genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
temnospondyl
Temnospondyli (from Greek language, Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') or temnospondyls is a diverse ancient order (biology), order of small to giant tetrapods—often considered Labyrinth ...
within the
family
Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
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 ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...
, 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 classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...
, 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 Africa (n ...
erected the genus ''Cyclotosaurus'' in 1889, with ''C. robustus'' (previously ''Mastodonsaurus robustus'') as the
type species
In International_Code_of_Zoological_Nomenclature, 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 spe ...
. 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 epoch (geology), epochs of the Triassic period (geology), period or the middle of three series (stratigraphy), series in which the Triassic system (stratigraphy), system is di ...
to the
Norian
The Norian is a division of the Triassic geological period, Period. It has the rank of an age (geology), age (geochronology) or stage (stratigraphy), stage (chronostratigraphy). It lasted from ~227.3 to Mya (unit), million years ago. It was prec ...
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 a ...
, and represents the last of the mastodonsaurids.
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"; ) is a sequence of sedimentary rock, sedimentary rock strata (a lithostratigraphy, lithostratigraphic unit) in the geology of central and western Europe. It has a Middle Triassic (240 to 230 m ...
beds from
Baden-Württemberg
Baden-Württemberg ( ; ), commonly shortened to BW or BaWü, is a states of Germany, 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 i ...
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 227.3 ...
(
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 a ...
)
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 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
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 227.3 ...
in
Krasiejów
Krasiejów 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.
Paleontological localities ...
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
The Norian is a division of the Triassic geological period, Period. It has the rank of an age (geology), age (geochronology) or stage (stratigraphy), stage (chronostratigraphy). It lasted from ~227.3 to Mya (unit), million years ago. It was prec ...
(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 in Northeastern Thailand. In 2016 a new species, '' C. buechneri'', was described from 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 a ...
(middle
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 227.3 ...
)
Stuttgart Formation
The Stuttgart Formation is a geologic formation in Germany. It preserves fossils dating back to the Carnian stage of the Triassic period.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 () of Detmold (region), Detmold and the L ...
, 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 or North-Rhine/Westphalia, commonly shortened to NRW, is a States of Germany, state () in Old states of Germany, Western Germany. With more than 18 million inhabitants, it is the List of German states by population, most ...
, 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. '' Ferganobatrachus'' from the ...
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.