''Cyclotosaurus'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

temnospondyl Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') is a diverse order of small to giant tetrapods—often considered primitive amphibians—that flourished worldwide during the Carbo ...

within the

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

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. Descripti ...

. It was of great size for an amphibian, 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 p ...

, 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 Afri ...

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 specime ...

. 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 in the

Late Triassic The Late Triassic is the third and final epoch of the Triassic Period in the geologic time scale, spanning the time between Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch and followed by the Early Jurassic 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, sedimentary rock strata (a lithostratigraphy, lithostratigraphic unit) in the geology of central and western Europe. It has a Mid ...

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 (stratigraphy), stage of the Upper Triassic series (stratigraphy), Series (or earliest age (geology), age of the Late Triassic Epoch (reference date), Epoch). It lasted from 237 to 227 m ...

(

) Schilfsandstein Formation in Stuttgart-Feuerbach in Germany, while ''C. ebrachensis'' has been described from the Blasensandstein Formation in Ebrach. ''Cyclotosaurus intermedius'' has been described from lacustrine deposits dated to the late

in Krasiejów 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 Norian (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 state (''Land'') in Western Germany. With more than 18 million inha ...

, 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 ...

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'' ...

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