Re: Confuciusornis and other feathered beasts

["Thomas R. Holtz, Jr." <th81@umail.umd.edu>]

At 08:51 AM 6/6/99 EDT, Barbara Saffer wrote:

>I note that "The Encyclopedia of Dinosaurs" refers to Confuciusornis as a 
>'toothless bird'.  In other places, I read that it is a feathered dinosaur (I 
>assume this means non-avian dinosaur).

Your assumption would not be entirely correct.  Unlike _Caudipteryx_ and
_Protarchaeopteryx_ (NOT _Protoarchae..._), _Caudipteryx_ is most definitely
a bird under everyone's definition.

>Could someone tell me if 
>Confuciusornis (as well as Caudipteryx and  Protoarchaeopteryx) are 
>considered  "non-avian feathered dinosaurs" by dinosaur paleontologists.

The crux here concerns the two primary different definitions of Aves used by
professional paleontologists.

Definition #1: Aves = all descendants of the most recent common ancestor of
ratites, tinamous, and neognaths.  In this definition, Aves = the modern
bird clade, and _Confuciusornis_, _Caudi._, and _Prot._ are all non-avian
feathered dinosaurs.  Under this definition, _Archaeopteryx_, _Hesperornis_,
and such are not avians either.  Instead, they are part of the more
inclusive group Avialae.

Definition #2: Aves = all descendants of the most recent common ancestor of
_Archaeopteryx_ and Neornithes (with Neornithes = Aves Definition #1 above).
In this scheme, _Confuciusornis_ is clearly within Aves, and thus an avian
feathered dinosaur.  However, if the phylogenies presented at the Ostrom
Symposium are correct, neither _Caudi._ nor _Prot._ are within Aves, and are
thus still non-avian feathered dinos.

Is this clear?  If not, I'll try and make things a little clearer.

>I'm 
>assuming Sinosauropteryx is unequivocally a non-avian dinosaur with some kind 
>of  feathers.  Right?

Yes.  (Okay, there's a few out there who think that the structures are
really a sea-snake fin...).

>Also, does anyone know if those "new" ankylosaurs from Utah have been named 
>yet?  The article I dug up on the Internet said they would be named for some 
>of the people on the dig -- but doesn't say what the names will be. 

Could you be a bit more precise WHICH new ankylosaurs?  _Mymoorapelta_ and
_Gastonia_ and _Gargoyleosaurus_ have all been named, and xxxxx still isn't
formally named yet.

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