''Antarctosuchus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

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 ...

of capitosauroid

temnospondyl Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order (biology), order of small to giant tetrapods—often considered Labyrinthodontia, primitive amphi ...

known from the

Middle Triassic In the geologic timescale, the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided in chronostratigraphy. The Middle Triassic spans the time between Ma and ...

upper

Fremouw Formation The Fremouw Formation is a Triassic-age rock formation in the Transantarctic Mountains of Antarctica. It contains the oldest known fossils of tetrapods from Antarctica, including synapsids, reptiles and amphibians. Fossilized trees have also been ...

in the

Transantarctic Mountains The Transantarctic Mountains (abbreviated TAM) comprise a mountain range of uplifted (primarily sedimentary rock, sedimentary) rock in Antarctica which extend, with some interruptions, across the continent from Cape Adare in northern Victoria La ...

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 ...

. It contains a single species, ''Antarctosuchus polyodon''. Antarctosuchus (43288383991)

Discovery

''Antarctosuchus'' was named by Christian A. Sidor, J. Sébastien Steyer and William R. Hammer in

2014 File:2014 Events Collage.png, From top left, clockwise: Stocking up supplies and personal protective equipment (PPE) for the Western African Ebola virus epidemic; Citizens examining the ruins after the Chibok schoolgirls kidnapping; Bundles of wat ...

and 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 ...

is ''Antarctosuchus polyodon''. The generic name refers to

, where the only known specimen was collected, and ''suchus'', a common suffix for

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

ized from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

''souchos'', an Egyptian crocodile god. The specific name, ''polyodon'', is derived from the Greek πολύς (''polús'') "much", "many" and ὀδών (''odon''), "tooth", in reference to its unique

teeth A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...

morphology. ''Antarctosuchus'' is known solely from its

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

, a large and relatively complete

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...

. It was collected form the upper

in the central

, dating to the

. To date, ''Antarctosuchus polyodon'' is the only other

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

species from the formation apart from '' Kryostega collinsoni'', although indeterminate remains referred to benthosuchids and a cranial fragment assigned to ''

Parotosuchus ''Parotosuchus'' is an extinct genus of capitosaurian temnospondyl amphibians within the family Mastodonsauridae. Fossils are known from the Early Triassic of Europe, Africa, Australia, and Antarctica. It was about long and likely lived in aqua ...

sp.'' have also been collected.

Description

As its specific name suggests, ''Antarctosuchus polyodon'' is distinguished by the possession of numerous, extremely small

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The t ...

ry,

palatine A palatine or palatinus (in Latin; plural ''palatini''; cf. derivative spellings below) is a high-level official attached to imperial or royal courts in Europe since Roman times.

, and ectopterygoid teeth, a dental pattern that suggests specialization on small prey, possibly

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s. Other

autapomorphic In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to t ...

features of this taxon are a parachoanal tooth row that extends far posterior to the choana and occipital condyles which are set close to the midline. ''Antarctosuchus'' possesses a relatively flat skull, low

occiput The occipital bone () is a cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobes of the cereb ...

and well-developed sensory canals, suggesting an aquatic lifestyle. A

phylogenetic analysis In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

places ''Antarctosuchus'' within

Capitosauroidea The Mastodonsauroidea are an extinct superfamily of temnospondyl amphibians known from the Triassic. Fossils belonging to this superfamily have been found in North America, Greenland, Europe, Asia, and Australia. The genus ''Ferganobatrachus'' f ...

, a clade of derived Triassic

stereospondyl The Stereospondyli are a group of extinct temnospondyl amphibians that existed primarily during the Mesozoic period. They are known from all seven continents and were common components of many Triassic ecosystems, likely filling a similar ecologi ...

s as the

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

to ''

Paracyclotosaurus crookshanki ''Paracyclotosaurus'' (meaning "Near Wheeled Lizard") is an extinct genus of temnospondyl amphibian, which would have appeared similar to today's salamander – but much larger, measuring up to long and weighing between . It lived in the Midd ...

'' from the Triassic Denwai Formation of

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

References

{{Taxonbar, from=Q16961664 Fossil taxa described in 2014 Triassic temnospondyls of Antarctica