Re: New Triassic Theropod Dinosaur - Tawa Hallae

[William_Parker@nps.gov]

Actually all three definitions are stem-based (branch based):

Theropoda - Birds and all saurischians that are closer to birds than they
are to
Sauropodomorphs, Gauthier (1986)

Ornithischia - Dinosaurs closer to Triceratops than to birds, Padian & May
(1993)

Saurischia - Birds and all dinosaurs that are closer to birds than they are
to Ornithischia,
Gauthier (1986)

>From Langer et al (2009)


************************************************************************
Bill Parker
Vertebrate Paleontologist
Division of Resource Management
Petrified Forest National Park
P.O. Box 2217
1 Park Road
Petrified Forest, AZ 86028
(928) 524-6228 x262


                                                                           
             Leo W Sham                                                    
             <leowsham@graduat                                             
             e.hku.hk>                                                  To 
                                       VRTPALEO@usc.edu,                   
             12/11/2009 12:21          William_Parker@nps.gov              
             AM                                                         cc 
                                       dinosaur@usc.edu, vrtpaleo@usc.edu  
                                                                   Subject 
                                       Re: New Triassic Theropod Dinosaur  
                                       - Tawa Hallae                       
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




Thanks for the very interesting news, but how come (on the web-blog
cladogram) Ornithischia,
Sauropodomorpha and Theropoda become "branch-based", not node-based as they
should be??

Quoting William_Parker@nps.gov:


 Sorry for the cross-posting.

 Today's issue of Science has an article on a new basal theropod, Tawa
 hallae,  from the Upper Triassic Chinle Formation of New Mexico by
Sterling
 Nesbitt, Nathan Smith, Randall Irmis, Alan Turner, Alex Downs, and Mark
 Norell.  Known from two almost complete specimens this new taxon clears up
 issues regarding the phylogeny and distribution of early theropods,
 including the phylogenetic position of herrerasaurs and Eoraptor.

 I've posted on this new find here:


http://chinleana.blogspot.com/2009/12/new-late-triassic-theropod-tawa-hallae.html



 ************************************************************************
 Bill Parker
 Vertebrate Paleontologist
 Division of Resource Management
 Petrified Forest National Park
 P.O. Box 2217
 1 Park Road
 Petrified Forest, AZ 86028
 (928) 524-6228 x262



~~~~~ LEO W SHAM  :)  MEDIC ET COMMISSIONED PALEO-ILLUSTRATOR ~~~~~