''Cyclotosaurus'' 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 ...

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 ...

within the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Mastodonsauridae Mastodonsauridae is a family of capitosauroid temnospondyls. Fossils belonging to this family have been found in North America, Greenland, Europe, Asia, and Australia. The family Capitosauridae is synonymous with Mastodonsauridae. Description S ...

. It was of great size for an

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 ...

, had an elongated skull up to .

Etymology

The name means "round eared lizard" in

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...

, derived from round openings or fenestrae in the cheeks, which are thought to contain structures of the middle ear.

History

German naturalist

Eberhard Fraas Eberhard Fraas (26 June 1862 – 6 March 1915) was a German scientist, geologist and paleontologist. He worked as a curator at the Stuttgarter Naturaliensammlung and discovered the dinosaurs of the Tendaguru formation in then German East Afric ...

erected the genus ''Cyclotosaurus'' in 1889, with ''C. robustus'' (previously ''Mastodonsaurus robustus'') as 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 ...

. Several species are known, mainly from Germany and Poland in Central Europe, as well as East Greenland and Thailand. The relationships between species is unclear. ''"Labyrinthodon" pachygnathus'' Owen, 1842 and ''"L." leptognathus'' Owen, 1842 were transferred to ''Cyclotosaurus'', as ''C. pachygnathus'' and ''C. leptognathus'', by Paton (1974). However, Damiani (2001) assigned the two species to Mastodonsauroidea indeterminate and Stereospondyli indeterminate.

Palaeontology

The genus is known from the

Ladinian The Ladinian is a stage and age in the Middle Triassic series or epoch. It spans the time between Ma and ~237 Ma (million years ago). The Ladinian was preceded by the Anisian and succeeded by the Carnian (part of the Upper or Late Triassic). ...

in 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 ...

to the

Norian The Norian is a division of the Triassic Period. It has the rank of an age (geochronology) or stage (chronostratigraphy). It lasted from ~227 to million years ago. It was preceded by the Carnian and succeeded by the Rhaetian. Stratigraphic defi ...

in the

Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ...

, and represents the last of the Mastodonsaurids. Restoration of Cyclotosaurus by Szymon Górnicki

The oldest, questionable, species is ''Cyclotosaurus papilio'', known from a partial skull recovered from the Ladinian (Middle Triassic) age Upper

Muschelkalk The Muschelkalk (German for "shell-bearing limestone"; french: calcaire coquillier) is a sequence of sedimentary rock strata (a lithostratigraphic unit) in the geology of central and western Europe. It has a Middle Triassic (240 to 230 million ye ...

beds from

Baden-Württemberg Baden-Württemberg (; ), commonly shortened to BW or BaWü, is a German state () in Southwest Germany, east of the Rhine, which forms the southern part of Germany's western border with France. With more than 11.07 million inhabitants across a ...

in Germany. ''Cyclotosaurus robustus'' is known from the

Carnian The Carnian (less commonly, Karnian) is the lowermost stage of the Upper Triassic Series (or earliest age of the Late Triassic Epoch). It lasted from 237 to 227 million years ago (Ma). The Carnian is preceded by the Ladinian and is followed by t ...

(

)

Schilfsandstein Formation The Stuttgart Formation is a geologic formation in Germany. It preserves fossils dating back to the Carnian stage of the Triassic period.Stuttgart-Feuerbach Feuerbach is a borough (''Stadtbezirk'') of the city of Stuttgart. Its name is derived from the small river of the same name that flows from the neighboring district of Botnang through Feuerbach. Feuerbach is home to one of Germany's biggest indu ...

in Germany, while ''C. ebrachensis'' has been described from the Blasensandstein Formation in

Ebrach Ebrach is a municipality with market rights in the Upper Franconian district of Bamberg (district), Bamberg and the seat of the ''Municipal association, Verwaltungsgemeinschaft'' (municipal association) of Ebrach. Geography Ebrach lies between Ba ...

. ''Cyclotosaurus intermedius'' has been described from lacustrine deposits dated to the late

Krasiejów Krasiejów (german: Krascheow) is a village in the administrative district of Gmina Ozimek, within Opole County, Opole Voivodeship, in south-western Poland. It lies approximately east of Ozimek and east of the regional capital Opole. The villa ...

in southern Poland. It is so named as it has features intermediate between the more ancient ''C. robustus'' and more recent ''C. mordax''. Importantly, postcranial material of this species has been recovered, which is unusual this genus. ''Cyclotosaurus hemprichi'' is known from the

(Late Triassic) age Knollenmergel of Halberstadt, and ''Cyclotosaurus posthumus'' from the Stubensandstein (Norian) in Pfaffenhofen. A partial skull very similar to ''C. posthumus'' has been recovered from the Norian (Late Triassic) Huai Hin Lat Formation near

Chulabhorn Dam Chulabhorn Dam (เขื่อนจุฬาภรณ์) is a dam in Tambon Thung Lui Lai, Khon San District, Chaiyaphum Province, Thailand. It impounds the Phrom River, a tributary of the Mekong. The dam has diverted the Nam Phrong River. As ...

in Northeastern Thailand. In 2016 a new species, '' C. buechneri'', was described from the

(middle

) Stuttgart Formation of

Bielefeld Bielefeld () is a city in the Ostwestfalen-Lippe Region in the north-east of North Rhine-Westphalia, Germany. With a population of 341,755, it is also the most populous city in the administrative region (''Regierungsbezirk'') of Detmold and the ...

, the northernmost record in Germany. In 2017, ''Cyclotosaurus naraserluki'', a new endemic species from the Fleming Fjord Fm., East Greenland, was described as the closest ''Cyclotosaurus'' species to ''C. mordax'', also being the westernmost and northernmost known species of ''Cyclotosaurus''.Marzola, M., Mateus O., Shubin N. H., & Clemmensen L. B. (2017). Cyclotosaurus naraserluki, sp. nov., a new Late Triassic cyclotosaurid (Amphibia, Temnospondyli) from the Fleming Fjord Formation of the Jameson Land Basin (East Greenland). Journal of Vertebrate Paleontology. e1303501., 2017 In 2019 a ''Cyclotosaurus'' humerus was reported from a Rhaetian aged bone bed within Bonenburg clay pit in eastern

North Rhine-Westphalia North Rhine-Westphalia (german: Nordrhein-Westfalen, ; li, Noordrien-Wesfale ; nds, Noordrhien-Westfalen; ksh, Noodrhing-Wäßßfaale), commonly shortened to NRW (), is a States of Germany, state (''Land'') in Western Germany. With more tha ...

, Germany. This represents the only definitive non- brachyopoid Rhaetian temnospondyl, and the last known record of

Capitosauria Capitosauria is an extinct group of large temnospondyl amphibians with simplified stereospondyl vertebrae. Mainly living as piscivores in lakes and rivers, the Capitosauria and its sister taxon Trematosauria were the only major labyrinthodonts t ...

Phylogeny

The phylogeny of

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 ...

according to Witzmann ''et al.'' (2016). The phylogeny of the genus ''Cyclotosaurus'' according to Witzmann et al. (2016). See also alternative phylogenies from 2017 with the description of ''C. naraserluki.''

Ecology

''Cyclotosaurus'' are thought to have been semi-aquatic carnivores, though feeding strategies likely differed between species.

References

{{Taxonbar, from=Q2465083 Triassic temnospondyls of Europe Fossil taxa described in 1889 Prehistoric amphibian genera Taxa named by Eberhard Fraas