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Re: Placement of Segnosauria (was Re: Details on Nanshiungosaurus bohlini)
T. Mike Keesey wrote:
I mention "indeterminate material (neck vertebra) -- late Late Jurassic --
U.S.A.". Looking back in the DML archives, I find this quote from Timothy
Williams: "There's also possible oviraptorosaur[s] from the mid-Cretaceous
of Australia and Brazil, and a caudal vertebra from the Morrison." I must
have made an error when I wrote "neck vertebra" -- will correct shortly.
Here's the info on the oviraptorosaur/segnosaur vertebrae from Wyoming and
South America (and apologies to Mike and everyone else if this contradicts
an earlier post of mine).
YPM 1996 and 1997: Two cervical vertebrae, probably fifth and fourth
respectively, previously referred to _Coelurus fragilis_.
Locality: Quarry 9, Como Bluff, Wyoming.
Horizon: Morrison Formation.
Mackovicky (1997) held off naming this small theropod, even though the
cervicals shows unique features which distinguish YPM 1996/1997 from other
small theropods. The cladogram of Frankfurt and Chiappe (1999), based on
cervical morphology, placed YPM 1996/1997 on the
therizinosaur/oviraptorosaur lineage, and basal to both Therizinosauridae
and Oviraptoridae. This paper also described a possible oviraptorosaur from
the Late Cretaceous of Argentina, based upon a single cervical vertebra:
MACN-622: Cervical vertebra (fourth or fifth).
Locality: Estancia El Brete, southern Salta Province, Argentina.
Horizon: Lecho Formation.
There's also putative oviraptorosaur material dotted around Gondwana,
including a partial sacrum from the Santana Formation described by Frey and
Martill (1995), and stuff from Dinosaur Cove (partial jaw, vertebra)in
Frankfurt, N.G. and Chiappe, L.M. (1999). A possible oviraptorosaur from
the Late Cretaceous of northwestern Argentina. J. Vert. Paleont. 19:
Mackovicky, P.J. (1997). A new small theropod from the Morrison Formation
of Como Bluff, Wyoming. J. Vert. Paleont. 17: 755-757.
And Tracy Ford wrote (in reply to my earlier post)...
(a) and (b) refer to the association of the _Beipiaosaurus_ type material.
There's nothing that suggests to me that the material is chimeric.
I disagree. The jaw is way to small to fit an animal with the body size
the skeleton suggests. The manus and claws is too dromaeosaurid for me.
Even allowing for the fact that segnosaurs/therizinosaurs have very small
heads? You could be right though.
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