''Rotaurisaurus'' 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 ...

amphibian Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...

-grade

tetrapod Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids (pelycosaurs, extinct theraps ...

from the family

Lapillopsidae Lapillopsidae is a family of Temnospondyli Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order of small to giant tetrapods—often considered primitive amphibia ...

. This genus is known only from an incomplete crushed skull and associated left jaw, together given the designation UTGD (

University of Tasmania The University of Tasmania (UTAS) is a public research university, primarily located in Tasmania, Australia. Founded in 1890, it is Australia's fourth oldest university. Christ College, one of the university's residential colleges, first pro ...

Geological Department) 87795. The generic name, ''Rotaurisaurus'', is a combination of

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 ...

words translating to "circle-eared lizard". This references the shape of its

otic notch Otic notches are invaginations in the posterior margin of the skull roof, one behind each orbit. Otic notches are one of the features lost in the evolution of amniotes from their tetrapod ancestors. The notches have been interpreted as part of an ...

es, which acquire a circular form due to being partially enclosed by the tabular bones at the back of the skull. The specific name, ''contundo'', references the specimen's poor level of preservation, as it is derived from the Latin word for "squashed". The skull was discovered in 1960 at the Crisp and Gunn Quarry near

Hobart Hobart ( ; Nuennonne/Palawa kani: ''nipaluna'') is the capital and most populous city of the Australian island state of Tasmania. Home to almost half of all Tasmanians, it is the least-populated Australian state capital city, and second-small ...

Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ...

. This quarry contains rock layers from the Knocklofty Formation, which is dated to the early Triassic Period. For years this skull was believed to belong to a juvenile individual of '' Chomatobatrachus halei'', a species of lydekkerinid common in Tasmanian quarries. It was listed as such during John Cosgriff's 1974 review of Tasmanian temnospondyls. The ''Rotaurisaurus'' specimen was contained in a collapsed block of red siltstone which originally overlaid the grey siltstone of the formation's Poets Road Member. The Poets Road Member contained such fossils as a skeleton of the early

archosaur Archosauria () is a clade of diapsids, with birds and crocodilians as the only living representatives. Archosaurs are broadly classified as reptiles, in the cladistic sense of the term which includes birds. Extinct archosaurs include non-avian d ...

relative '' Tasmaniosaurus triassicus'', and is believed to hail between the Early

Induan The Induan is the first age of the Early Triassic epoch in the geologic timescale, or the lowest stage of the Lower Triassic series in chronostratigraphy. It spans the time between 251.902 Ma and Ma (million years ago). The Induan is sometimes ...

and Early

Olenekian In the geologic timescale, the Olenekian is an age in the Early Triassic epoch; in chronostratigraphy, it is a stage in the Lower Triassic series. It spans the time between Ma and Ma (million years ago). The Olenekian is sometimes divided into ...

ages of the early Triassic, about 250 million years ago. In 1999, Adam Yates established that the skull represented a new genus and species distinct from ''Chomatobatrachus''. He allied it with the enigmatic Australian temnospondyl ''

Lapillopsis ''Lapillopsis'' is an extinct genus of stereospondyl temnospondyl within the family Lapillopsidae. Fossils belonging to the genus have been found in the Arcadia Formation ( Rewan Group) of Queensland, Australia. History of study The type sp ...

'', and formulated a new family (Lapillopsidae) to contain the two genera. ''Rotaurisaurus'' possessed unusually shaped tabular bones, which typically formed triangular horn-like structures along the rear edge of the skull. In ''Rotaurisaurus'', these bones bent outwards to enclose the adjacent otic notches at the back of the head. Other unique features include the presence of a longitudinal ridge on the outer surface of each

quadratojugal bone The quadratojugal is a skull bone present in many vertebrates, including some living reptiles and amphibians. Anatomy and function In animals with a quadratojugal bone, it is typically found connected to the jugal (cheek) bone from the front and ...

(which was situated near the skull joint), and a raised rim of bone behind the

orbits In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

(eye holes).

References

Stereospondyls Paleontology in Tasmania {{temnospondyli-stub

See also

References