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22-446: Trachodon (meaning "rough tooth") is a dubious genus of hadrosaurid dinosaur based on teeth from the Campanian -age Upper Cretaceous Judith River Formation of Montana , U.S. It is a historically important genus with a convoluted taxonomy that has been all but abandoned by modern dinosaur paleontologists . Despite being used for decades as the iconic duckbill dinosaur,

44-495: A problem with a name which has been misapplied; this specimen replaces the original holotype. In the absence of a holotype, another type may be selected, out of a range of different kinds of type, depending on the case, a lectotype or a neotype . For example, in both the ICN and the ICZN a neotype is a type that was later appointed in the absence of the original holotype. Additionally, under

66-430: A species of Trachodon are considered here. Type species : T. mirabilis Leidy, 1856 Other species: As a hadrosaurid, Trachodon would have been a large, bipedal / quadrupedal herbivore . [REDACTED] [REDACTED] [REDACTED] [REDACTED] Nomen dubium In case of a nomen dubium, it may be impossible to determine whether a specimen belongs to that group or not. This may happen if

88-415: Is a duplicate of the holotype, generally pieces from the same individual plant or samples from the same genetic individual. A holotype is not necessarily "typical" of that taxon, although ideally it is. Sometimes just a fragment of an organism is the holotype, particularly in the case of a fossil . For example, the holotype of Pelorosaurus humerocristatus (Duriatitan) , a large herbivorous dinosaur from

110-463: 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 several examples, but explicitly designated as the holotype. Under the International Code of Zoological Nomenclature (ICZN), a holotype is one of several kinds of name-bearing types . In

132-460: Is lost come into play for some recent, high-profile species descriptions in which the specimen designated as the holotype was a living individual that was allowed to remain in the wild (e.g. a new species of capuchin monkey, genus Cebus , the bee species Marleyimyia xylocopae , or the Arunachal macaque Macaca munzala ). In such a case, there is no actual type specimen available for study, and

154-504: The International Code of Zoological Nomenclature allows a new type specimen, or neotype, to be chosen for a nomen dubium in this case. 75.5. Replacement of unidentifiable name-bearing type by a neotype. When an author considers that the taxonomic identity of a nominal species-group taxon cannot be determined from its existing name-bearing type (i.e. its name is a nomen dubium ), and stability or universality are threatened thereby,

176-462: The International Code of Nomenclature for algae, fungi, and plants (ICN) and ICZN, the definitions of types are similar in intent but not identical in terminology or underlying concept. For example, the holotype for the butterfly Plebejus idas longinus is a preserved specimen of that subspecies, held by the Museum of Comparative Zoology at Harvard University . In botany and mycology , an isotype

198-461: The ICZN the commission is empowered to replace a holotype with a neotype, when the holotype turns out to lack important diagnostic features needed to distinguish the species from its close relatives. For example, the crocodile-like archosaurian reptile Parasuchus hislopi Lydekker , 1885 was described based on a premaxillary rostrum (part of the snout), but this is no longer sufficient to distinguish Parasuchus from its close relatives. This made

220-531: The Judicial Commission. The meaning of these names is uncertain. Other categories of names that may be treated in this way (rule 56a) are: In botanical nomenclature the phrase nomen dubium has no status, although it is informally used for names whose application has become confusing. In this regard, its synonym nomen ambiguum is of more frequent use. Such names may be proposed for rejection . Holotype A holotype ( Latin : holotypus )

242-500: The Judith River Formation, collected by Ferdinand Vandeveer Hayden . From these bones, he provided the first names for North American dinosaurs: Deinodon , Palaeoscincus , Trachodon , and Troodon (then spelled Troödon ). 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

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264-460: The author may request the Commission to set aside under its plenary power [Art. 81] the existing name-bearing type and designate a neotype. For example, the crocodile -like archosaurian reptile Parasuchus hislopi Lydekker , 1885 was described based on a premaxillary rostrum (part of the snout), but this is no longer sufficient to distinguish Parasuchus from its close relatives. This made

286-539: The early Cretaceous period, is a fossil leg bone stored at the Natural History Museum in London . Even if a better specimen is subsequently found, the holotype is not superseded. Under the ICN, an additional and clarifying type could be designated an epitype under article 9.8, where the original material is demonstrably ambiguous or insufficient. A conserved type (ICN article 14.3) is sometimes used to correct

308-511: 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 also found that Trachodon teeth compare well with the teeth of lambeosaurines, specifically Corythosaurus , though they also share similarities with the genus Prosaurolophus . Numerous species have been referred to this genus, mostly before World War I . Only those originally named as

330-425: 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. 149). The name is no longer in use, except in historical discussions, and is considered a nomen dubium . In 1936, paleontologist Charles Sternberg compared

352-408: The material it is based on is composed of teeth from both duckbills and ceratopsids (their teeth have a distinctive double root), and its describer, Joseph Leidy , 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 . In 1856, Joseph Leidy received fragmentary remains from

374-407: The name Parasuchus hislopi a nomen dubium . Indian-American paleontologist Sankar Chatterjee proposed that a new type specimen , a complete skeleton, be designated. The International Commission on Zoological Nomenclature considered the case and agreed to replace the original type specimen with the proposed neotype. The procedures for the designation of a new type specimen when the original

396-407: The name Parasuchus hislopi a nomen dubium . In 2001 a paleontologist proposed that a new type specimen, a complete skeleton, be designated. The International Commission on Zoological Nomenclature considered the case and agreed in 2003 to replace the original type specimen with the proposed neotype. In bacteriological nomenclature , nomina dubia may be placed on the list of rejected names by

418-432: The original type series (i. e. holotype , isotype , syntype or paratype ) is lost or destroyed. The zoological and botanical codes allow for a new type specimen, or neotype , to be chosen in this case. A name may also be considered a nomen dubium if its name-bearing type is fragmentary or lacking important diagnostic features (this is often the case for species known only as fossils). To preserve stability of names,

440-528: The possibility exists that—should there be any perceived ambiguity in the identity of the species—subsequent authors can invoke various clauses in the ICZN Code that allow for the designation of a neotype. Article 75.3.7 of the ICZN requires that the designation of a neotype must be accompanied by "a statement that the neotype is, or immediately upon publication has become, the property of a recognized scientific or educational institution, cited by name, that maintains

462-455: 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 , but as new material was described from the Rocky Mountain region, Alberta , and Saskatchewan , later authors began progressively restricting the reach of this genus. By 1942, and the publication of

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484-534: The teeth. The 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 . In the Bone Wars that followed, and their wake,

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