Struthiomimus
Name:
Struthiomimus
(Ostrich mimic).
Phonetic: Stru-fee-oh-mime-us.
Named By: Henry Fairfield Osborn - 1917.
Synonyms: Ornithomimus altus,
Ornithomimus sedens.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Theropoda, Ornithomimidae.
Species: S. altus (type),
S.
sedens.
Diet: Uncertain but possibly an omnivore.
Size: 4.3 meters long, 1.4 meters high at the
hip.
Known locations: Canada, Alberta - Dinosaur
Park Formation and Horseshoe Canyon Formation. USA - Hell Creek
Formation.
Time period: Late Campanian/Early Maastrichtian of
the Cretaceous.
Fossil representation: Many individuals.
Struthiomimus
remains were actually known all the way back to 1901, but were
interpreted by Lawrence Lambe to belong to Ornithomimus
altus, the
first ornithomimid
to be named. In 1917 however, Henry
Fairfield Osborn (the man who is perhaps best remembered for naming
Tyrannosaurus)
identified key differences in the bones, especially
the hands and renamed the remains as a new genus, Struthiomimus.
Despite the difference, Struthiomimus and Ornithomimus
are still
very much like one another, and between them they seem to have been
the two most common types of ornithomimid active in North America.
The
signature feature of Struthiomimus is the hand size
in that the hands
are proportionately longer in relation to the rest of the arm than in
other known ornithomimid genera. With this feature in mind, it’s
possible that Struthiomimus may have had a greater
reliance upon using
its hands for feeding, although like with other ornithomimids this,
what Struthiomimus ate remains a mystery to be
certain.
Like
with its close relatives, Struthiomimus had a
keratinous toothless
beak in life, which could have been used for a variety of different
feeding strategies. Osborn speculated that Struthiomimus
was a
selective browser that used this narrow beak to pick out the most
nutritious parts of plants. The hands could also have been used to
reach around branches and pull down more of the plant to be within
range of the mouth. Other palaeontologists however have speculated
that Struthiomimus may have been more
insectivorous, using the beak
to pick out large grubs and insects, while others have gone even
further by suggesting that small reptiles like snakes and lizards as
well as small primitive mammals may have also been tackled. Today
however most prefer to think of Struthiomimus as an
omnivore which
could adapt to whatever food was available.
Omnivory
however is the most likely dietary preference for a relatively small
dinosaur like Struthiomimus. The strictly
herbivore niche would have
been filled by large numbers of ceratopsian
dinosaurs like Chasmosaurus
as well as other dinosaur types like ankylosaurs
such as Euoplocephalus
and hadrosaurs
like Edmontonsaurus. The predatory
niche would have
also been filled by large tyrannosaurs
such as Albertosaurus
as well as
smaller dromaeosaurs
like Dromaeosaurus.
But by moving between these
groups and adapting to different conditions, Struthiomimus
would be
able to coexist with these other forms, perhaps going some way to
explain the large number of ornithomimid remains in general.
The
classification of Struthiomimus is a little muddled
with many of the
named species that were named throughout the twentieth century being
reassigned to other ornithomimid genera. The 2010 renaming of
Ornithomimus edmontonicus to Struthiomimus
edmontonicus by Gregory S.
Paul has so far not found wide acceptance amongst palaeontologists
and as such edmontonicus usually remains
attributed to Ornithomimus.
Further reading
- Skeletal adaptations of Ornitholestes, Struthiomimus, Tyrannosaurus.
- Bulletin of the American Museum of Natural History 35(43):733-771 -
H. F. Osborn - 1916.
- Struthiomimus brevetertius - A new species of dinosaur from the
Edmonton Formation of Alberta. - Transactions of the Royal Society of
Canada, series 3. 20(4): 65-70. - W. A. Parks - 1926.
- Struthiomimus samueli, a new species of Ornithomimidae from the Belly
River Formation of Alberta. - University of Toronto Studies, Geology
Series 26:1-24. - W. A. Parks - 1928.
- A new specimen of Struthiomimus altus from Alberta, with comments on
the classificatory characters of Upper Cretaceous ornithomimids. -
Canadian Journal of Earth Sciences 18:518-526. - E. L. Nicholls
& A. R. Russel - 1981.
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