''Sclerocephalus'' is an extinct genus of

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 ...

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 ...

from the lowermost

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...

Germany Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...

and

Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...

with four valid species, including the type species ''S. haeuseri''. It is one of the most completely preserved and most abundant

Palaeozoic The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and '' ...

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 ...

s. ''Sclerocephalus'' was once thought to be closely related to eryopoid temnospondyls, but it is now thought to be more closely related to archegosauroids. It is the only genus in the family Sclerocephalidae.

Description and lifestyle

The adults animals reached a body length of ca. 150 cm, and had an elongate trunk and a laterally compressed tail. In some specimens lateral line sulci are retained. These body features suggest an aquatic mode of life, with aquatic larvae that probably breathed with external gills like modern tadpoles, while the adults breathed with lungs. ''Sclerocephalus'' underwent significant changes during its

ontogeny Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the stu ...

, for example the eyes are much larger and the tail much longer in larvae than in adults. The latest revision, redescription and phylogenetic study of this genus was provided by Schoch & Witzmann (2009). ''Sclerocephalus'' was often classified within the deprecated paraphyletic taxa

Stegocephalia Stegocephali (often spelled Stegocephalia) is a group containing all four-limbed vertebrates. It is equivalent to a broad definition of Tetrapoda: under this broad definition, the term "tetrapod" applies to any animal descended from the first ve ...

and

Labyrinthodontia "Labyrinthodontia" (Greek, 'maze-toothed') is an informal grouping of extinct predatory amphibians which were major components of ecosystems in the late Paleozoic and early Mesozoic eras (about 390 to 150 million years ago). Traditionally consid ...

, because of a skull that was connected to the shoulder girdle and teeth of labyrinthodont type. The skull had a distinct

pineal foramen A parietal eye, also known as a third eye or pineal eye, is a part of the epithalamus present in some vertebrates. The eye is located at the top of the head, is photoreceptive and is associated with the pineal gland, regulating circadian rhyth ...

. Besides the usual row of teeth in the upper and lower jaw, ''Sclerocephalus'' also had three additional pairs of palatine teeth. From specimens with fossilized stomach content we know the adults mainly fed on fish of the genus ''

Paramblypterus ''Paramblypterus'' is an extinct genus of bony fish. This taxon would often fall under predation from Paleozoic tetrapods such as '' Sclerocephalus'' See also * Prehistoric fish * List of prehistoric bony fish A ''list'' is any set of ite ...

'', but sometimes also on other amphibians ('' Branchiosaurus'', ''

Micromelerpeton ''Micromelerpeton'' is an extinct genus of dissorophoidean euskelian temnospondyl 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 re ...

'') and even small conspecifics.

Discovery

The holotype of ''Sclerocephalus haeuseri'' was described 1847 by the German paleontologist

Georg August Goldfuss Georg August Goldfuss (Goldfuß, 18 April 1782 – 2 October 1848) was a German palaeontologist, zoologist and botanist. Goldfuss was born at Thurnau near Bayreuth. He was educated at Erlangen, where he graduated PhD in 1804 and became profes ...

, who misidentified the fossil as skull of a fish. The famous American vertebrate paleontologist

Alfred Romer Alfred Sherwood Romer (December 28, 1894 – November 5, 1973) was an American paleontologist and biologist and a specialist in vertebrate evolution. Biography Alfred Romer was born in White Plains, New York, the son of Harry Houston Romer an ...

recognized in 1939 that the fossil amphibians described as ''Leptorophus levis'' are the larvae of ''Sclerocephalus''. The most important modern research on ''Sclerocephalus'' was published by Boy (1988) and Schoch (2000, 2002, 2003, 2009). A famous locality that yielded numerous excellently preserved fossils of ''Sclerocephalus'' is

Odernheim am Glan Odernheim am Glan is an ''Ortsgemeinde'' – a municipality belonging to a ''Verbandsgemeinde'', a kind of collective municipality – in the Bad Kreuznach district in Rhineland-Palatinate, Germany. It belongs to the ''Verbandsgemeinde'' of Bad ...

Rhineland-Palatinate Rhineland-Palatinate ( , ; german: link=no, Rheinland-Pfalz ; lb, Rheinland-Pfalz ; pfl, Rhoilond-Palz) is a western state of Germany. It covers and has about 4.05 million residents. It is the ninth largest and sixth most populous of the ...

(Germany), where the Permian sediments of the

Rotliegend The Rotliegend, Rotliegend Group or Rotliegendes (german: the underlying red) is a lithostratigraphy, lithostratigraphic unit (a sequence of rock strata) of latest Carboniferous to Guadalupian (middle Permian) age that is found in the subsurface of ...

have even been named "Stegocephalenkalke" (= Stegocephalia limestones).

Taxonomy

Krätschmer (2004) questioned the validity of the type species ''Sclerocephalus haeuseri'', of which the

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 ...

is lost, and considered ''Pfarrwaldia jeckenbachensis'' as valid name for the

neotype In biology, a type is a particular specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally attached. In other words, a type is an example that serves to anchor or centralizes the ...

designated by Boy (1988). This was refuted in the revision of Schoch & Witzmann (2009), who considered ''P. jeckenbachensis'' as younger

synonym A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

of ''S. haeuseri''. The following four species are recognized as valid by Schoch & Witzmann (2009): *''Sclerocephalus haeuseri'' Goldfuss, 1847 from the

Asselian In the geologic timescale, the Asselian is the earliest geochronologic age or lowermost chronostratigraphic stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Asselian lasted between and million years ago (Ma) ...

(Lower

) of

in Germany. *''Sclerocephalus bavaricus'' (Branco, 1887) from the

(Lower Rotliegend) or uppermost Pennsylvanian (

Gzhelian The Gzhelian ( ) is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the youngest stage of the Pennsylvanian, the youngest subsystem of the Carboniferous. The Gzhelian lasted from to Ma. It follows the Kasim ...

) of Rhineland-Palatinate in Germany. *''Sclerocephalus jogischneideri'' Werneburg, 1992 from the

(Lower Rotliegend) of

Thuringia Thuringia (; german: Thüringen ), officially the Free State of Thuringia ( ), is a state of central Germany, covering , the sixth smallest of the sixteen German states. It has a population of about 2.1 million. Erfurt is the capital and larg ...

in Germany *''Sclerocephalus nobilis'' (Krätschmer & Resch, 2005) from the

(Lower Rotliegend) of Rhineland-Palatinate in Germany.

Phylogeny

The phylogenetic relationships of ''Sclerocephalus'' are uncertain. It was traditionally considered a close relative of the genus ''

Onchiodon ''Onchiodon'' is an extinct genus of temnospondyl. It is primarily known from the Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million yea ...

'', and both were placed in the family

Actinodontidae Eryopidae were a group of medium to large amphibious temnospondyli, known from North America and Europe. They are defined as all eryopoids with interpterygoid vacuities (spaces in the interpterygoid bone) that are rounded at the front; and larg ...

. Actinodontidae was thought to be closely related to the family

Eryopidae Eryopidae were a group of medium to large amphibious temnospondyli, known from North America and Europe. They are defined as all eryopoids with interpterygoid vacuities (spaces in the interpterygoid bone) that are rounded at the front; and larg ...

, and is now considered a synonym of that group. However, while ''Sclerocephalus'' shares some similarities with eryopids, it also shares much in common with a group of large-bodied, semiaquatic temnospondyls called Stereospondylomorpha. ''Sclerocephalus'' and ''Onchiodon'' are no longer thought to be closely related, and while ''Onchiodon'' remains a close relative of eryopids, ''Sclerocephalus'' is often grouped near the genus ''

Archegosaurus ''Archegosaurus'' is a genus of temnospondyl amphibian which lived during the Asselian to Wuchiapingian stages of the Permian, around 299-253 million years ago. The remains of this animal, consisting of at least 90 partial skeletons (mostly sk ...

'' as a basal stereospondylomorph. The most commonly accepted phylogeny of temnospondyls (first proposed by Yates and Warren

000 Triple zero, Triple Zero, Zero Zero Zero, Triple 0, Triple-0, 000, or 0-0-0 may refer to: * 000 (emergency telephone number), the Australian emergency telephone number * "Triple Zero", a song by AFI (band), AFI from ''Shut Your Mouth and Open Your ...

divides the group into two different branches called Limnarchia and

Euskelia Euskelia is a clade of extinct Temnospondyl amphibians. ''Euskelia'' is a stem-based taxon including all temnospondyls more closely related to ''Eryops'' than to ''Parotosuchus ''Parotosuchus'' is an extinct genus of capitosaurian temnospondyl ...

. Limnarchia is a diverse Mesozoic clade that includes Stereospondylomorpha. Euskelia is a smaller Paleozoic clade that includes Eryopidae and the group

Dissorophoidea Dissorophoideans are a clade of medium-sized, temnospondyl amphibians that appeared during the Moscovian in Euramerica, and continued through to the Late Permian and the Early Triassic of Gondwana. They are distinguished by various details of the ...

, which may have given rise to modern amphibians. An earlier phylogeny proposed by Boy (1990) takes a different view, combining Eryopidae and Stereospondylomorpha into the group

Eryopoidea Eryopoidea are a taxon of late Carboniferous and Permian temnospondyli amphibians, known from North America and Europe. Carroll includes no fewer than ten families, but Yates and Warren replace this with a cladistic approach and include three fa ...

, with dissorophoids as distant relatives. If this phylogeny is correct, ''Sclerocephalus'' would be a basal member of Eryopoidea, close to the ancestry of most other stereospondylomorphs. Schoch & Witzmann (2009) found support for the Eryopoidea clade. They included ''Sclerocephalus'' in their phylogenetic analysis and found it to nest at the base of Stereospondylomorpha. Below is a

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...

from their study:

Notes

References

*Goldfuss, A. 1847: ''Beiträge zur vorweltlichen Fauna des Steinkohlegebirges''. Naturhistorischer Verein der Preussischen Rheinlande, Bonn. *Boy, J.A. 1988: Über einige Vertreter der Eryopoidea (Amphibia: Temnospondyli) aus dem europäischen Rotliegenden (höchstes Karbon-Perm). 1. ''Sclerocephalus''. ''Paläontologische Zeitschrift'', 62: 107-13
Fulltext
*Krätschmer, K. 2004: Revision von 'Sclerocephalus haeuseri' (Goldfuss) 1847 (Stem-Stereospondyli). ''Geowissenschafftliche Beiträge zum Saarpfälzischen Rotliegenden'', 2: 1-52. *Krätschmer, K. & Resch, M. 2005: ''Klauswaldia nobile'' gen et. spec. nov. Ein außergewöhnlicher stereospondyler Stegocephale aus dem Rotliegend (Unter-Perm) von Odernheim (Rheinland-Pfalz, SW-Deutschland). ''Geowissenschafftliche Beiträge zum Saarpfälzischen Rotliegenden'', 3: 39-65. *Romer, A.S. 1947: Review of the Labyrinthodontia. ''Bull. Mus. Compar. Zool.'', 99: 1-368. *Schoch, R.R. 2002. The stapes and middle ear of the Permo-Carboniferous tetrapod Sclerocephalus. ''Neues Jahrbuch Geologie Paläontologie Monatshefte'', 2002: 671-680. *Schoch, R.R. 2003. The early larval ontogeny of the Permo-Carboniferous temnospondyl ''Sclerocephalus''. ''Palaeontology'', 46: 1055-107
Abstract
*Schoch, R.R. & Millner, A.R. 2000. Sterospondyli. p. 203 in: Wellnhofer, P. (ed.): ''Handbuch der Paläoherpetologie'', vol. 3B. Pfeil, Munich. *Schoch, R.R. & Witzmann, F. 2009: Osteology and relationships of the temnospondyl genus ''Sclerocephalus''. ''Zoological Journal of the Linnean Society'', 157(1): 135–16
Abstract
*Werneburg, R. 1992: ''Sclerocephalus jogischneideri'' n. sp. (Eryopoidea, Amphibia) aus dem Unterrotliegenden (Unterperm) des Thüringer Waldes. ''Freiberger Forschungshefte C'', 45: 29-48. *Werneburg, R. & Steyer, J.S. 1999: Redescription of the holotype of ''Actinodon frossardi'' (Amphibia, Temnospondyli) from the Lower Permian of the Autun basin (France). ''Geobios'', 32(4): 599-60
Abstract
{{Taxonbar, from=Q2290216 Fossils of Germany Carboniferous temnospondyls of Europe Permian temnospondyls of Europe Stereospondylomorphs Fossil taxa described in 1847 Prehistoric amphibian genera Taxa named by Georg August Goldfuss