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Mesozoic Birds -- NEW STUFF!!!



>  I wasn't aware that Protoavis had been accepted as a true
> bird. Last I heard of the specimen was a section in "Kings
> of Creation",and opinions on the material were a bit
> diverse. Some paleontologists even remarked that they were
> doubtful that all of the material belonged to the same
> animal.

        Well, this is timely, as it serves as a launching pad for some new
information.  To answer the question first, though:  some people regard
_Protoavis_ as a definite bird, others do not.  Rumor mill says Chatterjee
has backed off of some of his claims, but apparently some find it more
parsimonious to believe _Protoavis_ a bird.

        And now for the new stuff...

        One of my advisors, Dale Winkler, back from the Sixth Symposium on
Mesozoic  Terrestrial Ecosystems in Beijing, allowed me to peruse the
volume of short papers for the symposium.  There are a number of entries
concerning Mesozoic birds, which makes perfect sense as many of the newest
finds (which are apparently rewriting avian history) are from China and
elsewhere in Asia.  Many were on display.  I have xeroxed the papers, and I
have not yet read them, so everything here is just brief overviews for the
collective benefit.

        Anyway, the most noteworthy new entry is a Late Jurassic bird from
China (this is _not_, to my knowledge, the Korean bird!!!) which has been
named _Confuciusornis_.  (This bird and name have been rumored for about 3
years now, but this is the first I've seen in print.)  The paper compares
this bird, represented by a fairly complete and well-preserved skeleton
including skull and feather impressions, to _Archaeopteryx_, with which the
author (Lianhai Hou) places it in the Sauriurae.  The skull is much more
birdy than that of _Archaeopteryx_, including complete toothlessness and a
shorter rostrum...er, snout.  ;-)  (There are reportedly tooth impressions
in the premaxilla, but not in the maxilla.)

        The forelimb retains three separate digits with large claws.  The
humerus is peculiar with a hatchet shape and a large pneumatic foramen in
the proximal end -- it's really funky looking!  The pelvis is also much
more bird-like than that of _Archaeopteryx_ (as drawn--no photos are
included, unfortunately), with a longer, lower ilium, a bootless,
retroverted pubis, and a stubby ilium (which retains the odd prong of
_Archaeopteryx_).  The hind leg is made up of a femur and an apparently
true tibiotarsus (no mention of the status of the fibula), including,
oddly, a patella.  The foot is similar to _Archaeopteryx_.  The fossil
apparently has feather impressions on both sides of the tibiotarsus, thus
indicating that at least this bird has feathered legs.

        Another paper, by Larry Martin and Desui Miao, compares the origin
and evolutionary rates of Mesozoic birds to contemporaneous mammals.  This
paper is important because it confirms a rumor I've been hearing for some
time now, that most Mesozoic bird workers are now leaning towards this
interpretation of the Mesozoic bird record:  Most of the new Early
Cretaceous birds (including _Sinornis_, _Cathayornis_, _Iberomesornis_,
_Concornis_, and _Noguerornis_), and several of the Late Cretaceous ones,
are enantiornithurine birds.  Some, like Martin, even want to include
_Archaeopteryx_ as an enantiornithurine.  The first "modern" birds are
_Gansus_, _Ambiortus_, and possibly _Gallornis_.  The enantiornithurines,
BTW, would also fall into the Sauriurae, while the more modern forms are in
the Ornithurae.  The previous position of the enantiornithurines has been
contentious.  Martin also states that _Protoavis_ is currently of
indeterminate status.

        A subsequent paper, by Eugen Kessler and Erika Gall (Romania),
declares that that the fossil evidence of birds points clearly to a Lower
or Middle Triassic thecodontian ancestor, and declares _Protoavis_ to be a
definite bird.  George, you'll like this paper!  ;-)

        Another paper by Evgeny Kurochkin, a noted Russian bird worker, is
important in that it references a number of Mesozoic birds of which I was
unaware, apparently having been published in restricted-distribution
Russian journals.  A large number of these, from the Early and Late
Cretaceous, are enantiornithurines (e.g. _Zhyraornis_).  He also puts
_Gobipteryx_ as an enantiornithurine.  Other apparently "true" birds are
referenced, like _Horezmavis_ and _Platanavis_.  He also likens the new
Early Cretaceous _Chaoyangia_ to the later Patagonian bird _Patagopteryx_.


        Consensus seems to be that of all the Mesozoic birds,
enantiornithurines are the most common and diverse.  Thus, we also have to
state that the enantiornithurines are an entire group of birds that went
extinct at the K/T boundary, while modern birds continued on -- this is
something Feduccia stated recently in an article in _Nature_.  I am
presuming that a great deal of this seemingly sudden shift of perspective
will be covered in the forthcoming book on Mesozoic birds (Dr. Witmer,
would you care to comment?).

        As I said before, this is all just a brief overview stemming from
my having skimmed these papers.  I intend to read them more closely soon.
Oh, and before I go:  if anyone wants to order a copy of this book, I do
not know how as yet, but it is published by:

        China Ocean Press
        No.1 Fuxingwenmai Street
        Beijing  China
        100860

and the ISBN is 7-5027-3898-3/Q.116.



Jerry D. Harris
Schuler Museum of Paleontology
Southern Methodist University
jdharris@lust.isem.smu.edu
        (Compuserve:  73132,3372)

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TITLE OF A REAL SCIENTIFIC PAPER:

"South American Animals and Their Lice"

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