in 1997 or late 1996?  Was it sparrow sized?  And was it likely a
>dinosaur or a prehistoric bird?  

There are a WHOLE mess of feathered forms from NE China: Liaoningornis is a
good old-fashioned bird, with a big sternum.

And, of course, birds ARE dinosaurs, so yes, it is a dinosaur AND a
prehistoric bird.

>And (on another train of thought) how would you tell the dif between a
>prehistoric bird and a small bird-like dinosaur? 

Well, to rephrase the question: How would you tell the dif between a
prehistoric bird and another sort of small dinosaur?

Above the level of Archaeopteryx, it becomes easy: a big keeled sternum, the
presence of a pygostyle (the shortened fused tail of birds), loss of a bunch
of dorsal vertebrae to the sacrum, and related features.

Archaeopteryx, however, is so phenomenally primitive, it is difficult to
distinguish it from non-avian forms.  Only a few features (not found in
dromaeosaurids) unite it with later birds.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661

"To trace that life in its manifold changes through past ages to the present
is a ... difficult task, but one from which modern science does not shrink.
In this wide field, every earnest effort will meet with some degree of
success; every year will add new and important facts; and every generation
will bring to light some law, in accordance with which ancient life has been
changed into life as we see it around us to-day."
        --O.C. Marsh, Vice Presidential Address, AAAS, August 30, 1877