Editing Trachodon (section)

==History and classification==
In 1856, Joseph Leidy received fragmentary remains from the Judith River Formation, collected by [[Ferdinand Vandeveer Hayden]].  From these bones, he provided the first names for [[North America]]n dinosaurs: ''[[Deinodon]]'', ''[[Palaeoscincus]]'', ''Trachodon'', and ''[[Troodon]]'' (then spelled ''Troödon'').<ref name=JL56/><ref name="dodson2009">{{cite journal|first=Peter |last=Dodson |title=Dinosaurs in America – Joseph Leidy & the Academy of Natural Sciences | journal=American Paleontologist |volume=17 |number=2 |year=2009| page=32}}</ref> The [[type species]] of ''Trachodon'' is ''T. mirabilis''. The generic name is derived from Greek τραχυς, ''trakhys'', "rough", and όδον, ''odon'', "tooth", referring to the granulate inner surface of one of the teeth. The [[specific name (zoology)|specific name]] means "marvelous" in [[Latin]].

''Trachodon'' was based on ANSP 9260, seven unassociated teeth, one of which had double roots.  With better remains from ''[[Hadrosaurus]]'', he began to reconsider his taxonomy, and suggested, at least informally, that ''Trachodon'' should refer to the double-rooted tooth, and the other teeth should be referred to ''Hadrosaurus''.<ref name=JL68>Leidy, J. (1868). Remarks on a jaw fragment of ''Megalosaurus''. ''Proceedings of the Academy of Natural Science Philadelphia'' 20:197–200.</ref> In the [[Bone Wars]] that followed, and their wake, the taxonomy of ''Trachodon'' and its relatives became increasingly confusing,<ref name=BC07/> with one author going so far as to sink all known hadrosaur species into ''Trachodon'' except for ''[[Claosaurus agilis]]'',<ref name=JBH02>Hatcher, J.B. (1902). The genus and species of the Trachodontidae (Hadrosauridae, Claosauridae) Marsh. ''Annals of the Carnegie Museum'' 14(1):377–386.</ref> but as new material was described from the [[Rocky Mountain]] region, [[Alberta]], and [[Saskatchewan]], later authors began progressively restricting the reach of this genus.<ref name=CMS36/><ref name=CWG15>Gilmore, C.W. (1915). On the genus ''Trachodon''. ''Science'' 41:658–660.</ref>

By 1942, and the publication of the influential Lull-Wright [[monograph]] on duckbills, its [[holotype]] was regarded as "typical of all the genera of hadrosaurian dinosaur", except for the roughened margin that gave it its name, and that they regarded as due to the tooth having not been used (p.&nbsp;149).<ref name=LW42>Lull, R.S., and Wright, N.E. (1942). Hadrosaurian Dinosaurs of North America. ''Geological Society of America Special Paper 40'':1–242.</ref> The name is no longer in use, except in historical discussions, and is considered a ''nomen dubium''.<ref name=WPCJ88>Coombs, Jr., W.P. (1988). The status of the dinosaurian genus ''Diclonius'' and the taxonomic utility of hadrosaurian teeth. ''Journal of Paleontology'' 62:812–818.</ref><ref name=WH90>Weishampel, D.B., and Horner, J.R. (1990). Hadrosauridae. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). ''The Dinosauria''. University of California Press:Berkeley, 534–561.  {{ISBN|0-520-24209-2}}</ref><ref name=HWF04>Horner, J.R., Weishampel, D.B., and Forster, C.A. (2004). Hadrosauridae. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). ''The Dinosauria (second edition)''. University of California Press:Berkeley, 438–463. {{ISBN|0-520-06727-4}}</ref>

In 1936, paleontologist Charles Sternberg compared the holotype teeth of ''Trachodon mirabilis'' to those of more completely known hadrosaurids and noted that they were most similar to those of lambeosaurines.<ref name=CMS36/> It has been reported that paleontologist [[John R. Horner]] also found that ''Trachodon'' teeth compare well with the teeth of lambeosaurines, specifically ''[[Corythosaurus]]'', though they also share similarities with the genus ''[[Prosaurolophus]]''.<ref name=olshevsky1997>Olshevsky, G. (1997), [http://dml.cmnh.org/1997Aug/msg00100.html "Re: Ye Olde Duckbill Dinosaur"] {{Webarchive|url=https://web.archive.org/web/20111109133534/http://dml.cmnh.org/1997Aug/msg00100.html |date=9 November 2011 }}, discussion group, The Dinosaur Mailing List, 8 August 1997. Accessed 6 April 2013.</ref>

===Species===
Numerous species have been referred to this genus, mostly before [[World War I]]. Only those originally named as a species of ''Trachodon'' are considered here.

[[Type species]]:
''T. mirabilis'' Leidy, 1856<ref name=JL56/>

Other species:
*''T. amurense'' Riabinin, 1925<ref name=ANR25>Riabinin, A.N. (1925). A mounted skeleton of the gigantic reptile ''Trachodon amurense'', nov. sp. ''Izvest. Geol. Kom.'' 44(1):1–12. [Russian]</ref>(based on IVP AS collection, a partial skeleton from [[Upper Cretaceous]] rocks of the [[Amur River]] banks of [[Heilongjiang]] in [[northeast China]], amended to ''T. amurensis'' and now the type species of ''[[Mandschurosaurus]]'')<ref name=ANR30>Riabinin, A.N. (1930). ''Mandschurosaurus amurensis'', nov. gen., nov. sp., a hadrosaurian dinoasur from the Upper Cretaceous of Amur River. ''Mémoir II, Société Paléontologique de Russie.'' [Russian]</ref>
*''T. cantabrigiensis'' (''nomen dubium'') [[Richard Lydekker|Lydekker]], 1888<ref name=RL88>Lydekker, R. (1888). Note on a new Wealden iguanodont and other dinosaurs. ''Quarterly Journal of the Geological Society of London'' 44:46–61.</ref> (based on BMNH R.496, a [[dentary]] tooth from the [[Albian|late Albian]]-age [[Lower Cretaceous]] [[Cambridge Greensand]], [[Cambridgeshire]], [[England]], regarded as a dubious early hadrosaurid)<ref name=WH90/><ref name=HWF04/>
*''T. longiceps'' (''nomen dubium'') [[Othniel Charles Marsh|Marsh]], 1897<ref name=OCM97>Marsh, O.C. (1897). Vertebrate fossils of the Denver Basin. ''U.S. Geological Survey, Monthly'' 27:473–527.</ref> (based on YPM 616, a large right dentary with teeth from the [[Maastrichtian|late Maastrichtian]]-age Upper Cretaceous [[Lance Formation]] of [[Wyoming]], U.S., later assigned to ''[[Anatotitan]]'')<ref name=WH90/>
*''T. marginatus'' (''nomen dubium'') Lambe, 1902<ref name=LL02>Lambe, L.M. (1902). On Vertebrata of the mid-Cretaceous of the Northwest Territory. 2. New genera and species from the Belly River Series (mid-Cretaceous). ''Contributions to Canadian Paleontology'' 3:25–81.</ref> (based on NMC 419, disassociated postcranial material; later made the type species of the genus ''[[Stephanosaurus]] marginatus''<ref name=LL14>Lambe, L.M. (1914). On a new genus and species of carnivorous dinosaur from the Belly River Formation of Alberta, with a description of the skull of ''Stephanosaurus marginatus'' from the same horizon. ''Ottawa Naturalist'' 28:13–20.</ref> and then referred to ''[[Kritosaurus]]'' as ''Kritosaurus marginatus'',<ref name=CWG24>{{cite journal |last=Gilmore |first=Charles W. |author-link=Charles Whitney Gilmore |year=1924 |title=On the genus ''Stephanosaurus'', with a description of the type specimen of ''Lambeosaurus lambei'', Parks |journal=Canada Department of Mines Geological Survey Bulletin (Geological Series) |volume=38 |issue=43 |pages=29–48}}</ref> which is not supported by later reviews.<ref name=WH90/><ref name=HWF04/>)
*''T.'' (''[[Pteropelyx]]'') ''selwyni'' (''nomen dubium'') Lambe, 1902<ref name=LL02/> (based on NMC 290, a dentary with teeth, from the Dinosaur Park Formation of Alberta; too fragmentary to assign beyond Hadrosauridae)<ref name=WH90/><ref name=HWF04/>