Chirostenotes

{{Short description|Extinct genus of dinosaurs}}

{{Automatic taxobox

| fossil_range = Late Cretaceous, {{Fossil range|76.5|75}}

| image = Chirostenotes skeletal.jpg

| image_caption = Skeletal diagram showing known elements of C. pergracilis

| taxon = Chirostenotes

| authority = Gilmore, 1924

| type_species = Chirostenotes pergracilis

| type_species_authority = Gilmore, 1924

| synonyms =

• Macrophalangia canadensis Sternberg, 1932
• Caenagnathus sternbergi? Cracraft, 1971

}}

Chirostenotes ({{IPAc-en|ˌ|k|aɪ|r|oʊ|s|t|ᵻ|ˈ|n|oʊ|t|iː|z}} {{respell|KY|roh|stin|OH|teez}}; named from Greek 'narrow-handed') is a genus of oviraptorosaurian dinosaur from the late Cretaceous (about 76.5–75 million years ago{{cite journal|last1=Gardner|first1=James D.|last2=Henderson|first2=Donald M.|last3=Therrien|first3=François|title=Introduction to the Special Issue commemorating the 30th anniversary of the Royal Tyrrell Museum of Palaeontology, with a summary of the museum's early history and its research contributions|journal=Canadian Journal of Earth Sciences|year=2015|volume=52|issue=8|page=7|doi=10.1139/cjes-2015-0059|bibcode=2015CaJES..52D...5G|doi-access=free}}) of Alberta, Canada. The type species is Chirostenotes pergracilis.

==History of discovery==

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.{{cite journal | last1 = Gilmore | first1 = C.W. | year = 1924 | title = A new coelurid dinosaur from the Belly River Cretaceous of Alberta | journal = Canada Department of Mines Geological Survey Bulletin (Geological Series) | volume = 38 | issue = 43| pages = 1–12 }}

{{Multiple image

| image1 = Chirostenotes pergracilis hand.jpg

| image2 = Chirostenotes pergraclis.jpg

| total_width = 400

| footer =

| align = center

| caption1 = Right hand (A & B), left hand (C & D). Reconstruction of a right hand based on a composite of both hands (E).

| header = Holotype (CMN 2367)

| caption2 = Illustration of the left hand from the 1924 description.

}}

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.Currie, P.J., Rigby, Jr., J.K., and Sloan, R.E. (1990). Theropod teeth from the Judith River Formation of southern Alberta, Canada. In: Carpenter, K., and Currie, P.J. (eds.). Dinosaur Systematics: Perspectives and Approaches. Cambridge University Press:Cambridge, 107-125. {{ISBN|0-521-36672-0}}.

File:Chirostenotes limbs.jpg

Chirostenotes was but the first name assigned. Feet were then found, specimen CMN 8538 (also from the Dinosaur Park Formation),{{Cite journal |last=Funston |first=Gregory |date=2020-07-27 |title=Caenagnathids of the Dinosaur Park Formation (Campanian) of Alberta, Canada: anatomy, osteohistology, taxonomy, and evolution |url=https://journals.library.ualberta.ca/vamp/index.php/VAMP/article/view/29362 |journal=Vertebrate Anatomy Morphology Palaeontology |language=en |volume=8 |pages=105–153 |doi=10.18435/vamp29362 |issn=2292-1389|hdl=20.500.11820/f6c20f71-bad4-4d1c-b1b3-efcddca9c558 |hdl-access=free }} and in 1932 Charles Mortram Sternberg gave them the name Macrophalangia canadensis, meaning 'large toes from Canada'.{{cite journal | last1 = Sternberg | first1 = C.M. | year = 1932 | title = Two new theropod dinosaurs from the Belly River Formation of Alberta | journal = Canadian Field-Naturalist | volume = 46 | issue = 5| pages = 99–105 }} 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.{{cite journal | last1 = Sternberg | first1 = R.M. | year = 1940 | title = A toothless bird from the Cretaceous of Alberta | journal = Journal of Paleontology | volume = 14 | issue = 1| pages = 81–85 }}

Slowly the precise relationship between the finds became clear. In 1960 Alexander Wetmore concluded that Caenagnathus was not a bird but an ornithomimid.Wetmore, A. 1960. A classification for the birds of the world. Smithsonian Miscellaneous Collections 139 (11): 1–37 In 1969 Edwin Colbert and Dale Russell suggested that Chirostenotes and Macrophalangia were one and the same animal.E.H. Colbert and D.A. Russell, 1969, "The small Cretaceous dinosaur Dromaeosaurus", Amer. Mus. Novit., No. 2380, pp. 1-49 In 1976 Halszka Osmólska described Caenagnathus as an oviraptorosaurian.{{cite journal | last1 = Osmólska | first1 = H. | year = 1976 | title = New light on the skull anatomy and systematic position of Oviraptor | journal = Nature | volume = 262 | issue = 5570| pages = 683–684 | doi=10.1038/262683a0| bibcode = 1976Natur.262..683O | s2cid = 4180155 }} 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.

{{Multiple image

| image1 = Pelvic elements of Chirostenotes.jpg

| image2 = Chirostenotes RTMP 79.20.1.jpg

| total_width = 240

| footer = Assigned specimen TMP 1979.020.0001, from the Dinosaur Park Formation.

| direction = vertical

}}

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.{{cite journal | last1 = Currie | first1 = P.J. | last2 = Russell | first2 = D.A. | year = 1988 | title = Osteology and relationships of Chirostenotes pergracilis (Saurischia, Theropoda) from the Judith River (Oldman) Formation of Alberta, Canada | doi = 10.1139/e88-097 | journal = Canadian Journal of Earth Sciences | volume = 25 | issue = 7| pages = 972–986 | bibcode = 1988CaJES..25..972C }}

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.{{cite journal | last1 = Parks | first1 = W.A. | year = 1933 | title = New species of dinosaurs and turtles from the Upper Cretaceous formations of Alberta | journal = University of Toronto Studies, Geological Series | volume = 34 | pages = 1–33 }} 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.{{cite journal | last1 = Currie | first1 = P.J. | year = 1989 | title = The first records of Elmisaurus (Saurischia, Theropoda) from North America | journal = Canadian Journal of Earth Sciences | volume = 26 | issue = 6| pages = 1319–1324 | doi=10.1139/e89-111| bibcode = 1989CaJES..26.1319C }} In 1997, this was renamed to Chirostenotes elegans by Hans-Dieter Sues.{{cite journal | last1 = Sues | first1 = H.D. | year = 1997 | title = On Chirostenotes, a Late Cretaceous oviraptorosaur (Dinosauria: Theropoda) from Western North America | journal = Journal of Vertebrate Paleontology | volume = 17 | issue = 4| pages = 698–716 | doi=10.1080/02724634.1997.10011018}} The species was moved to the new genus Leptorhynchos in 2013.{{Cite journal | last1 = Longrich | first1 = N. R. | last2 = Barnes | first2 = K. | last3 = Clark | first3 = S. | last4 = Millar | first4 = L. | title = Caenagnathidae from the Upper Campanian Aguja Formation of West Texas, and a Revision of the Caenagnathinae | doi = 10.3374/014.054.0102 | journal = Bulletin of the Peabody Museum of Natural History | volume = 54 | pages = 23–49 | year = 2013 | s2cid = 128444961 }}

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.{{cite journal |author=Robert M. Sullivan, Steven E. Jasinski and Mark P.A. Van Tomme |year=2011 |title=A new caenagnathid Ojoraptorsaurus boerei, n. gen., n. sp. (Dinosauria, Oviraptorosauria), from the Upper Ojo Alamo Formation (Naashoibito Member), San Juan Basin, New Mexico |url=http://www.robertmsullivanphd.com/uploads/169._Sullivan_et_al.__Ojoraptorsaurus__COLOR.pdf |journal=Fossil Record 3. New Mexico Museum of Natural History and Science Bulletin |volume=53 |pages=418–428}} The Horseshore Canyon formation specimen was renamed Epichirostenotes in 2011, while the Hell Creek Formation specimens have been referred to the genus Anzu.{{Cite journal | doi = 10.1371/journal.pone.0092022| title = A New Large-Bodied Oviraptorosaurian Theropod Dinosaur from the Latest Cretaceous of Western North America| journal = PLOS ONE| volume = 9| issue = 3| pages = e92022| year = 2014| last1 = Lamanna | first1 = M. C. | last2 = Sues | first2 = H. D. | last3 = Schachner | first3 = E. R. | last4 = Lyson | first4 = T. R. | pmid=24647078 | pmc=3960162| bibcode = 2014PLoSO...992022L| doi-access = free}}

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.{{cite journal | last1 = Senter | first1 = P | year = 2007 | title = A new look at the phylogeny of Coelurosauria (Dinosauria: Theropoda) | journal = Journal of Systematic Palaeontology | volume = 5 | issue = 4| pages = 429–463 | doi=10.1017/s1477201907002143| s2cid = 83726237 }} Subsequent studies found that the Caenagnathus jaws did in fact group together with other traditional caenagnathids, but not necessarily Chirostenotes. New specimens described by Funston et al. (2015) and Funston & Currie (2020) indicated that Chirostenotes is a distinct form from Caenagnathus.{{Cite journal | doi = 10.1016/j.cretres.2014.12.002| title = New material of the large-bodied caenagnathid Caenagnathus collinsi from the Dinosaur Park Formation of Alberta, Canada| journal = Cretaceous Research| volume = 54| pages = 179–187| year = 2015| last1 = Funston | first1 = G. F. | last2 = Persons | first2 = W. S. | last3 = Bradley | first3 = G. J. | last4 = Currie | first4 = P. J. }}{{Cite journal |last=Funston |first=G. F. |last2=Currie |first2=P. J. |date=2021-09-02 |title=New material of Chirostenotes pergracilis (Theropoda, Oviraptorosauria) from the Campanian Dinosaur Park Formation of Alberta, Canada |journal=Historical Biology |language=en |volume=33 |issue=9 |pages=1671–1685 |doi=10.1080/08912963.2020.1726908 |issn=0891-2963|hdl=20.500.11820/990cb4be-8a56-4248-ac47-e4fddad8f7ba |hdl-access=free }}