''Diademodon'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

cynodont The cynodonts () (clade Cynodontia) are a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 mya), and extensively diversified after the Permian–Triassic extinction event. Cynodonts had a wide variety ...

s. It was about long.

Discovery

Harry Seeley had found his fossil in the

Burgersdorp Formation The ''Cynognathus'' Assemblage Zone is a tetrapod biozone utilized in the Karoo Basin of South Africa. It is equivalent to the Burgersdorp Formation, the youngest lithostratigraphic formation in the Beaufort Group, which is part of the fossilife ...

of the

Beaufort Group The Beaufort Group is the third of the main subdivisions of the Karoo Supergroup in South Africa. It is composed of a lower Adelaide Subgroup and an upper Tarkastad Subgroup. It follows conformably after the Ecca Group and unconformably underlie ...

in the

Karoo Basin The Karoo Supergroup is the most widespread stratigraphy, stratigraphic unit in Africa south of the Kalahari Desert. The group (stratigraphy), supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Pennsylvan ...

of South Africa. As late as 1988, ''Diademodon'' had been considered a Gophodont 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 exactly 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 all ...

s of the

type species In 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 species that contains the biological type specimen ...

''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 ...

Namibia Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...

, 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, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...

, 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, although it is typically referred to as being in Southern Africa at its most cent ...

and the Río Seco de la Quebrada Formation in Mendoza Province,

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

. 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 fat ...

: ''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 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.

References

{{Taxonbar, from=Q332891 Cynognathians Prehistoric cynodont genera 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

Discovery

Classification

Palaeobiology

Diet

See also

References