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Re: Deinocheirus?



>     My references are cryptic concerning the deinocheirus. Could
>someone tell me during which period it lived, and how it's possible
>to determine that it is a member of the ornithomimid family, given the
>fragmentary nature of the fossils that have been found? Thanks!

Deinocheirus mirificus is from the Nemegt Formation of Mongolia, which
makes it of probable early Maastrichtian age (in the Late Cretaceous, older
than the Lancian faunas of North America [Tyrannosaurs, Triceratops,
Ankylosaurus, Anatotitan, etc.] but younger than the Judithian faunas of
North America [Gorgosaurus, Centrosaurus, Euoplocephalus, Maiasaura,
etc.]).

The proportions of the metacarpals and digits are the same as in an
advanced ornithomimosaur.  Its claws are not terribly curved nor are they
blade-like (despite some illustrations to the contrary).  The humerus,
radius, and ulna are all of ornithomimid shape (fairly slender,
deltapectoral crest fairly subdued, etc.).  Every thing in the skeleton
screams "ornithomimosaur", and there is no evidence to the contrary.  Even
its size doesn't place it outside of the Ornithomimidae, since large
individuals of Gallimimus reaches about half the expected size.

                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.