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Re: Senter et al. 2004 impressions



T. Michael Keesey wrote:


Since _Deinocheirus_ has long been thought to be an ornithomimosaur,

Not by everyone. With only a pair of forelimbs to go by, it's proven difficult to nail the affinities of our good friend _Deinocheirus_. And I wonder if the features used to link _Deinocheirus_ and ornithomimosaurs might be symplesiomorphous.


it was supposed to have an arctometatarsalian pes (or reversal from that state, as you
say)

On second consideration, if _Deinocheirus_ is sister taxon to an Alvarezsauridae+Ornithomimosauria clade (as Senter's thesis says), then the arctomet pes may not be primitive for _Deinocheirus_- since basal alvarezsaurids apparently do not display this condition. (Not sure about basal ornithomimosaurs; an undescribed taxon from Asia may shed some light on this.)


Thus, the arctomet pes could have evolved independently in each of the groups Alvarezsauridae, Ornithomimosauria and Troodontidae, as well as in _Avimimius_ and/or Caenagnathidae (=Elmisauridae), and (of course) Tyrannosauridae.



Tim

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