''Sclerocephalus'' is an extinct genus 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 ...

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 ...

from the lowermost

Permian The Permian ( ) is a geologic period and System (stratigraphy), 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 251.902 Mya. It is the s ...

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

and

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

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 first of three geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma at the start of ...

tetrapod A tetrapod (; from Ancient Greek :wiktionary:τετρα-#Ancient Greek, τετρα- ''(tetra-)'' 'four' and :wiktionary:πούς#Ancient Greek, πούς ''(poús)'' 'foot') is any four-Limb (anatomy), limbed vertebrate animal of the clade Tetr ...

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 ovum, egg to adult. The term can also be used to refer to t ...

, 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, from Greek , lit. "roofed head") is a clade of vertebrate animals containing all fully limbed tetrapodomorphs. It is equivalent to a broad definition of the superclass Tetrapoda: under this broad ...

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 conside ...

, 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 (third eye, pineal eye) is a part of the epithalamus in some vertebrates. The eye is at the top of the head; is photoreceptive; and is associated with the pineal gland, which regulates circadian rhythmicity and hormone production ...

. 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 Paleozoic bony fish. This taxon would often fall under predation from Paleozoic tetrapods such as '' Sclerocephalus'' See also * Prehistoric fish * List of prehistoric bony fish This list of prehis ...

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

Branchiosaurus ''Branchiosaurus'' (from , 'gill' and , 'lizard') is a genus of small, prehistoric amphibians. Fossils have been discovered in strata dating from the late Pennsylvanian Epoch to the Permian Period. The taxa may be invalid; the material refe ...

'', ''

Micromelerpeton ''Micromelerpeton'' is an extinct genus of dissorophoidean temnospondyl within the family Micromelerpetontidae Micromelerpetontidae (also spelled Micromelerpetidae) is an extinct family of dissorophoid temnospondyls that lived from the Late Ca ...

'') and even small conspecifics.

Discovery

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

Georg August Goldfuss Georg August Goldfuß (18 April 1782 – 2 October 1848) was a German palaeontologist, zoologist and botanist. He became a professor of zoology at the University of Erlangen and later at the University of Bonn. He coined the terms "protozoa" an ...

, 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 (Germany), Ortsgemeinde'' – a Municipalities of Germany, municipality belonging to a ''Verbandsgemeinde'', a kind of collective municipality – in the Bad Kreuznach (district), Bad Kreuznach Districts of ...

Rhineland-Palatinate Rhineland-Palatinate ( , ; ; ; ) 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 sixteen states. Mainz is the capital and largest city. Other cities are ...

(Germany), where the Permian sediments of the

Rotliegend The Rotliegend, Rotliegend Group or Rotliegendes () is a lithostratigraphic unit (a sequence of rock strata) of latest Carboniferous to Guadalupian (middle Permian) age that is found in the subsurface of large areas in western and central Europe ...

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 (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

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 associated. In other words, a type is an example that serves to anchor or centralizes ...

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 precisely 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 a ...

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 Pennsylvanian may refer to: * A person or thing from Pennsylvania * Pennsylvanian (geology) The Pennsylvanian ( , also known as Upper Carboniferous or Late Carboniferous) is, on the International Commission on Stratigraphy, ICS geologic timesc ...

(

Gzhelian The Gzhelian ( ) is an age in the ICS geologic time scale 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 Ka ...

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

(Lower Rotliegend) of

Thuringia Thuringia (; officially the Free State of Thuringia, ) is one of Germany, Germany's 16 States of Germany, states. With 2.1 million people, it is 12th-largest by population, and with 16,171 square kilometers, it is 11th-largest in area. Er ...

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 and Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the ...

'', and both were placed in the family

Actinodontidae Actinodontidae is an extinct family of temnospondyls Temnospondyli (from Greek τέμνειν, ''temnein'' 'to cut' and σπόνδυλος, ''spondylos'' 'vertebra') or temnospondyls is a diverse ancient order of small to giant tetrapods—of ...

. Actinodontidae was thought to be closely related to the family

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

, 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 Stereospondylomorpha is a clade of temnospondyls. It includes the superfamily Archegosauroidea and the more diverse group Stereospondyli. Stereospondylomorpha was first proposed by Yates and Warren (2000), who found Archegosauroidea and Stereosp ...

. ''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 skull ...

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

000 Triple zero, Zero Zero Zero, 0-0-0 or variants may refer to: * 000 (emergency telephone number), the Australian emergency telephone number * 000, the size of several small List of screw drives, screw drives * 0-0-0, a Droid (Star Wars)#0-0-0, dro ...

divides the group into two different branches called

Limnarchia Limnarchia is a clade of temnospondyls. It includes the mostly Carboniferous-Permian age Dvinosauria and the mostly Permian-Triassic age Stereospondylomorpha. The clade was named in a 2000 phylogenetic analysis of stereospondyls and their relativ ...

and

Euskelia Euskelia is a proposed clade of extinct temnospondyl amphibians. The naming derives from the ancient Greek ''eu'', meaning "true", and ''skelos'', meaning "limb", in reference to well-ossified limb bones with crests to which muscles were attached ...

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

Dissorophoidea Dissorophoidea is 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 is a clade of Pennsylvanian (geology), late Carboniferous and Permian temnospondyli, temnospondyl amphibians, known from North America and Europe. Carroll (1998) includes no fewer than ten families, but Yates and Warren (2000) replaced ...

, 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

. Below is a

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

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 Stereospondylomorpha Fossil taxa described in 1847 Prehistoric amphibian genera Taxa named by Georg August Goldfuss