Dinocephalia
Encyclopedia
Dinocephalia are a clade
of large early therapsids
that flourished during the Middle Permian, but became extinct leaving no descendants.
and the Eotitanosuchidae, the Dinocephalia are the least advanced among the therapsids, although still uniquely specialised in their own way. They retain a number of primitive characteristics (e.g. no secondary palate
, small dentary) shared with their pelycosaur
ancestors, although they are also more advanced in possessing therapsid adaptations like the expansion of the ilium
and more erect limbs. They include carnivorous, herbivorous, and omnivorous forms, some semi-aquatic and some fully terrestrial, and were also among the largest animals of the Permian period
; only the biggest Caseidae
and Pareiasaur
idea rivalling or even exceeding them in size.
All dinocephalians are distinguished by having interlocking incisor
s allowing a shearing contact between upper and lower teeth. In more advanced forms, the heels on the lingual
sides of the incisor teeth met to form a crushing surface when the jaws were shut, allowing the grinding up of plant matter.
Most dinocephalians also developed pachyostosis
of the bones in the skull, which seems to have been an adaptation for intra-specific behaviour (head-butting), perhaps for territory or a mate. In some types, such as Estemmenosuchus
and Styracocephalus
there are also horn-like structures, which evolved independently in each case.
Dinocephalians are extraordinary for their large size. The biggest herbivores (Tapinocephalus
) and omnivores (Titanosuchus
), may have massed up to two tonnes in weight, and were some 4.5 meters long, while the largest carnivores (such as Titanophoneus
and Anteosaurus
) were at least as long, with heavy skulls 80 cm long, and overall weights of around half a tonne.
-like therapsid that lived in the late Cisuralian epoch. These animals radiated at the expense of the dying pelycosaurs, who dominated during the early part of the Permian
. During the early Capitanian
, advanced dinocephalia radiated into a large number of herbivorous forms; representing a diverse megafauna
. This is well known from the Tapinocephalus Assemblage Zone of the Southern African Karoo
. Shortly after, at the height of their diversity, the dinocephalians suddenly died out. The reason for their extinction is not clear. They were replaced by much smaller Therapsids: herbivorous Dicynodont
ia and carnivorous biarmosuchians, Gorgonopsia
ns and Therocephalia
ns.
Little recent research has been done into dinocephalian relationships. The following arrangement therefore should be taken as provisional only.
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
of large early therapsids
Therapsida
Therapsida is a group of the most advanced synapsids, and include the ancestors of mammals. Many of the traits today seen as unique to mammals had their origin within early therapsids, including hair, lactation, and an erect posture. The earliest fossil attributed to Therapsida is believed to be...
that flourished during the Middle Permian, but became extinct leaving no descendants.
Description
Apart from the BiarmosuchiaBiarmosuchia
Biarmosuchia, also known as Eotitanosuchia and Phthinosuchia, is an assemblage of primitive Permian therapsids that represent either a paraphyletic stem group or a very early off-shoot of the main therapsid tree....
and the Eotitanosuchidae, the Dinocephalia are the least advanced among the therapsids, although still uniquely specialised in their own way. They retain a number of primitive characteristics (e.g. no secondary palate
Secondary palate
The secondary palate is an anatomical structure that divides the nasal cavity from the oral cavity in many vertebrates.In human embryology, it refers to that portion of the hard palate that is formed by the growth of the two palatine shelves medially and their mutual fusion in the midline...
, small dentary) shared with their pelycosaur
Pelycosaur
The pelycosaurs are an informal grouping composed of basal or primitive Late Paleozoic synapsid amniotes. Some species were quite large and could grow up to 3 meters or more, although most species were much smaller...
ancestors, although they are also more advanced in possessing therapsid adaptations like the expansion of the ilium
Ilium (bone)
The ilium is the uppermost and largest bone of the pelvis, and appears in most vertebrates including mammals and birds, but not bony fish. All reptiles have an ilium except snakes, although some snake species have a tiny bone which is considered to be an ilium.The name comes from the Latin ,...
and more erect limbs. They include carnivorous, herbivorous, and omnivorous forms, some semi-aquatic and some fully terrestrial, and were also among the largest animals of the Permian period
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
; only the biggest Caseidae
Caseidae
The Caseidae were a widespread group of very primitive herbivorous synapsids, which appeared during the later early Permian and persisted until the late middle Permian. Although ranging in size from 1 to 5½ meters in body length, caseids were surprisingly conservative in their skeletal anatomy and...
and Pareiasaur
Pareiasaur
The Pareiasaurs - Family Pareiasauridae - are a clade of medium-sized to large herbivorous anapsid reptiles that flourished during the Permian period....
idea rivalling or even exceeding them in size.
All dinocephalians are distinguished by having interlocking incisor
Incisor
Incisors are the first kind of tooth in heterodont mammals. They are located in the premaxilla above and mandible below.-Function:...
s allowing a shearing contact between upper and lower teeth. In more advanced forms, the heels on the lingual
Lingual
Lingual may refer to:* Rap Crew, LINGUAL, an underground widespread hip-hop group from Berlin, Germany. The Group was founded in 2010 with their former member Freddy K. Their music is based on oldschool features with mixtures of Rap, Funk and Jazz and consists of 4 members, Sam-Which, Kurt...
sides of the incisor teeth met to form a crushing surface when the jaws were shut, allowing the grinding up of plant matter.
Most dinocephalians also developed pachyostosis
Pachyostosis
Pachyostosis is a condition in vertebrate animals in which the bones experience a thickening, resulting in unusually solid bone structure with little to no marrow. It occurs in both terrestrial and aquatic vertebrates, such as manatees and dugongs, plesiosaurs, and members of the Dinocephalia...
of the bones in the skull, which seems to have been an adaptation for intra-specific behaviour (head-butting), perhaps for territory or a mate. In some types, such as Estemmenosuchus
Estemmenosuchus
Estemmenosuchus is a genus of large, early omnivorous therapsid that lived during the middle part of the Middle Permian period. It was among the largest animals of its day, and is characterised by distinctive horn-like structures, probably for intra-specific display...
and Styracocephalus
Styracocephalus
Styracocephalus is an extinct genus of Tapinocephalia.-References:* The Origin and Evolution of Mammals by T. S. Kemp*...
there are also horn-like structures, which evolved independently in each case.
Dinocephalians are extraordinary for their large size. The biggest herbivores (Tapinocephalus
Tapinocephalus
Tapinocephalus is a genus of large herbivorous dinocephalian that lived during the Middle Permian Period. These stocky, barrel-bodied animals were characterised by a massive bony skull roof and short weak snout...
) and omnivores (Titanosuchus
Titanosuchus
Titanosuchus ferox was a dinocephalian therapsid that lived in the Mid Permian epoch in South Africa. Despite the name, it was not related to crocodiles....
), may have massed up to two tonnes in weight, and were some 4.5 meters long, while the largest carnivores (such as Titanophoneus
Titanophoneus
Titanophoneus potens was a carnivorous Therapsid of the Dinocephalia group related to the Estemmenosuchidae, but living 5 million years later than Estemmenosuchus, during the Late Permian. Remains of this animal have been found at Isheevo in RussiaAn adult skull would have reached 80 cm with a...
and Anteosaurus
Anteosaurus
Anteosaurus is the name given to an extinct genus of large carnivorous synapsid. It lived during the Capitanian epoch of the Middle Permian in what is now South Africa...
) were at least as long, with heavy skulls 80 cm long, and overall weights of around half a tonne.
Evolutionary history
The dinocephalians evolved from a pelycosaurPelycosaur
The pelycosaurs are an informal grouping composed of basal or primitive Late Paleozoic synapsid amniotes. Some species were quite large and could grow up to 3 meters or more, although most species were much smaller...
-like therapsid that lived in the late Cisuralian epoch. These animals radiated at the expense of the dying pelycosaurs, who dominated during the early part of the Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
. During the early Capitanian
Capitanian
In the geologic timescale, the Capitanian is an age or stage of the Permian. It is also the uppermost or latest of three subdivisions of the Guadalupian epoch or series. The Capitanian lasted between and...
, advanced dinocephalia radiated into a large number of herbivorous forms; representing a diverse megafauna
Megafauna
In terrestrial zoology, megafauna are "giant", "very large" or "large" animals. The most common thresholds used are or...
. This is well known from the Tapinocephalus Assemblage Zone of the Southern African Karoo
Karoo
The Karoo is a semi-desert region of South Africa. It has two main sub-regions - the Great Karoo in the north and the Little Karoo in the south. The 'High' Karoo is one of the distinct physiographic provinces of the larger South African Platform division.-Great Karoo:The Great Karoo has an area of...
. Shortly after, at the height of their diversity, the dinocephalians suddenly died out. The reason for their extinction is not clear. They were replaced by much smaller Therapsids: herbivorous Dicynodont
Dicynodont
Dicynodontia is a taxon of anomodont therapsids or mammal-like reptiles. Dicynodonts were small to large herbivorous animals with two tusks, hence their name, which means 'two dog tooth'...
ia and carnivorous biarmosuchians, Gorgonopsia
Gorgonopsia
Gorgonopsia is a suborder of therapsid synapsids. Their name is a reference to the Gorgons of Greek mythology. Like other therapsids, gorgonopsians were at one time called "mammal-like reptiles"...
ns and Therocephalia
Therocephalia
Therocephalians are an extinct suborder of carnivorous eutheriodont therapsids that lived from the middle and late Permian into the Triassic 265.0—245.0 Ma existing for approximately ....
ns.
Taxonomy
- CLASS SYNAPSIDASynapsidSynapsids are a group of animals that includes mammals and everything more closely related to mammals than to other living amniotes. They are easily separated from other amniotes by having an opening low in the skull roof behind each eye, leaving a bony arch beneath each, accounting for their name...
- Order THERAPSIDA
- Suborder DINOCEPHALIA
- Mnemiosaurus
- ? RhopalodonRhopalodonRhopalodon is a genus of synapsid from the Permian of Russia. It has been variously classified as a dinosaur, a dinocephalian, or another branch of Reptilia. Rhopalodon is notable for being among the first reptiles mentioned in Nature. T.H. Huxley wrote of this reptile, among others, in the...
- ? Family Phreatosuchidae
- PhreatosaurusPhreatosaurusPhreatosaurus is an extinct genus of non-mammalian synapsid.-References:*...
- PhreatosuchusPhreatosuchusPhreatosuchus is an extinct genus of non-mammalian synapsid.-References:*...
- Phreatosaurus
- Family EstemmenosuchidaeEstemmenosuchidaeEstemmenosuchidae are a family of large, very early herbivorous mammal-like reptiles that flourished during the Middle Permian period. They are distinguished by horn-like structures, probably for display or agonistic behavior. Apart from the best known genus, Estemmenosuchus, the group is poorly...
- AnoplosuchusAnoplosuchusAnoplosuchus is an extinct genus of non-mammalian synapsid.-References:*...
- EstemmenosuchusEstemmenosuchusEstemmenosuchus is a genus of large, early omnivorous therapsid that lived during the middle part of the Middle Permian period. It was among the largest animals of its day, and is characterised by distinctive horn-like structures, probably for intra-specific display...
- MolybdopygusMolybdopygusMolybdopygus is an extinct genus of non-mammalian synapsid.-References:*...
- ?ParabradysaurusParabradysaurusParabradysaurus is an extinct genus of non-mammalian synapsid.-References:*...
- ZopherosuchusZopherosuchusZopherosuchus is an extinct genus of non-mammalian synapsid.-References:*...
- Anoplosuchus
- StenocybusStenocybusStenocybus is an extinct genus of dinocephalian therapsid....
- Anteosauria
- Family AnteosauridaeAnteosauridaeThe Anteosauridae or Anteosaurinae are a family or subfamily of very large carnivorous Dinocephalia that are known from the Middle Permian of Russia and South Africa...
(=BrithopodidaeBrithopodidaeBrithopodidae are a paraphyletic family of primitive mostly carnivorous Dinocephalians known from the Middle Permian of Russia. Nowadays the name is used less often, being replaced by Anteosauria Brithopodidae are a paraphyletic family of primitive mostly carnivorous Dinocephalians known from the...
?)- AdmetophoneusAdmetophoneusAdmetophoneus is an extinct genus of non-mammalian synapsid.-References:*...
- AnteosaurusAnteosaurusAnteosaurus is the name given to an extinct genus of large carnivorous synapsid. It lived during the Capitanian epoch of the Middle Permian in what is now South Africa...
- BrithopusBrithopusBrithopus is an extinct genus of dinocephalian therapsid.-Dinosaurus:Dinosaurus, a junior synonym of Brithopus, was first described in 1845 by Johann Fischer von Waldheim, first as a species of Rhopalodon Brithopus is an extinct genus of dinocephalian therapsid.-Dinosaurus:Dinosaurus, a junior...
- ChthomaloporusChthomaloporusChthomaloporus is an extinct genus of Anteosaurian synapsid.-References:*...
- DoliosauriscusDoliosauriscusDoliosauriscus is an extinct genus of dinocephalian therapsid that lived in Russia during the mid-Permian Period. It was a large carnivore, its skull measuring 53 centimeters long.thumb|left|200px...
- Admetophoneus
- Family Deuterosauridae
- DeuterosaurusDeuterosaurusDeuterosaurus is a genus of the Therapsids, one of the "mammal-like” reptiles dominating land during the late Palaeozoic.-Anatomy:Skulls of Deuterosaurus are well-known from several finds. They were around 80 cm with a long snout and conical teeth. Like all anteosaurs, the skull possessed long,...
- Deuterosaurus
- Family SyodontidaeSyodontidaeSyodontidae are a possibly paraphyletic family of smallish primitive carnivorous Dinocephalia. They lack the distinctive 'boss' on the lower jaw, that characterises the Anteosauridae, so they can be considered more primitive. They are known from the Middle Permian Period of what is now Russia...
- AustralosyodonAustralosyodonAustralosyodon is an extinct genus of dinocephalian therapsid.-References:*...
- NotosyodonNotosyodonNotosyodon is an extinct genus of non-mammalian synapsid.-References:*...
- SyodonSyodonSyodon is an extinct genus of dinocephalian therapsid....
- Australosyodon
- Family Anteosauridae
- TapinocephaliaTapinocephaliaThe tapinocephalians are one of the major groups of dinocephalian therapsids. Unlike anteosaurs and estemmenosuchids, tapinocephalians are mainly from Africa and only one species is found in the north - Ulemosaurus from Russia. The tapinocephalians are divided into three clades, Styracocephalidae,...
- Family TapinocephalidaeTapinocephalidaeTapinocephalidae is an advanced family of tapinocephalians. They were all herbivores. They were giants of their time, weighing from 500 to 1000 kg and possibly over 1 or 2 tonnes in weight. They are known from South Africa and Russia. The tapinocephalid skull is very thick, probably used for...
- MoschopsMoschopsMoschops is an extinct genus of therapsid that lived in the Late Permian, around 255 million years ago. Therapsids were proto-mammals , which were the dominant land animals. Five metres long, Moschops was the largest land animal of its time, a herbivore preyed on by other therapsids...
- StruthiocephalusStruthiocephalusStruthiocephalus is an extinct genus of dinocephalian therapsid from the Permian of South Africa.-Sources:*Dinosaur Encyclopedia by Jayne Parsons*The Origin and Evolution of Mammals by T. S...
- StyracocephalusStyracocephalusStyracocephalus is an extinct genus of Tapinocephalia.-References:* The Origin and Evolution of Mammals by T. S. Kemp*...
- TapinocaniusTapinocaniusTapinocanius is an extinct genus of non-mammalian synapsid.-References:*...
- TapinocephalusTapinocephalusTapinocephalus is a genus of large herbivorous dinocephalian that lived during the Middle Permian Period. These stocky, barrel-bodied animals were characterised by a massive bony skull roof and short weak snout...
- TitanophoneusTitanophoneusTitanophoneus potens was a carnivorous Therapsid of the Dinocephalia group related to the Estemmenosuchidae, but living 5 million years later than Estemmenosuchus, during the Late Permian. Remains of this animal have been found at Isheevo in RussiaAn adult skull would have reached 80 cm with a...
- UlemosaurusUlemosaurusUlemosaurus svijagensis was a dinocephalian synapsid that lived 250 million years ago, at Isheevo in Russian Tatarstan.Only several partial skeletons and skulls have been found. The skull bones are extremely dense: about 10 cm at its thickest. This thickening is possibly related to...
- Moschops
- Family TitanosuchidaeTitanosuchidaeThe titanosuchids were carnivorous to omnivorous tapinocephalid dinocephalians. As with other tapinocephalids, they had thick-skulls probably for head-butting. They appeared in the Middle Permian. They had large canine teeth, and their incisors were very strong...
- JonkeriaJonkeriaJonkeria was a very large herbivorous dinocephalian, from the Tapinocephalus Assemblage Zone, Lower Beaufort Group, of the South African Karroo...
- TitanosuchusTitanosuchusTitanosuchus ferox was a dinocephalian therapsid that lived in the Mid Permian epoch in South Africa. Despite the name, it was not related to crocodiles....
- Jonkeria
- Family Tapinocephalidae
- Suborder DINOCEPHALIA
- Order THERAPSIDA