Chirostenotes: Difference between revisions

''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 (zoology)|specific name]] means "throughout", ''per~'', "gracile", ''gracilis'', in [[Latin]]. The [[holotype]] is '''NMC 2367''', the pair of hands.<ref name=CWG24>{{cite journal | last1 = Gilmore | first1 = C.W. | year = 1924 | title = A new coelurid dinosaur from the Belly River Cretaceous of Alberta | url = | journal = Canada Department of Mines Geological Survey Bulletin (Geological Series) | volume = 38 | issue = 43| pages = 1–12 }}</ref> Another fossil connected to ''Chirostenotes'' is specimen CMN&nbsp;8776, a set of jaws with strange teeth, which were originally referred by Gilmore to ''Chirostenotes pergracilis''. Now that it is known that ''Chirostenotes'' was a toothless oviraptorosaur, the jaws have been renamed ''[[Richardoestesia]]'' and are from an otherwise unknown dinosaur, likely a [[dromaeosaurid]].<ref name=CRR90>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}}.</ref>

''Chirostenotes'' was but the first name assigned. Feet were then found, specimen CMN&nbsp;8538, and in 1932 [[Charles Mortram Sternberg]] gave them the name ''Macrophalangia canadensis'', meaning 'large toes from Canada'.<ref name=CMS32>{{cite journal | last1 = Sternberg | first1 = C.M. | year = 1932 | title = Two new theropod dinosaurs from the Belly River Formation of Alberta | url = | journal = Canadian Field-Naturalist | volume = 46 | issue = 5| pages = 99–105 }}</ref> 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&nbsp;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]].<ref name=RMS36>{{cite journal | last1 = Sternberg | first1 = R.M. | year = 1940 | title = A toothless bird from the Cretaceous of Alberta | url = | journal = Journal of Paleontology | volume = 14 | issue = 1| pages = 81–85 }}</ref>

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

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&nbsp;781, another foot from Alberta.<ref name=WAP33>{{cite journal | last1 = Parks | first1 = W.A. | year = 1933 | title = New species of dinosaurs and turtles from the Upper Cretaceous formations of Alberta | url = | journal = University of Toronto Studies, Geological Series | volume = 34 | issue = | pages = 1–33 }}</ref> 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&nbsp;2690, a small lower jaw. In 1988 Russell and Currie concluded that these fossils might present a more gracile [[Polymorphism (biology)|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''.<ref name=PJC89>{{cite journal | last1 = Currie | first1 = P.J. | year = 1989 | title = The first records of ''Elmisaurus'' (Saurischia, Theropoda) from North America | url = | journal = Canadian Journal of Earth Sciences | volume = 26 | issue = 6| pages = 1319–1324 | doi=10.1139/e89-111}}</ref> In 1997, this was renamed to ''Chirostenotes elegans'' by [[Hans-Dieter Sues]].<ref>{{cite journal | last1 = Sues | first1 = H.D. | year = 1997 | title = On ''Chirostenotes'', a Late Cretaceous oviraptorosaur (Dinosauria: Theropoda) from Western North America | url = | journal = Journal of Vertebrate Paleontology | volume = 17 | issue = 4| pages = 698–716 | doi=10.1080/02724634.1997.10011018}}</ref> The species was moved to the new genus ''[[Leptorhynchos (dinosaur)|Leptorhynchos]]'' in 2013.<ref name=Caenagnathidae>{{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 | pmid = | pmc = }}</ref>

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 creature. 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 [[Oviraptoridae|oviraptorid]].<ref>{{cite journal | last1 = Senter | first1 = P | year = 2007 | title = A new look at the phylogeny of Coelurosauria (Dinosauria: Theropoda) | url = | journal = Journal of Systematic Palaeontology | volume = 5 | issue = 4| pages = 429–463 | doi=10.1017/s1477201907002143}}</ref> Subsequent studies found that the ''Caenagnathus'' jaws did in fact group together with other traditional caenagnathids, but not necessarily ''Chirostenotes''.<ref name=anzu/> New specimens described by Funston et al. (2015) and Funston & Currie (2020) indicated that ''Chirostenotes'' is a distinct form from ''Caenagnathus''.<ref>{{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. }}</ref>

''Chirostenotes'' was characterized by long arms ending in slender relatively straight claws, and long powerful legs with slender toes. In 2016 Paul estimated its length at {{convert|2.5|m|ft|abbr=}} and its weight at 100 kg (220 lbs), while the same year Molina-Pérez and Larramendi gave a length of 2.6 meters (8.5 ft) and a weight of 40 kg (88 lbs).<ref>{{Cite book|last=Paul|first=Gregory S.|title=The Princeton Field Guide to Dinosaurs 2nd Edition|publisher=Princeton University Press|year=2016|isbn=|location=New Jersey|pages=176}}</ref><ref>{{Cite book|last=Molina-Pérez & Larramendi|first=|title=Récords y curiosidades de los dinosaurios Terópodos y otros dinosauromorfos|publisher=Larousse|year=2016|isbn=|location=Spain|pages=271}}</ref>

In 2005 Phil Senter and J. Michael Parrish published a study on the hand function of ''Chirostenotes'' and found that its elongated second finger with its unusually straight claw may have been an adaptation to crevice probing. They suggested that ''Chirostenotes'' may have fed on soft-bodied prey that could be impaled by the second claw, such as grubs, as well as unarmored [[amphibian]]s, reptiles, and mammals.<ref>{{cite journal | last1 = Senter | first1 = P. | last2 = Parrish | first2 = J.M. | year = 2005 | title = Functional analysis of the hands of the theropod dinosaur ''Chirostenotes pergracilis'': evidence for an unusual paleoecological role | url = | journal = PaleoBios | volume = 25 | issue = | pages = 9–19 }}</ref> However, if ''Chirostenotes'' possessed the large primary feathers on its second finger that have been found in other oviraptorosaurs such as ''[[Caudipteryx]]'', it would not have been able to engage in such behavior.<ref>Naish, D. (2007). [http://scienceblogs.com/tetrapodzoology/2007/03/feathers_and_filaments_of_dino.php Feathers and Filaments of Dinosaurs, Part II] {{webarchive|url=https://web.archive.org/web/20100613235610/http://scienceblogs.com/tetrapodzoology/2007/03/feathers_and_filaments_of_dino.php |date=2010-06-13 }} Tetrapod Zoology, April 23, 2011.</ref>