''Diademodon'' is an extinct
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 ...
of
cynodont
Cynodontia () is a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 Megaannum, mya), and extensively diversified after the Permian–Triassic extinction event. Mammals are cynodonts, as are their extin ...
s. It was about long.
Discovery

Harry Seeley had found his fossil in the
Burgersdorp Formation of the
Beaufort Group in the
Karoo Basin of South Africa. As late as 1988, ''Diademodon'' had been considered a Gomphodont due to its transversely expanded cheek teeth, however, it has since been placed in the Cynodont order due to significant differences in skull morphology. Additional species were named by paleontologist A. S. Brink in 1979, although they are now considered
synonym
A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...
s of 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 ...
''Diademodon tetragonus''. Fossils of the ''Diademodon tetragonus'' have more recently been found in the
Omingonde Formation
The Omingonde Formation is an Early Triassic, Early to Middle Triassic (Anisian to Ladinian) geologic Formation (geology), formation, part of the Karoo Supergroup, in the western Otjozondjupa Region and northeastern Erongo Region of north-central N ...
of
Namibia
Namibia, officially the Republic of Namibia, is a country on the west coast of Southern Africa. Its borders include the Atlantic Ocean to the west, Angola and Zambia to the north, Botswana to the east and South Africa to the south; in the no ...
, the
Fremouw Formation of
Antarctica
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...
, the
Ntawere Formation of
Zambia
Zambia, officially the Republic of Zambia, is a landlocked country at the crossroads of Central Africa, Central, Southern Africa, Southern and East Africa. It is typically referred to being in South-Central Africa or Southern Africa. It is bor ...
and the
Río Seco de la Quebrada Formation in
Mendoza Province
Mendoza (), officially the Province of Mendoza, is a province of Argentina, in the western central part of the country in the Cuyo region. It borders San Juan to the north, La Pampa and Neuquén to the south, San Luis to the east, and the r ...
,
Argentina
Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...
.
Although ''Diademodon'' is the most well accepted name for the genera to date, it was originally named ''Cynochampsa laniarius'' by Owen in 1860. The proposed name change occurred in 1982, where Grine defended the name proposed by
Harry Seeley
Harry Govier Seeley (18 February 1839 – 8 January 1909) was a British paleontologist.
Early life
Seeley was born in London on 18 February 1839, the second son of Richard Hovill Seeley, a goldsmith, and his second wife Mary Govier. When his fa ...
: ''Diademodon tetragonus'' and to be place in the group Therapsida, which was a group Owen had tiptoed around in his works on paleontology. Though Harry Govier Seeley had named ''Diademodon'' in 1894, which was after Owen had dubbed the genus ''Cynochampsa'', Seeley had not realized the two were one and the same as the fossil that Owen named was claimed to have been found in a claystone nodule in the Renosterberg Mountains. A later paleontologist explored the same area where the fossil was claimed to have been found and declared no evidence of ''Cynognathus'' fossils.
Classification
Until a study performed by Botha and colleagues in 2005, the post cranial skeletons of ''Diademodon'' and its close relative, ''Cynognathus'' were near to impossible to distinguish. This was due to similarities in post cranial skeletons between the two genera and their identical unearthing sites.
With new technology, the axial skeletons of ''Diademodon'' and ''Cynognathus'' were able to be teased apart. It was found that Diademodon had cylindrical growth patterns which may have been associated with changing seasons, whereas ''Cynognathus'' growth patterns were rapid and sustained.
Palaeobiology
Diet

For a long time ''Diademodon'' was largely characterized as being herbivorous, yet there is evidence which suggests it may have been omnivorous, there has not yet been a clear conclusion to the specifics of ''Diademodon’s'' diet.
The reason for the unclear conclusions may be due to ''Diademodon’s'' counter intuitive teeth. The canines in ''Diademodon'' were very pronounced yet the post canines were thought to be adapted for vegetation.
Through the examination of stable light isotopes of oxygen extracted from ''Diademodon'' fossils, it was able to be deduced that the organism relied heavily on water from sources other than leaves, namely streams, rivers, lakes, snowmelt and other such sources. It was these sources which allowed for a multitude of inferences to be made of ''Diademodon’s'' ecology. ''Diademodon’s'' preferred habitat was thought to have included much canopy cover and a cooler environment. These assumptions were inferred from the low carbon values found in extracted tissues. Another interpretation of this data was that ''Diademodon'' may have had hippo-like behavior, that is, it remained in deep pools of water during day hours and only left its aquatic environment at night to forage for food. This was interpreted from low oxygen values found in tissue samples. However, this idea was put to rest as ''Diademodon'' did not morphologically or isotopically reveal any adaptations for long term aquatic life. Its bone oxygen levels did not match those of other semiaquatic organisms, such as the hippopotamus. A third suggested possibility was that ''Diademodon'' may have been close to readily available water sources, though did not spend the majority of its life in them. It may have munched on shallow water seaweed, which is known to have lower oxygen content.
See also
* ''
Cynognathus
''Cynognathus'' is an extinct genus of large-bodied cynodontian therapsids that lived in the Middle Triassic. It is known from a single species, ''Cynognathus crateronotus''. ''Cynognathus'' was a predator closely related to mammals and had a s ...
''
* ''
Trirachodon
''Trirachodon'' (Greek: "three ridge tooth") is an extinct genus of cynodonts. Fossils have been found in the ''Cynognathus'' Assemblage Zone of the Beaufort Group in South Africa and the Omingonde Formation of Namibia, dating back to the Earl ...
''
References
{{Taxonbar, from=Q332891
Cynognathia
Middle Triassic synapsids of Africa
Triassic Namibia
Fossils of Namibia
Omingonde Formation
Triassic South Africa
Fossils of South Africa
Triassic Tanzania
Fossils of Tanzania
Fossils of Zambia
Middle Triassic synapsids of South America
Triassic Argentina
Fossils of Argentina
Triassic Antarctica
Fossils of Antarctica
Fossil taxa described in 1894
Taxa named by Harry Seeley