Chirostenotes
Name:
Chirostenotes
(Narrow handed).
Phonetic: Ky-ore-sten-o-teez.
Named By: Charles Whitney Gilmore - 1924.
Synonyms: Caenagnathus collinsi,
Caenagnathus sternbergi, Chirostenotes sternbergi, Elmisaurus
elegans, Ornithomimus elegans, Macrophalangia canadensis.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Oviraptoridea.
Species: C. pergracilis
(type).
Diet: Omnivore?
Size: 2 meters long.
Known locations: Canada - Alberta - Dinosaur
Park Formation.
Time period: Campanian of the Cretaceous.
Fossil representation: Partial remains.
Dinosaurs
and other extinct prehistoric animals often have complicated histories
regarding classification and Chirostenotes is no
exception to this.
First only the hands were found by George Fryer Sternberg in 1914.
First to study them were Lawrence Morris Lambe who unfortunately died
before he had chance to finish the description of them. Charles
Whitney Gilmore later named the hands Chirostenotes
in 1924 after
referring to Lambe’s notes.
Nothing
else happened until Charles Mortram Sternberg described fossilised feet
as Macrophalangia canadensis in 1932, a
reference to the large toes
that he thought were of an ornithomimid
dinosaur. In 1940 Raymond
Sternberg described a toothless jaw that he had found in 1936 as
Caenagnathus, but here the description was of what
was believed to be
a bird. In 1960 Alexander Wetmore would come closer to the mark
when he suggested that the jaw was that of an ornithomimid.
In
the closing decades of the twentieth century the full picture would
finally be pieced together, and to start in 1969 Edwin Colbert
and Dale Russell came up with the theory that the hands of
Chirostenotes and the feet of Macrophalangia
were of the same animal.
In 1976 the Polish palaeontologist Halszka Osmolska suggested that
Chirostenotes was an oviraptorid dinosaur, but
confirmation would not
come until 1981 when Osmolska described the oviraptorid
Elmisaurus
which also included both hands and feet. This confirmed the ideas
about Chirostenotes that had been proposed by
Osmolska, Colbert and
Russel. A further specimen studied in 1988 by Russel and Philip
Currie which had been in storage for around sixty-five years was the
final proof that Macrophalangia was indeed a
synonym to Chirostenotes.
As
for Caenagnathus, Russel and Currie examined
another jaw that had
been assigned to the genus as a second species by Joel Cracraft in
1971 and found that it may have been a more gracile (lightweight)
version of the Chirostenotes type species C.
pergracilis. However
in 1989 Currie assigned it and another fossil foot that had been
attributed as a species of Ornithiomimus
as O. elegans by William
Arthur Parks in 1933, to the Elmisaurus genus
as E. elegans.
This carried until 1997 when Hans-Dieter Sues reassigned it as a
species of Chirostenotes, and though this
action has been
questioned, most palaeontologists tend to agree with it due to the
wide geographical separation between the two specimens. Despite this
the precedent does exist for widely distributed fossils to belong to
the same genus but different species, such as with the hadrosaur
Saurolophus.
Fossils
of other large oviraptorids from the Horseshoe Canyon Formation and the
Hell Creek Formation have been considered to belong to Chirostenotes,
but later study has now raised the question of if they really belong,
and at least one new genus, Epichirostenotes
has already been
established from these individuals. The establishment of
Chirostenotes as an oviraptorid dinosaur has also
meant that some
theropod fossils, namely jaws and teeth have also had to be removed
from the genus. These were used to create the genus Richardoestesia
which might actually be a dromaeosaurid or troodontid theropod,
though most researchers side with the former.
Further reading
- A new coelurid dinosaur from the Belly River Cretaceous of Alberta. -
Canada Department of Mines Geological Survey Bulletin (Geological
Series) 38(43):1-12. - C. W. Gilmore - 1924.
- Osteology and relationships of Chirostenotes pergracilis
(Saurischia,
Theropoda) from the Judith River (Oldman) Formation of Alberta, Canada.
- Canadian Journal of Earth Sciences 25:972-986. - P. J. Currie
& D. A. Russel - 1988.
- On Chirostenotes, a Late Cretaceous
oviraptorosaur (Dinosauria:
Theropoda) from Western North America. - Journal of Vertebrate
Paleontology 17(4): 698-716. - H. D. Sues - 1997.
- Functional analysis of the hands of the theropod dinosaur
Chirostenotes pergracilis: evidence for an unusual
paleoecological
role. - PaleoBios 25: 9–19. - P. Senter & J. M. Parrish - 2005.
- A previously undescribed caenagnathid mandible from the late
Campanian of Alberta, and insights into the diet of Chirostenotes
pergracilis (Dinosauria: Oviraptorosauria). - Canadian Journal of Earth
Sciences. 51 (2): 156–165. - Gregory F. Funston & Philip J.
Currie - 2014.
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