Chirostenotes has a confusing history of discovery and naming. The first fossils of
Chirostenotes, a pair of hands, were in 1914 found by
George Fryer Sternberg near
Little Sandhill Creek in the
Campanian Dinosaur Park Formation of Canada, which has yielded the most dinosaurs of any Canadian formation. The specimens were studied by
Lawrence Morris Lambe who, however, died before being able to formally name them. In 1924,
Charles Whitney Gilmore adopted the name he found in Lambe's notes and described and named the
type species Chirostenotes pergracilis. The generic name is derived from Greek
cheir, "hand", and
stenotes, "narrowness". The
specific name means "throughout",
per~, "gracile",
gracilis, in
Latin. The
holotype is
CMN 2367, the pair of hands. Gilmore tentatively referred another specimen, CMN 343, to
Chirostenotes pergracilis. CMN 343 is a set of jaws with strange teeth found several miles away from the holotype. Much later in the 1980s, it was known that
Chirostenotes was a toothless oviraptorosaur, and the jaws were designated the holotype specimen of
Richardoestesia gilmorei and are from an otherwise poorly known dinosaur, possibly a
dromaeosaurid.
Chirostenotes was but the first name assigned. Feet were then found, specimen CMN 8538 (also from the Dinosaur Park Formation), and in 1932
Charles Mortram Sternberg gave them the name
Macrophalangia canadensis, meaning 'large toes from Canada'. Sternberg correctly recognized them as part of a meat-eating dinosaur but thought they belonged to an
ornithomimid. In 1936, its lower jaws, specimen CMN 8776, were found by
Raymond Sternberg near
Steveville and in 1940 he gave them the name
Caenagnathus collinsi. The generic name means 'recent jaw' from Greek
kainos, "new", and
gnathos, "jaw"; the specific name honours
William Henry Collins. The toothless jaws were first thought to be those of a
bird. Slowly the precise relationship between the finds became clear. In 1960
Alexander Wetmore concluded that
Caenagnathus was not a bird but an ornithomimid. In 1969
Edwin Colbert and
Dale Russell suggested that
Chirostenotes and
Macrophalangia were one and the same animal. In 1976
Halszka Osmólska described
Caenagnathus as an oviraptorosaurian. In 1981 the announcement of
Elmisaurus, an Asian form of which both hand and feet had been preserved, showed the soundness of Colbert and Russell's conjecture. In 1988, a specimen from storage since 1923 was discovered and studied by
Philip J. Currie and Dale Russell. This fossil helped link the other discoveries into a single dinosaur. Since the first name applied to any of these remains was
Chirostenotes, this were the only name that was recognized as valid. Currie and Russell also addressed the complicating issue of a possible second form being present in the material. In 1933
William Arthur Parks had named
Ornithomimus elegans, based on specimen ROM 781, another foot from Alberta. In 1971,
Joël Cracraft, still under the assumption
Caenagnathus was a bird, had named a second species of
Caenagnathus:
Caenagnathus sternbergi, based on specimen CMN 2690, a small lower jaw. In 1988 Russell and Currie concluded that these fossils might present a more gracile
morph of
Chirostenotes pergracilis. In 1989 however, Currie thought that they represented a separate smaller species, and named this as a second species of the closely related
Elmisaurus:
Elmisaurus elegans. In 1997, this was renamed to
Chirostenotes elegans by
Hans-Dieter Sues. The species was moved to the new genus
Leptorhynchos in 2013. Several larger skeletons from the early
Maastrichtian Horseshoe Canyon Formation of Alberta and the late
Maastrichtian Hell Creek Formation of
Montana and
South Dakota have been referred to
Chirostenotes in the past, though more recent studies concluded that they represent several new species. The Horseshore Canyon formation specimen was renamed
Epichirostenotes in 2011, while the Hell Creek Formation specimens have been referred to the genus
Anzu. In 2007 a
cladistic study by
Philip Senter cast doubt on the idea that all of the large Dinosaur Park Formation fossils belonged to the same animal. Coding the original hand and jaw specimens separately showed that while the
Caenagnathus holotype remained in the more basal position in the
Caenagnathidae commonly assigned to it, the
Chirostenotes pergracilis holotype was placed as an advanced oviraptorosaurian and an
oviraptorid. Subsequent studies found that the
Caenagnathus jaws did in fact group together with other traditional caenagnathids, but not necessarily
Chirostenotes. ==Description==