# Predentary

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[[Image:Edmontosaurus_skull.jpg|right|thumb|300px|''[Edmontosaurus](/source/Edmontosaurus)'' [skull](/source/skull) with a visible predentary]]
A '''predentary''' is an ossification situated on the front of the [lower jaw](/source/Jaw), which extended the dentary (the main lower jaw bone). A predentary bone has evolved independently in two groups of [teleost](/source/teleost) fish, [Istiophoridae](/source/Istiophoridae) and [Saurodontidae](/source/Saurodontidae),<ref name="Fierstine1968"/><ref name="AlvaradoOrtega2010"/> and two dinosaur groups, [ornithischians](/source/ornithischians) and [ornithuromorph](/source/ornithuromorph) birds.<ref name="Bailleul2019"/>

A predentary is found in all but perhaps the earliest ornithischian dinosaurs. Its occurrence led [Othniel Marsh](/source/Othniel_Marsh) to propose naming the group Predentata,<ref name="Marsh1894"/> though this is now considered a synonym of Ornithischia.<ref name="Norman2022"/> The predentary coincided with the [premaxilla](/source/premaxilla) in the [upper jaw](/source/Jaw). Together, they formed a [beak](/source/beak)-like apparatus used to clip off plant material. In [ceratopsian](/source/ceratopsian) dinosaurs, it opposes the [rostral bone](/source/rostral_bone). The predentary would have allowed the dentaries to move slightly independently of each other, aiding chewing.<ref name="Nabavizadeh2016"/> The toothless, beaked tip of the dentary in [silesaurids](/source/silesaurids) may have been a predecessor of the ornithischian predentary.<ref name="Ferigolo2007"/><ref name="Norman2022"/>

The avian predentary arose in the clade Ornithuromorpha,<ref name="Bailleul2019"/> and is absent from earlier bird lineages such as [enantiornitheans](/source/enantiornitheans) and ''[Archaeopteryx](/source/Archaeopteryx)''.<ref name="Zhou2011"/> It has been interpreted as a [sesamoid bone](/source/sesamoid_bone).<ref name="Bailleul2019"/> Members of [Neornithes](/source/Neornithes), the group containing all modern birds, lack a predentary, unlike other ornithuromorphs, possibly because the fusion of the mandibular symphysis and loss of teeth rendered the predentary unnecessary.<ref name="Crane2025"/> Due to the independent origins of the predentary in ornithischians and birds, the avian predentary has alternatively been called the '''intersymphyseal ossificiation''',<ref name="O'Connor2009"/> although this term is not entirely appropriate because it is not strictly intersymphyseal in position.<ref name="Bailleul2019"/>

An ossified predentary has arisen in two lineages of fish, the extinct Saurodontidae and the extant Istiophoridae (marlin), and a cartilaginous pre-mandibular element occurs in several other groups.<ref name="Bardack1969"/> The istiophorid predentary differs from other predentaries in bearing denticles.<ref name="Bardack1969"/> 

==References==
<references>
<ref name="AlvaradoOrtega2010">{{Cite journal| doi = 10.1111/j.1475-4983.2010.00935.x| issn = 0031-0239 | eissn = 1475-4983| volume = 53| issue = 2| pages = 297–306| last1 = Alvarado-Ortega| first1 = Jesús| last2 = Brito| first2 = Paulo M.| title = A new ichthyodectiform (Actinopterygii, Teleostei) from the Lower Cretaceous Marizal Formation, north-east Brazil| journal = Palaeontology| date = 2010 | bibcode = 2010Palgy..53..297A }}</ref>
<ref name="Bailleul2019">{{Cite journal| doi = 10.1073/pnas.1911820116| issn = 0027-8424 | eissn = 1091-6490| volume = 116| issue = 49| pages = 24696–24706| last1 = Bailleul| first1 = Alida M.| last2 = Li| first2 = Zhiheng| last3 = O’Connor| first3 = Jingmai| last4 = Zhou| first4 = Zhonghe| title = Origin of the avian predentary and evidence of a unique form of cranial kinesis in Cretaceous ornithuromorphs| journal = Proceedings of the National Academy of Sciences| date = 2019-12-03 | doi-access = free | pmid = 31740590 | bibcode = 2019PNAS..11624696B | pmc = 6900542}}</ref>
<ref name="Bardack1969">{{Cite journal| volume = 16| issue = 12| last1 = Bardack| first1 = David| last2 = Sprinkle| first2 = Gloria| title = Morphology and relationships of saurocephalid fishes| journal = Fieldiana Geology| date = 1969-08-28}}</ref>
<ref name="Crane2025">{{Cite journal| doi = 10.1186/s12862-025-02487-4| issn = 2730-7182| last1 = Crane| first1 = Abi H.| last2 = Benito| first2 = Juan| last3 = Chen| first3 = Albert| last4 = Ksepka| first4 = Daniel T.| last5 = Field| first5 = Daniel J.| title = Mandibular morphology clarifies phylogenetic relationships near the origin of crown birds| journal = BMC Ecology and Evolution| date = 2025-12-25| doi-access = free| pmid = 41449345}}</ref>
<ref name="Ferigolo2007">{{Cite journal| doi = 10.1080/08912960600845767| issn = 0891-2963 | eissn = 1029-2381| volume = 19| issue = 1| pages = 23–33| last1 = Ferigolo| first1 = Jorge| last2 = Langer| first2 = Max C.| title = A Late Triassic dinosauriform from south Brazil and the origin of the ornithischian predentary bone| journal = Historical Biology| date = 2007 | bibcode = 2007HBio...19...23F }}</ref>
<ref name="Fierstine1968">{{Cite journal| volume = 67| issue = 1| pages = 29–39| last1 = Fierstine| first1 = Harry L.| last2 = Applegate| first2 = Shelton P.| title = Billfish remains from southern California with remarks on the importance of the predentary bone| journal = Bulletin of the Southern California Academy of Sciences| date = 1968}}</ref>
<ref name="Marsh1894">{{Cite journal| doi = 10.2475/ajs.s3-48.283.85| issn = 0002-9599| volume = s3-48| issue = 283| pages = 85–90| last = Marsh| first = O. C.| title = The typical Ornithopoda of the American Jurassic| journal = American Journal of Science| date = 1894-07-01| bibcode = 1894AmJS...48...85M}}</ref>
<ref name="Nabavizadeh2016">{{Cite journal| doi = 10.1002/ar.23455| issn = 1932-8486| volume = 299| issue = 10| pages = 1358–1388| last1 = Nabavizadeh| first1 = Ali| last2 = Weishampel| first2 = David B.| title = The predentary bone and its significance in the evolution of feeding mechanisms in ornithischian dinosaurs| journal = The Anatomical Record| date = 2016-08-04| pmid = 27490958}}</ref>
<ref name="Norman2022">{{Cite journal| doi = 10.1093/zoolinnean/zlac062| issn = 0024-4082| pages = –062| last1 = Norman| first1 = David B| last2 = Baron| first2 = Matthew G| last3 = Garcia| first3 = Mauricio S| last4 = Müller| first4 = Rodrigo Temp| title = Taxonomic, palaeobiological and evolutionary implications of a phylogenetic hypothesis for Ornithischia (Archosauria: Dinosauria)| journal = Zoological Journal of the Linnean Society| date = 2022-09-01| volume = 196| issue = 4}}</ref>
<ref name="O'Connor2009">{{Cite journal| volume = 29| issue = 1| pages = 188–204| last1 = O'Connor| first1 = Jingmai K.| last2 = Wang| first2 = Xuri| last3 = Chiappe| first3 = Luis M.| last4 = Gao| first4 = Chunling| last5 = Meng| first5 = Qingjin| last6 = Cheng| first6 = Xiaodong| last7 = Liu| first7 = Jinyuan| title = Phylogenetic support for a specialized clade of Cretaceous enantiornithine birds with information from a new species| journal = Journal of Vertebrate Paleontology| date = 2009| doi = 10.1080/02724634.2009.10010371| jstor = 20491078| bibcode = 2009JVPal..29..188O}}</ref>
<ref name="Zhou2011">{{Cite journal| doi = 10.1080/14772019.2010.504080| issn = 1477-2019 | eissn = 1478-0941| volume = 9| issue = 1| pages = 25–31| last1 = Zhou| first1 = Zhonghe| last2 = Martin| first2 = Larry D.| title = Distribution of the predentary bone in Mesozoic ornithurine birds| journal = Journal of Systematic Palaeontology| date = 2011-02-28 | bibcode = 2011JSPal...9...25Z }}</ref>
</references>

{{Tetrapod osteology|S.}}
Category:Dinosaur anatomy

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Adapted from the Wikipedia article [Predentary](https://en.wikipedia.org/wiki/Predentary) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Predentary?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.