**Dicynodontia**, of die **disinodonte**, is ’n takson van Anomodontia-terapsides wat hul oorsprong in die middel-Permperiode gehad het. Hulle het in die laat Perm oorheers en deur die Trias bestaan, met ’n paar wat moontlik tot in die vroeë Kryt oorleef het. Disinodonte was plantvreters met twee slagtande, vandaar hul naam ("twee hondetande"). Hulle was die suksesvolste en mees uiteenlopende groep terapsides wat nie soogdiere was nie, met meer as 70 bekende genera wat gewissel het van die grootte van ’n rot tot dié van ’n olifant. Hulle het onder meer voorgekom in wat vandag Suid-Afrika is.

Eienskappe
----------

’n Lewensgroot model van ’n *Diictodon*.
Die disinodonte se skedel was hoogs gespesialiseerd: lig, maar sterk. Die sinapsied-slaapopeninge aan die agterkant van die skedel was vergroot om groter kakebeenspiere te huisves. Die voorkant van die skedel en die onderste kakebeen was gewoonlik smal en, in alle gevalle buiten in ’n paar primitiewe vorme, tandloos. In plaas daarvan het die voorkant van die bek ’n benerige soort snawel gehad, soos skilpaaie en seratopsiërs. Kos is verwerk deur die terugtrekking van die onderste kakebeen wanneer die bek toegegaan het, wat ’n kragtige skeuraksie tot gevolg gehad het. Dit sou disinodonte in staat stel om taai plantmateriaal te vreet. Baie genera het ook twee slagtande gehad, wat moontlik ’n vorm van seksuele dimorfisme was.

Die lyf was kort, sterk en vaatjievormig, met sterk ledemate. Die stert was kort.

Geskiedenis
-----------

Disinodonte is sedert die middel 1800's bekend. Die Suid-Afrikaanse geoloog Andrew Geddes Bain het disinodonte in 1845 vir die eerste keer beskryf. Hy was destyds ’n opsigter vir die bou van militêre paaie vir die *Corps of Royal Engineers* en het tydens opnames baie reptielfossiele in Suid-Afrika ontdek. Hy het hierdie fossiele in 1845 in ’n brief in *Transactions of the Geological Society of London* gepubliseer en hulle "bidentals" genoem vanweë die twee prominente slagtande.

In dieselfde jaar het die Engelse paleontoloog Richard Owen twee spesies disinodonte van Suid-Afrika name gegee: *Dicynodon lacerticeps* en *Dicynodon bainii*. Omdat Bain besig was in die *Corps of Royal Engineers*, het hy Owen gevra om sy fossiele omvattender te beskryf. Owen het eers in 1876 ’n beskrywing gepubliseer in sy *Descriptive and Illustrated Catalogue of the Fossil Reptilia of South Africa in the Collection of the British Museum*. Teen dié tyd was baie meer disinodonte bekend. In 1859 het nog ’n belangrike spesie, *Ptychognathus declivis*, in Suid-Afrika ’n naam gekry. Die volgende jaar het Owen die groep "Dicynodontia" genoem.

In sy *Descriptive and Illustrated Catalogue* het Owen Bain vereer deur sy eie naam, Dicynodontia, met die naam "Bidentalia" te vervang. Dié naam was egter nie lank gewild nie en is in die volgende jare met Owen se "Dicynodontia" vervang.

Evolusie
--------

*Eodicynodon*, ’n primitiwe disinodont uit die middel-Perm van Suid-Afrika.
*Lisowicia*, ’n reusagtige disinodont uit die laat Trias van Pole.
Disinodonte het in die Guadalupium die eerste keer hul verskyning gemaak en vinnig ontwikkel totdat hulle die suksesvolste en volopste landgewerweldes van die Lopingium geword het. In dié tyd was daar ’n groot verskeidenheid ekotipes, insluitende groot, middelslag- en klein plantvreters en molagtige gatgrawers met kort ledemate.

Net vier linies het sover bekend die Perm-Trias-uitwissing oorleef; die eerste drie word elk deur ’n enkele genus verteenwoordig: *Myosaurus*, *Kombuisia* en *Lystrosaurus* (die laaste genus was die algemeenste en wydverspreidste plantvreters van die Indusium (vroegste Trias). Nie een van hulle het lank in die Trias oorleef nie. Die vierde groep was die Kannemeyeriiformes, die enigste disinodonte wat gedurende die Trias gediversifieer het. Hierdie stewige diere, van vark- tot osgrootte, was van die Olenekium tot die Ladinium wêreldwyd die volopste plantvreters. Teen die Karnium is hulle deur Traversodontidae-sinodonte en Rhynchosauria-reptiele vervang. Gedurende die Norium (middel van die laat Trias) het hulle getalle begin afneem, moontlik weens toenemende droogheid. Die rol van groot plantvreters is oorgeneem deur souropodomorfe-dinosourusse.

Fossiele van die disinodont *Lisowicia bojani*, wat omtrent so groot soos ’n Asiatiese olifant was, is in Pole ontdek en dui daarop dat disinodonte ten minste tot in die Norium of vroegste Rhaetium (laat Trias) orleef het; dit was ook die grootste bekende disinodontspesie.

### Filogenie

Onder is ’n kladogram wat aangepas is vanaf Angielczyk en Rubidge (2010), wat die filogeniese verwantskappe van Dicynodontia aandui:

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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| **Dicynodontia**  | 

|  |  |
| --- | --- |
|  | *Eodicynodon* |
|  |
|  | 

|  |  |
| --- | --- |
|  | *Colobodectes* |
|  |
|  | 

|  |  |
| --- | --- |
|  | *Lanthanostegus* |
|  |
|  | 

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  Pylaecephalidae  | 

|  |  |
| --- | --- |
|  | *Robertia* |
|  |
|  | *Diictodon* |
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|  | *Prosictodon* |
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|  | 

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| --- | --- |
|  | *Chelydontops* |
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|  | *Endothiodon* |
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| --- | --- |
|  | *Pristerodon* |
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|  | 

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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  Emydopoidea  | 

|  |  |
| --- | --- |
|  | *Emydops* |
|  |
|  | 

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  | 

|  |  |
| --- | --- |
|  | *Myosaurus* |
|  |
|  Kingoriidae  | 

|  |  |
| --- | --- |
|  | *Dicynodontoides* |
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|  | *Kombuisia* |
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|  Cistecephalidae  | 

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| --- | --- |
|  | *Cistecephalus* |
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| --- | --- |
|  | *Cistecephaloides* |
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|  | *Kawingasaurus* |
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|  Pristerodontia  | 

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| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  | 

|  |  |
| --- | --- |
|  | *Interpresosaurus* |
|  |
|  | *Elph* |
|  |
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|  |  |
| --- | --- |
|  | *Rhachiocephalus* |
|  |
|  | 

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
|  Cryptodontidae  | 

|  |  |
| --- | --- |
|  | *Oudenodon* |
|  |
|  | 

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| --- | --- |
|  | *Tropidostoma* |
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|  | *Australobarbarus* |
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|  Geikiidae  | 

|  |  |
| --- | --- |
|  | *Odontocyclops* |
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| --- | --- |
|  | *Idelesaurus* |
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|  Dicynodontoidea  | 

|  |  |
| --- | --- |
|  | *Katumbia* |
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|  | 

|  |  |
| --- | --- |
|  | *Delectosaurus* |
|  |
|  | 

|  |  |
| --- | --- |
|  | *Dicynodon* |
|  |
|  | 

|  |  |
| --- | --- |
|  | Lystrosauridae |
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| --- | --- |
|  | Kannemeyeriiformes |
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|  | *Vivaxosaurus* |
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