Dissorophidae is an extinct

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 ...

of medium-sized,

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 ...

amphibians that flourished during the late

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 years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...

and early

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 ...

periods. The clade is known almost exclusively from North America.

History of study

Dissorophidae is a diverse clade that was named in 1902 by George A. Boulenger. Junior synonyms include Otocoelidae, Stegopidae, and Aspidosauridae. Early in the study of dissorophoids when the relationships of different taxa were not well-resolved and most taxa had not been described, Dissorophidae sometimes came to include taxa that are now not regarded as dissorophids and may have excluded earlier described taxa that are now regarded as dissorophids. Amphibamiforms were widely regarded as small-bodied dissorophids, and at one point, Dissorophidae was also suggested to also include

Trematopidae Trematopidae is a family of dissorophoid temnospondyl spanning the late Carboniferous to the early Permian. Together with Dissorophidae, the family forms Olsoniformes, a clade comprising the medium-large terrestrial dissorophoids. Trematopids a ...

19th century

In 1895, American paleontologist Edward Drinker Cope named ''

Dissorophus ''Dissorophus'' (DI-soh-ROH-fus) (meaning "double roof" for two layers of armor) is an extinct genus of temnospondyl amphibian that lived during the Early Permian Period about 273 million years ago. Its fossils have been found in Texas and in Ok ...

'' from the early Permian of Texas. This was the first dissorophid to be described as such, although ''

Parioxys ''Parioxys'' is an extinct genus of temnospondyl amphibian from the Early Permian of Texas. History of study The type species, ''Parioxys ferricolus'', was named in 1878 by American paleontologist Edward Drinker Cope based on two badly preserv ...

'', named by Cope in 1878, and ''Zygosaurus'', named by the Russian paleontologist Karl von Eichwald in 1848, have also been regarded as dissorophids. A second species of ''Dissorophus'' as well as both species of the genus ''Otocoelus'' that were all named in 1896 by Cope in two papers are now regarded as junior synonyms of the type species of ''Dissorophus'', ''D. multicinctus''.

20th century

The early 20th century saw a large expansion in the study of dissorophids. In 1904, German paleontologist

Ferdinand Broili Ferdinand Broili (11 April 1874 in Mühlbach – 30 April 1946 in Mühlbach) was a German paleontologist. He studied natural sciences at the universities of Würzburg and Munich, where his influences were Karl von Zittel and August Rothpletz. ...

named the first species of ''

Aspidosaurus ''Aspidosaurus'' is an extinct genus of dissorophoid temnospondyl within the family Dissorophidae. Description Like other dissorophids, ''Aspidosaurus'' species had a single row of plates formed by expansions of the neural spines.

, A. chiton'', from the early Permian of Texas. Additional species of ''Aspidosaurus'' were named shortly thereafter, including ''Aspidosaurus glascocki'' from the early Permian of Texas and ''Aspidosaurus novomexicanus'' from the late Carboniferous of New Mexico. A third species, "''Aspidosaurus crucifer''" described by American paleontologist E.C. Case is now regarded as an indeterminate aspidosaurine. In 1910, two of the best-known dissorophid genera were named: ''

Cacops aspidephorus ''Cacops'' ("ugly look" for its strange appearance), is a genus of dissorophid temnospondyls from the Kungurian stage of the early Permian of the United States. ''Cacops'' is one of the few olsoniforms (dissorophids and the larger trematopids) ...

'' and ''

Platyhystrix ''Platyhystrix'' (from el, πλατύς , 'flat' and el, ῠ̔́στρῐξ , 'porcupine') was a temnospondyl amphibian with a distinctive sail along its back, similar to the unrelated synapsids, ''Dimetrodon'' and ''Edaphosaurus''. It lived du ...

'' (as a species of '' Ctenosaurus''; proper name erected in 1911). Case also provided new information on ''Dissorophus'' in 1910''.'' In 1911, Case named ''Alegeinosaurus aphthitos'' from the early Permian of Texas. In 1914, Samuel W. Williston described the first species of ''

Broiliellus ''Broiliellus'' is an extinct genus of dissorophoid temnospondyl within the family Dissorophidae. ''Broiliellus'' is most closely related to the genus ''Dissorophus'', and both have been placed in the subfamily Dissorophinae. ''Broiliellus'' is ...

'', ''B. texensis''. Additional information on ''Parioxys ferricolus'' was provided in two studies by Egyptian paleontologist Y.S. Moustafa in 1955. The 1960s were a particular productive time for dissorophid research. In two separate papers published in 1964, Canadian paleontologist

Robert L. Carroll Robert "Bob" Lynn Carroll (May 5, 1938 – April 8, 2020) was an American–Canadian vertebrate paleontologist who specialised in Paleozoic and Mesozoic amphibians and reptiles. Biography Carroll was an only child and grew up on a farm ne ...

named four new taxa: '' Brevidorsum profundum, Broiliellus brevis'', and '' Parioxys bolli'' from the early Permian of Texas and ''

Conjunctio multidens ''Conjunctio'' is an extinct genus of dissorophid temnospondyl amphibian from the early Permian of New Mexico. The type species, ''Conjunctio multidens'', was named by paleontologist Robert L. Carroll in 1964. History of study The holotype s ...

'' from the early Permian of New Mexico. Conjunctio was named from a specimen originally referred to ''Aspidosaurus novomexicanus'' by Case et al. (1913) that was also placed in ''Broiliellus'' by American paleontologist

Wann Langston Wann Langston Jr. (1921 – April 7, 2013) was an American paleontologist and professor at the University of Texas at Austin. Langston worked on a number of different reptiles and amphibians in his long career, beginning with the 1950 description ...

in 1953 before being divided again by Carroll. In 1965, American paleontologist E.C. Olson described the first and only middle Permian dissorophid from North America, '' Fayella chickashaensis'', on the basis of an isolated braincase and isolated fragments. A large postcranial skeleton from a different locality was referred to this taxon by Olson in 1972. In 1966, American paleontologist Robert E. DeMar named a new taxon, "''Longiscitula houghae''" from the early Permian of Texas; this is now regarded as a junior synonym of ''Dissorophus multicinctus'' by British paleontologist Andrew Milner. DeMar also provided the first synthesis of the morphological diversity and possible function of dissorophid osteoderms in 1966 and named two new species of ''Broiliellus'' in 1967, ''B. arroyoensis'' and ''B. olsoni'', and completed a detailed revision of ''D. multicinctus'' in 1968. In 1971, American paleontologist Peter Vaughn described one of the few dissorophids outside of New Mexico, Texas, and Oklahoma, '' Astreptorhachis ohioensis'' from the late Carboniferous of Ohio, represented by a series of fused neural spines and osteoderms. American paleontologist John Bolt published a survey of dissorophid osteoderms in 1974 with an emphasis on taxonomic utility and differentiation and reports of material from the early Permian Richards Spur locality in Oklahoma; in 1977, Bolt reported ''Cacops'' from the locality. In 1980, Russian paleontologist Yuri Gubin described two new middle Permian dissorophids from Russia: '' Iratusaurus vorax'' and '' Kamacops acervalis''. The most complete cranial material of ''Platyhystrix rugosus'' was described in 1981 by a team led by American paleontologist David Berman. Additional postcranial material of ''Platyhystrix'', primarily the characteristic hyperelongate spines, was also periodically reported. The revision of ''

Ecolsonia cutlerensis ''Ecolsonia'' is an extinct genus of trematopid temnospondyl. Its phylogenetic position within Olsoniformes has been historically debated, but it is presently considered to be a trematopid. History of study The holotype of ''Ecolsonia'' is a ...

'' in 1985 by Berman and colleagues placed the taxon as a dissorophid, but this taxon is more often recovered as a trematopid. In 1999, Chinese paleontologists Li Jinling and Cheng Zhengwu described the first and only dissorophid from eastern Asia, the middle Permian '' Anakamacops petrolicus'' from China.

21st century

In 2003, American paleontologists Berman and Spencer G. Lucas named a new species of ''Aspidosaurus'' from Texas, ''A. binasser''. Two papers on the osteoderm biomechanics of ''Cacops aspidephorus'' and ''Dissorophus multicinctus,'' led by Canadian paleontologist David Dilkes, were published in 2007 and 2009. In 2009, a team led by Canadian paleontologist

Robert Reisz Robert Rafael Reisz is a Canadian paleontologist and specialist in the study of early amniote and tetrapod evolution. Research career Reisz received his B.Sc. (1969), M.Sc. (1971) and Ph.D. (1975) from McGill University as Robert L. Carrol ...

described a new species of ''Cacops, C. morrisi'', from the Richards Spur locality; additional material of this taxon was described in 2018 by American paleontologist Bryan M. Gee and Reisz. A second species from the locality was described in 2012 by German paleontologist Nadia B. Fröbisch and Reisz, ''C. woehri''; additional material of ''Cacops woehri'' was described in 2015 by a team led by Fröbisch. A team led by German paleontologist Florian Witzmann published a comparative histology study that sampled a number of dissorophids in 2010. May et al. (2011) described material of ''Aspidosaurus'' from the late Carboniferous of the mid-continent of North America. The first phylogenetic review of the Dissorophidae was published in 2012 by Schoch. In 2013, three new dissorophids were named in a festschrift dedicated to Reisz in Comptes Rendus Palévol: ''Broiliellus reiszi'' from the early Permian of New Mexico in a study led by Canadian paleontologist Robert Holmes; ''

Scapanops neglecta ''Scapanops'' is an extinct genus of dissorophid temnospondyl amphibian known from the Early Permian Nocona Formation of north-central Texas, United States. It contains only the type species ''Scapanops neglecta'', which was named by Rainer R. ...

'' from the early Permian of Texas in a study by German paleontologists Schoch and Hans-Dieter Sues, re-evaluating a specimen historically referred to as the Admiral Taxon; and '' Reiszerpeton renascentis'' from the early Permian of Texas in a review of material referred to the amphibamiform '' Tersomius texensis'' by a team led by Canadian paleontologist Hillary C. Maddin. In 2018, Chinese paleontologist Liu Jun provided an updated osteology of ''Anakamacops'' based on substantially more complete material and erected the tribe Kamacopini to group the middle Permian dissorophids from Eurasia. Two separate studies led by Gee were also published that year, one reappraising the early Permian ''Alegeinosaurus aphthitos'' from Texas, which he suggested to be a junior synonym of ''Aspidosaurus'', and another reappraising the middle Permian ''Fayella chickashaensis'' from Oklahoma, in which the authors determined that the holotype was a nomen dubium but that the referred specimen was sufficiently distinct to warrant erecting a new taxon, ''Nooxobeia gracilis''. Also in 2018, Gee and Reisz reported postcrania of a large indeterminate dissorophid from Richards Spur, which was followed by another study the following year by a team led by Gee that reported extensive new material from several dissorophids from Richards Spur, including the first documentation of ''Aspidosaurus'' and ''Dissorophus'' from the locality.

Anatomy

Dissorophids are most readily recognized for their distinctive osteoderms, although these are not unique to either dissorophids among temnospondyls or to temnospondyls among early tetrapods. It is also debated whether ''Platyhystrix'' has true osteoderms or simply ornamented neural spines with similar morphology to the ornamentation of osteoderms in other taxa. There is also great variability in the osteoderms, both in the number of series and in the overall proportions and anatomy. Dissorophines like ''Dissorophus'' typically possess wide osteoderms in contrast to eucacopines like ''Cacops''. Both groups have two series of osteoderms that are relatively flat, in contrast to aspidosaurines, which purportedly a single series that is dorsally keeled to form an inverted-V morphology; it has been suggested, based on CT data, that at least some aspidosaurines may actually have two series of osteoderms but that one is largely obscured. Although osteoderm morphology has been shown to not exert a discernible influence on dissorophid phylogeny, osteoderms remain a major hallmark used to differentiate major clades within Dissorophidae and remain useful for establishing the monophyly of the group within Dissorophoidea. Schoch & Milner (2014) list several features that diagnose dissorophids, but most of these are only useful for differentiating the clade from the closely related trematopids, and some are outdated in light of newer research: (1) maxillary tooth row terminating at or anterior to the posterior orbital margin; (2) basipterygoid region firmly sutured; (3) no prefrontal-postfrontal contact; (4) absence of denticles on the basal plate of the parasphenoid; (5) no pterygoid-vomer contact; (6) short postorbital; (7) long and parallel-sided choana; and (8) absence of a supinator process. Aspidosaurines and platyhystricines are represented largely by postcranial material, and thus features such as osteoderms are some of the only differentiators for these taxa, but dissorophines and eucacopiens also have many cranial differences, such as the relative proportions of the skull. Most dissorophids are medium-sized, being intermediate between the small amphibamiforms and the larger trematopids, but Dissorophidae includes the largest known dissorophoids, all from the middle Permian of Eurasia, with skull lengths exceeding 30 cm.

Fossil range

Below is a timeline of the known fossil ranges of dissorophids. ImageSize = width:700px height:auto barincrement:15px PlotArea = left:10px bottom:50px top:10px right:10px Period = from:-310 till:-251 TimeAxis = orientation:horizontal ScaleMajor = unit:year increment:10 start:-310 ScaleMinor = unit:year increment:5 start:-310 TimeAxis = orientation:hor AlignBars = justify Colors = #legends id:CAR value:claret id:ANK value:rgb(0.4,0.3,0.196) id:HER value:teal id:HAD value:green id:OMN value:blue id:black value:black id:white value:white id:paleozoic value:rgb(0.6,0.75,0.55) id:carboniferous value:rgb(0.4,0.65,0.6) id:permian value:rgb(0.94,0.25,0.24) BarData= bar:eratop bar:space bar:periodtop bar:space bar:NAM1 bar:NAM2 bar:NAM3 bar:NAM4 bar:NAM5 bar:NAM6 bar:NAM7 bar:NAM8 bar:NAM9 bar:NAM10 bar:NAM11 bar:NAM12 bar:NAM13 bar:NAM14 bar:NAM15 bar:NAM16 bar:NAM17 bar:NAM18 bar:NAM19 bar:NAM20 bar:NAM21 bar:NAM22 bar:NAM23 bar:NAM24 bar:space bar:period bar:space bar:era PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25 shift:(7,-4) bar:periodtop from: -310 till: -299 color:carboniferous text:

from: -299 till: -251 color:permian text:

bar:eratop from: -310 till: -251 color:paleozoic text:

Paleozoic Era 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 ' ...

PlotData= align:left fontsize:M mark:(line,white) width:5 anchor:till align:left color:carboniferous bar:NAM1 from:-308 till:-303.9 text: Astreptorhachis ohioensis color:carboniferous bar:NAM2 from:-302.3 till:-302 text: cf. Platyhystrix color:carboniferous bar:NAM3 from:-301 till:-300.7 text: cf. Aspidosaurus color:carboniferous bar:NAM4 from:-301 till:-297.5 text: Platyhystrix rugosus color:carboniferous bar:NAM5 from:-300 till:-298 text: Aspidosaurus novomexicanus color:permian bar:NAM6 from:-294.6 till:-277 text: Aspidosaurus sp. color:permian bar:NAM7 from:-294 till:-290.7 text: Brevidorsum profundum color:permian bar:NAM8 from:-293 till:-278.5 text:

color:permian bar:NAM9 from:-290.3 till:-284.7 text: Broiliellus brevis color:permian bar:NAM10 from:-290.3 till:-284.7 text: Dissorophus angustus color:permian bar:NAM11 from:-278.7 till:-277.2 text: Conjunctio sp. color:permian bar:NAM12 from:-277.1 till:-275.9 text: Broiliellus texensis color:permian bar:NAM13 from:-274 till:-272.5 text: Aspidosaurus chiton color:permian bar:NAM14 from:-274 till:-272.5 text: Aspidosaurus binasser color:permian bar:NAM15 from:-274 till:-272.5 text: Broiliellus arroyoensis color:permian bar:NAM16 from:-274 till:-272.5 text: Dissorophus multicinctus color:permian bar:NAM17 from:-274 till:-271 text:

Cacops morrisi ''Cacops'' ("ugly look" for its strange appearance), is a genus of dissorophid temnospondyls from the Kungurian stage of the early Permian of the United States. ''Cacops'' is one of the few olsoniforms (dissorophids and the larger trematopids ...

color:permian bar:NAM18 from:-272.5 till:-270.9 text:

color:permian bar:NAM19 from:-270.9 till:-269.9 text: Nooxobeia gracilis color:permian bar:NAM20 from:-269.8 till:-268 text: Anakamacops petrolicus color:permian bar:NAM21 from:-269.8 till:-268 text: Iratusaurus vorax color:permian bar:NAM22 from:-269.8 till:-268 text: Kamacops acervalis color:permian bar:NAM23 from:-269.8 till:-268 text: Zygosaurus lucius PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25 bar:period from: -310 till: -299 color:carboniferous text:

from: -299 till: -251 color:permian text:

bar:era from: -310 till: -251 color:paleozoic text:

Relationships

Four subfamilies comprise the various dissorophids. Eucacopine (sensu Schoch & Sues, 2013) was traditionally referred to as Cacopinae and includes ''Cacops'' and the middle Permian Eurasian taxa (''Anakamacops, Iratusaurus, Kamacops, Zygosaurus''). Dissorophinae includes ''Dissorophus'' and all four species of ''Broiliellus''. These are the two most widely utilized distinctions within Dissorophidae, although Aspidosaurinae (which includes only ''Aspidosaurus'' and indeterminate ''Aspidosaurus''-like material) was recently revived along with the erection of the new Platyhystricinae (''Platyhystrix'' and ''Astreptorhachis''). The placement of some more poorly known (''Brevidorsum'') or anatomically distinct (''Scapanops'') taxa is less resolved.

Phylogeny

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 Schoch (2012):

Gallery

Platyhystrix BW.jpg, '' Platyhystrix rugosus'', a platyhystricine of the very

late Carboniferous Late may refer to: * LATE, an acronym which could stand for: ** Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia ** Local-authority trading enterprise, a New Zealand business law ** Local average treatment effect, ...

early Permian 01 or '01 may refer to: * The year 2001, or any year ending with 01 * The month of January * 1 (number) Music * '01 (Richard Müller album), 01'' (Richard Müller album), 2001 * 01 (Son of Dave album), ''01'' (Son of Dave album), 2000 * 01 (Urban ...

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

Nooxobeia gracilis (cropped).jpg, '' Nooxobeia gracilis'', an unusually long-legged dissorophid of the early Permian of

Oklahoma Oklahoma (; Choctaw language, Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a U.S. state, state in the South Central United States, South Central region of the United States, bordered by Texas on the south and west, Kansas on the nor ...

Broiliellus olsoni.jpg, '' Broiliellus olsoni'', a dissorophine of the early Permian of

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

Cacops1DB.jpg, ''

'', a eucacopine of the early Permian of Texas Zygosaurus14DB.jpg, '' Zygosaurus lucius'', a eucacopine of the

middle Permian The Guadalupian is the second and middle series/epoch of the Permian. The Guadalupian was preceded by the Cisuralian and followed by the Lopingian. It is named after the Guadalupe Mountains of New Mexico and Texas, and dates between 272.95 ± 0. ...

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

Kamakops1DB.jpg, '' Kamacops acervalis'', a eucacopine of the middle Permian of Russia Anakamacops petrolicusDB20.jpg, '' Anakamacops petrolicus'', a eucacopine of the middle Permian of

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

References

{{Taxonbar, from=Q2463801 Prehistoric amphibian families Carboniferous temnospondyls Permian temnospondyls Pennsylvanian first appearances Lopingian extinctions Taxa named by George Albert Boulenger