''Trachodon'' (meaning "rough tooth") is a dubious

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

hadrosaurid Hadrosaurids (), also hadrosaurs or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod fami ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

based on

teeth A tooth (: teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...

from the

Campanian The Campanian is the fifth of six ages of the Late Cretaceous epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campa ...

-age

Upper Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cret ...

Judith River Formation of

Montana Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...

, U.S.Leidy, J. (1856). "Notice of remains of extinct reptiles and fishes, discovered by F. V. Hayden in the Bad Lands of the Judith River, Nebraska Territories." ''Proceedings of the Academy of Natural Science Philadelphia'', 8(25 March): 72–73. It is a historically important genus with a convoluted

taxonomy image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...

that has been all but abandoned by modern dinosaur

paleontologist Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geolo ...

s.Creisler, B.S. (2007). Deciphering duckbills. in: K. Carpenter (ed.), ''Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs''. Indiana University Press: Bloomington and Indianapolis, 185–210. Despite being used for decades as the iconic duckbill dinosaur, the material it is based on is composed of teeth from both duckbills and

ceratopsid Ceratopsidae (sometimes spelled Ceratopidae) is a family of ceratopsian dinosaurs including ''Triceratops'', '' Centrosaurus'', and '' Styracosaurus''. All known species were quadrupedal herbivores from the Upper Cretaceous. All but one species are ...

s (their teeth have a distinctive double rootHatcher, J.B., Marsh, O.C. and Lull, R.S. (1907). ''The Ceratopsia''. Government Printing Office, Washington, D.C., 300 pp. ), and its describer,

Joseph Leidy Joseph Mellick Leidy (September 9, 1823 – April 30, 1891) was an American paleontologist, parasitologist and anatomist. Leidy was professor of anatomy at the University of Pennsylvania, later becoming a professor of natural history at Swarth ...

, came to recognize the difference and suggested limiting the genus to what would now be seen as ceratopsid teeth. Restricted to the duckbill teeth, it may have been a lambeosaurine.Sternberg, C.M. (1936). The systematic position of ''Trachodon''. ''Journal of Paleontology'' 10(7):652–655.

History and classification

In 1856, Joseph Leidy received fragmentary remains from the Judith River Formation, collected by

Ferdinand Vandeveer Hayden Ferdinand Vandeveer Hayden (September 7, 1829 – December 22, 1887) was an American geologist noted for his pioneering surveying expeditions of the Rocky Mountains in the late 19th century. He was also a physician who served with the Union A ...

. From these bones, he provided the first names for

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

n dinosaurs: '' Deinodon'', '' Palaeoscincus'', ''Trachodon'', and ''

Troodon ''Troodon'' ( ; ''Troödon'' in older sources) is a controversial genus of relatively small, bird-like theropod dinosaurs definitively known from the Campanian age of the Late Cretaceous period (about 77 million years ago). It includes at l ...

'' (then spelled ''Troödon''). The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

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 means "marvelous" in

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

. ''Trachodon'' was based on ANSP 9260, seven unassociated teeth, one of which had double roots. With better remains from ''

Hadrosaurus ''Hadrosaurus'' (; ) is a genus of hadrosaurid ornithopod dinosaurs that lived in North America during the Late Cretaceous Period in what is now the Woodbury Formation in New Jersey about 83.6 to 77.9 Ma. The holotype specimen was found in flu ...

'', 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''.Leidy, J. (1868). Remarks on a jaw fragment of ''Megalosaurus''. ''Proceedings of the Academy of Natural Science Philadelphia'' 20:197–200. In the

Bone Wars The Bone Wars, also known as the Great Dinosaur Rush, was a period of intense and ruthlessly competitive fossil hunting and discovery during the Gilded Age of American history, marked by a heated rivalry between Edward Drinker Cope (of the Aca ...

that followed, and their wake, the taxonomy of ''Trachodon'' and its relatives became increasingly confusing, with one author going so far as to sink all known hadrosaur species into ''Trachodon'' except for '' Claosaurus agilis'',Hatcher, J.B. (1902). The genus and species of the Trachodontidae (Hadrosauridae, Claosauridae) Marsh. ''Annals of the Carnegie Museum'' 14(1):377–386. but as new material was described from the

Rocky Mountain The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of Western Canada, to New Mexico in ...

region,

Alberta Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...

, and

Saskatchewan Saskatchewan is a Provinces and territories of Canada, province in Western Canada. It is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and to the south by the ...

, later authors began progressively restricting the reach of this genus.Gilmore, C.W. (1915). On the genus ''Trachodon''. ''Science'' 41:658–660. By 1942, and the publication of the influential Lull-Wright

monograph A monograph is generally a long-form work on one (usually scholarly) subject, or one aspect of a subject, typically created by a single author or artist (or, sometimes, by two or more authors). Traditionally it is in written form and published a ...

on duckbills, its

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

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. 149).Lull, R.S., and Wright, N.E. (1942). Hadrosaurian Dinosaurs of North America. ''Geological Society of America Special Paper 40'':1–242. The name is no longer in use, except in historical discussions, and is considered a ''nomen dubium''.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.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. 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. 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. It has been reported that paleontologist

John R. Horner John is a common English name and surname: * John (given name) * John (surname) John may also refer to: New Testament Works * Gospel of John, a title often shortened to John * First Epistle of John, often shortened to 1 John * Second Ep ...

also found that ''Trachodon'' teeth compare well with the teeth of lambeosaurines, specifically ''

Corythosaurus ''Corythosaurus'' (; ) is a genus of hadrosaurid "duck-billed" dinosaur from the Late Cretaceous Period (geology), period, about 77–75.7 million years ago, in what is now Laramidia, western North America. Its name is derived from the Anci ...

'', though they also share similarities with the genus ''

Prosaurolophus ''Prosaurolophus'' (; meaning "before ''Saurolophus''", in comparison to the later dinosaur with a similar head crest) is a genus of hadrosaurid (or duck-billed) dinosaur from the Late Cretaceous of North America. It is known from the remains of ...

''.Olshevsky, G. (1997)
"Re: Ye Olde Duckbill Dinosaur"
, discussion group, The Dinosaur Mailing List, 8 August 1997. Accessed 6 April 2013.

Species

Numerous species have been referred to this genus, mostly before

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

. Only those originally named as a species of ''Trachodon'' are considered here.

Type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

: ''T. mirabilis'' Leidy, 1856 Other species: *''T. amurense'' Riabinin, 1925Riabinin, A.N. (1925). A mounted skeleton of the gigantic reptile ''Trachodon amurense'', nov. sp. ''Izvest. Geol. Kom.'' 44(1):1–12. ussian/ref>(based on IVP AS collection, a partial skeleton from

rocks of the

Amur River The Amur River () or Heilong River ( zh, s=黑龙江) is a perennial river in Northeast Asia, forming the natural border between the Russian Far East and Northeast China (historically the Outer and Inner Manchuria). The Amur ''proper'' is ...

banks of

Heilongjiang Heilongjiang is a province in northeast China. It is the northernmost and easternmost province of the country and contains China's northernmost point (in Mohe City along the Amur) and easternmost point (at the confluence of the Amur and Us ...

northeast China Northeast China () is a geographical region of China, consisting officially of three provinces Liaoning, Jilin and Heilongjiang. The heartland of the region is the Northeast China Plain, the largest plain in China with an area of over . The regi ...

, amended to ''T. amurensis'' and now the type species of '' Mandschurosaurus'')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.'' ussian/ref> *''T. cantabrigiensis'' (''nomen dubium'') Lydekker, 1888Lydekker, R. (1888). Note on a new Wealden iguanodont and other dinosaurs. ''Quarterly Journal of the Geological Society of London'' 44:46–61. (based on BMNH R.496, a

dentary In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone ...

tooth from the late Albian-age

Lower Cretaceous Lower may refer to: * ''Lower'' (album), 2025 album by Benjamin Booker * Lower (surname) * Lower Township, New Jersey *Lower Receiver (firearms) * Lower Wick Gloucestershire, England See also * Nizhny {{Disambiguation ...

Cambridge Greensand The Cambridge Greensand is a geological unit in England whose strata are earliest Cenomanian in age. It lies above the erosive contact between the Gault Formation and the Chalk Group in the vicinity of Cambridgeshire, and technically forms the l ...

Cambridgeshire Cambridgeshire (abbreviated Cambs.) is a Ceremonial counties of England, ceremonial county in the East of England and East Anglia. It is bordered by Lincolnshire to the north, Norfolk to the north-east, Suffolk to the east, Essex and Hertfor ...

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

, regarded as a dubious early hadrosaurid) *''T. longiceps'' (''nomen dubium'')

Marsh In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...

, 1897Marsh, O.C. (1897). Vertebrate fossils of the Denver Basin. ''U.S. Geological Survey, Monthly'' 27:473–527. (based on YPM 616, a large right dentary with teeth from the late Maastrichtian-age Upper Cretaceous

Lance Formation The Lance (Creek) Formation is a division of Late Cretaceous (dating to about 69–66 Ma) rocks in the western United States. Named after Lance Creek, Wyoming, the microvertebrate fossils and dinosaurs represent important components of the lates ...

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

, U.S., later assigned to '' Anatotitan'') *''T. marginatus'' (''nomen dubium'') Lambe, 1902Lambe, 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. (based on NMC 419, disassociated postcranial material; later made the type species of the genus '' Stephanosaurus marginatus''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. and then referred to '' Kritosaurus'' as ''Kritosaurus marginatus'', which is not supported by later reviews.) *''T.'' ('' Pteropelyx'') ''selwyni'' (''nomen dubium'') Lambe, 1902 (based on NMC 290, a dentary with teeth, from the Dinosaur Park Formation of Alberta; too fragmentary to assign beyond Hadrosauridae)

Paleobiology

As a hadrosaurid, ''Trachodon'' would have been a large,

biped Bipedalism is a form of terrestrial locomotion where an animal moves by means of its two rear (or lower) limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' ' ...

al/

quadruped Quadrupedalism is a form of locomotion in which animals have four legs that are used to bear weight and move around. An animal or machine that usually maintains a four-legged posture and moves using all four legs is said to be a quadruped (fr ...

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

References

{{Taxonbar, from=Q1060870 Hadrosauridae Dinosaur genera Campanian dinosaurs Judith River Formation Taxa named by Joseph Leidy Fossil taxa described in 1856 Dinosaurs of the United States