Shapiro et al.'s new ornithomimosaur

["Nicholas Gardner" <ratites637@hotmail.com>]

Michael D. Shapiro, Hailu You, Neil H. Shubin, Zhexi Luo, & Jason Philip 
Downs (2003).  A LARGE ORNITHOMIMID PES FROM THE LOWER CRETACEOUS OF THE 
MAZONGSHAN AREA, NORTHERN GANSU PROVINCE, PEOPLE'S REPUBLIC OF CHINA. 
Journal of Vertebrae Paleontology 23(3):695-698

Shapiro et al. describe a possible new species of ornithomimosaur based on 
partial pedal material.

cf. Ornithomimidae
Material:  IVPP V12756, "a partial right foot" (astragalus, calcaneum, pedal 
digit II, pIII-1, pIII-2, pIV-3, pIV-4; pIV-5, mtt II, mtt III) & 
"fragmentary phalanges of a left foot" (pIII-1, pIII-2, pIV-1, pIV-5)
Horizon:  Xinminbiao Group of Mazongshan Area, Gansu Province, China 
(Aptian-Albian)

I ran this very fragmentary specimen in the data matrix from Kobayashi & Lü 
(2003).  It could, unfortunately, only be coded for one character (38).  The 
results from Heuristic search-

Strict consensus tree of 15 trees, 58 steps-

--+--Allosaurus
  |--Tyrannosaurids
  `--+--Pelecanimimus
     `--+--Harpymimus
        `--+--Garudimimus
           |--Archaeornithomimus
           |--Anserimimus
           |--Gallimimus
           |--Struthiomimus
           |--Dromiceiomimus
           |--Ornithomimus
           |--Sinornithomimus
           `--IVPP V12756

Unfortunately, in all 15 trees, IVPP V12756 tries out various positions with 
all ornithomimosaurs more derived than Harpymimus. This is due to its 
fragmentary nature (which as noted above meant it could only be coded with 
any certainty for one character).

Shapiro suggest that IVPP V12756 represents a basal ornithomimosaur, 
possibly more primitive than Harpymimus and Garudimimus, and is possibly 
related to the former, following Dr. Holtz's 2001 paper which evidentally 
suggests that H. reverses the pes to a non-arctometatarsalian state.  
However, referring to more recent papers from various authors (Holtz, the 
AMNH team, etc.), it is more likely that the arctometatarsus was 
independently developed among various groups within the Coelurosauria 
(tyrannosaurids, ornithomimids, caenagnathids, & troodontids).  Therefore, I 
suggest instead that IVPP V12756 is closer to more derived ornithomimosaurs 
and that it is possibly those more derived than Garudimimus.  Hopefully more 
material will be recovered in the future which should make the situation 
clearer.

Another interesting note is that IVPP V12756 represents the third largest 
(not the second largest as implied by Shapiro et al.), the second being 
actually Gallimimus, and the first being Deinocheirus, of course. ^_^

Nick Gardner

References-

Yoshitsugu Kobayashi & Jun-Chang Lü (2003).  A new ornithomimid dinosaur 
with gregarious habits from the Late Cretaceous of China.  Acta 
Palaeontologica Polonica 48(2):235-259

Michael D. Shapiro, Hailu You, Neil H. Shubin, Zhexi Luo, & Jason Philip 
Downs (2003).  A LARGE ORNITHOMIMID PES FROM THE LOWER CRETACEOUS OF THE 
MAZONGSHAN AREA, NORTHERN GANSU PROVINCE, PEOPLE'S REPUBLIC OF CHINA. 
Journal of Vertebrae Paleontology 23(3):695-698

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