''Australosyodon'' is an extinct genus of

dinocephalia Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinoceph ...

therapsid Therapsida is a major group of eupelycosaurian synapsids that includes mammals, their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented mor ...

s from the middle

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Pale ...

of South Africa. The first fossil was discovered in the 1980s near the village of

Prince Albert Road Prince Albert Road is a village located in Laingsburg Local Municipality, Western Cape. History The village of Prince Albert Road owes its existence to the route chosen by Prime Minister John Molteno, in 1872, for the Cape Government Railways's w ...

in the

Karoo The Karoo ( ; from the Afrikaans borrowing of the South Khoekhoe !Orakobab or Khoemana word ''ǃ’Aukarob'' "Hardveld") is a semi- desert natural region of South Africa. No exact definition of what constitutes the Karoo is available, so its ...

region of

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring count ...

. The genus is closely related to the genus ''

Syodon ''Syodon'' is an extinct genus of dinocephalian therapsids that lived approximately 267-260 million years ago during the middle Permian period of the Paleozoic era. These therapsids, located in Russia were initially believed to be true mammals ...

'', found in the Russian Ischejewo fauna, and is thus regarded as the earliest example of an

anteosaurid Anteosauridae is an extinct family of large carnivorous dinocephalian therapsids that are known from the Middle Permian of Asia, Africa, and South America.These animals were by far the largest predators of the Permian period, with skulls reachin ...

Dinocephalia Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinoceph ...

outside of Russia. ''Australosyodon'' fossils have been recovered from the

Eodicynodon Assemblage Zone The ''Eodicynodon'' Assemblage Zone is a tetrapod assemblage zone or biozone which correlates to the Abrahamskraal Formation, Adelaide Subgroup of the Beaufort Group, a fossiliferous and geologically important geological Group of the Karoo Super ...

, the lowest

bank A bank is a financial institution that accepts deposits from the public and creates a demand deposit while simultaneously making loans. Lending activities can be directly performed by the bank or indirectly through capital markets. Becau ...

of the South African

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 underli ...

, indicating the presence of primitive early therapsids in the southern hemisphere. The genus was first described by Bruce S. Rubidge in 1994.

Description

''Australosyodon'' was a medium-sized dinocephalian. The skull was high and narrow, with a length of 26 cm, indicating a total body length of approximately 1.8 m (6 ft). The top of the skull displayed the thickening typical of dinocephalians. Overall there are many similarities to the skull of ''Syodon'', although some minor differences in shape and in the extent of

pachyostosis Pachyostosis is a non-pathological condition in vertebrate animals in which the bones experience a thickening, generally caused by extra layers of lamellar bone. It often occurs together with bone densification (osteosclerosis), reducing inner ca ...

are present. The

fang A fang is a long, pointed tooth. In mammals, a fang is a modified maxillary tooth, used for biting and tearing flesh. In snakes, it is a specialized tooth that is associated with a venom gland (see snake venom). Spiders also have external fan ...

s were laterally compressed and featured a rearward-facing central cutting edge. Shape, number and arrangement of teeth are among the characteristics that allow distinguishing ''Australosyodon'' from ''Syodon''.

Classification

''Australosyodon'' is regarded as a very primitive anteosaurid dinocephalian and as first known representative of that group in the southern hemisphere. Like ''Syodon'', ''Australosyodon'' lacked the features typical for the more

apomorphic In phylogenetics, an apomorphy (or derived trait) is a novel character or character state that has evolved from its ancestral form (or plesiomorphy). A synapomorphy is an apomorphy shared by two or more taxa and is therefore hypothesized to have ...

members of the

anteosauridae Anteosauridae is an extinct family of large carnivorous dinocephalian therapsids that are known from the Middle Permian of Asia, Africa, and South America.These animals were by far the largest predators of the Permian period, with skulls reaching ...

, e.g. the boss on the lower mandible found in ''

Anteosaurus ''Anteosaurus'' (meaning "Antaeus reptile") is an extinct genus of large carnivorous dinocephalian synapsid. It lived at the end of the Guadalupian (= Middle Permian) during the Capitanian stage, about 265 to 260 million years ago in what is now ...

'' or ''

Titanophoneus ''Titanophoneus'' ("titanic murderer") is an extinct genus of carnivorous dinocephalian therapsid from the Middle Permian. It is classified within the family Anteosauridae. The type species is ''Titanophoneus potens''. Remains of ''Titanophoneus' ...

''. These two closely related genera have therefore been combined into a subgenus

Syodontinae Syodontinae is a group of dinocephalian therapsids. It is one of two subfamilies in the family Anteosauridae, the other being Anteosaurinae. They are known from the Middle Permian Period of what is now Russia and South Africa. One of the best kn ...

Chart

References

{{Taxonbar, from=Q142963 Anteosaurs Prehistoric therapsid genera Guadalupian synapsids of Africa Fossil taxa described in 1994

Description

Classification

Chart

See also

References