Anteosaurs are a group of large, primitive
carnivorous
A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other ...
dinocephalia
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinoceph ...
n
therapsid
Therapsida is a major group of eupelycosaurian synapsids that includes mammals, their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented mor ...
s with large canines and incisors and short limbs, that are known from 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 ...
of South Africa, Russia, China, and Brazil. Some grew very large, with skulls long, and were the largest predators of their time. They died out at the end of the Middle Permian, possibly as a result of the extinction of the herbivorous
Tapinocephalia
The Tapinocephalia are one of the major groups of dinocephalian therapsids and the major herbivorous group. Tapinocephalia has been found to consist of three clades: Styracocephalidae, Titanosuchidae, and the very successful Tapinocephalidae. ...
on which they may have fed.
Description

The Anteosauria are distinguished from the Tapinocephalia by a number of features, such as very large
canines, cheek teeth with bulbous
crowns, and an upturning of the
premaxilla
The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...
, so that the front of mouth curves strongly upwards. There is a tendency especially in more advanced forms such as ''
Anteosaurus'' towards thickening of the bones of the top of the skull, indicating head-butting behaviour. There is a large canal for the pineal organ (third eye); probably tied in with the animal's diurnal and seasonal cycles.
The shoulder girdle is fairly light, with a narrow interclavicle, clavicle, and scapular blade. The femur (thigh bone) is slender and curved. These were, in spite of their size, probably quite agile animals. The limbs are short and the skull long, narrow, and heavy. The tail is very long in at least some genera.
Evolutionary relationships
The early Russian (Boonstra 1972) and Chinese (Rubidge & Sidor 2001) anteosaurs are generally considered the most primitive of the dinocephalians, although it has also been suggested (Kemp, 1982, King 1988) that the
estemmenosuchids are more
basal
Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''.
Science
* Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure
* Basal (medicine), a minimal level that is nec ...
. They have featured in common with
pelycosaurs (Carroll 1988) and
Biarmosuchians (Chudinov 1965), and, with the Tapinocehalia, are part of the first major evolutionary radiation of the Therapsida (Rubidge & Sidor 2001). So far, little work has been done on detailed
phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
relationships between the various
taxa
In biology, a taxon ( back-formation from '' taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular n ...
.
Palaeobiology
Ecology

The stance of a typical anteosaur, such as ''
Titanophoneus'', was primitive. Rather than the limbs being drawn in under the body, the stance was more sprawling. Olson (1962) notes that the Russian dinocephalian assemblages indicate environments tied to water, and Boonstra considered that the roughly contemporary ''
Anteosaurus'' was a slinking crocodile-like semi-aquatic form. The long tail, weak limbs, and sprawling posture do indeed suggest some sort of crocodile-like existence. However, the thickened skull-roof indicates that these animals were quite able to get about on land, if they were to practice the typically dinocephalian head-butting behavior. All other head-butters;
pachycephalosaurian
dinosaurs
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
,
titanothere ungulates, and
goat
The goat or domestic goat (''Capra hircus'') is a domesticated species of goat-antelope typically kept as livestock. It was domesticated from the wild goat (''C. aegagrus'') of Southwest Asia and Eastern Europe. The goat is a member of ...
s were or are completely terrestrial. Perhaps these animals spent some time in the water but were active on land during the mating season, and probably quite able to get about on land to hunt for prey.
Feeding
Anteosaurs were evolved to prey on particularly large animals and were among the most highly predaceous of all synapsids (Sennikov, 1996), potential prey included the bull-sized armored
pareiasaurs (Lee, 1997) and
enormous
tapinocephalid
Tapinocephalidae was an advanced family of tapinocephalians. It is defined as the clade containing '' Ulemosaurus'', ''Tapinocaninus'', and the Tapinocephalinae. They are known from both Russia and South Africa. In all probability, the Tapinocep ...
dinocephalians (Rubidge, 1995).
The large anteosaurs were efficient predators, more specialized than earlier and more primitive
biarmosuchid and
eotitanosuchid carnivorous therapsids, as the temporal opening behind the eye socket was larger, indicating a greater muscle mass available for closing the lower jaw. Large pterygoid flanges indicate a well-developed KI system in anteosaurs, and increased vertical alignment of the temporalis muscles suggests an expanded SP component of the bite cycle.
[
]
Classification
Phylogeny
James Hopson
James Allen Hopson (born 1935) is an American paleontologist and professor (now retired) at the University of Chicago. His work has focused on the evolution of the synapsids (a group of amniotes that includes the mammals), and has been focuse ...
and Herbert Barghusen in 1986 provided the first cladistic
Cladistics (; ) is an approach to biological classification in which organisms are categorized in groups (" clades") based on hypotheses of most recent common ancestry. The evidence for hypothesized relationships is typically shared derived ch ...
study of the Therapsida. They used the term "Anteosauria" and synonymised the families Brithopodidae and Anteosauridae. In 2010, Christian Kammerer published a re-evaluation of anteosaurian relationships.[Kammerer, C. (2010). Systematics of the Anteosauria (Therapsida: Dinocephalia). ''Journal of Systematic Palaeontology'', 9(2): 261-304. ]
The 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 ...
below follows an updated (2012) version of Kammerer's analysis by Juan Carolos Cisneros and colleagues.[Cisneros, J.C., Fernando Abdala, Saniye Atayman-Güven, Bruce S. Rubidge, A. M. Celâl Şengör, and Cesar L. Schultz. (2012). Carnivorous dinocephalian from the Middle Permian of Brazil and tetrapod dispersal in Pangaea. ''PNAS'', 109 (5): 1584-1588. ]
Taxonomy
The group was originally defined as a superfamily by L. D. Boonstra in 1962 to include the families
Brithopodidae and Anteosauridae.
*Superfamily Anteosauroidea Boonstra, 1962
**Family Brithopidae Efremov, 1954
**family Anteosauridae Boonstra, 1954
Gillian King in a 1988 review of the Anomodont
Anomodontia is an extinct group of non-mammalian therapsids from the Permian and Triassic periods. By far the most speciose group are the dicynodonts, a clade of beaked, tusked herbivores.Chinsamy-Turan, A. (2011) ''Forerunners of Mammals ...
ia (including the Dinocephalia - however the view that the Dinocephalia are a subset of the Anomodontia is no longer held) as part of Gutsav Fischer Verlag's ongoing ''Encyclopedia of Paleoherpetology'' series of volumes, uses a more traditional Linnaean arrangement, but includes the herbivorous forms under the superfamily Anteosauroidea as well. The "Titanosuchidae" here is equivalent to the "Tapinocephalia
The Tapinocephalia are one of the major groups of dinocephalian therapsids and the major herbivorous group. Tapinocephalia has been found to consist of three clades: Styracocephalidae, Titanosuchidae, and the very successful Tapinocephalidae. ...
".
*Superfamily Anteosauroidea Boonstra, 1962
**Family Brithopidae Boonstra, 1972
***Subfamily Brithopodinae Efremov, 1954
***Subfamily Anteosaurinae Boonstra, 1954
**Family Titanosuchidae Boonstra, 1972
***Subfamily Titanosuchinae Broom, 1903
***Subfamily Tapinocephalinae Lydekker, 1890
After Kammerer et al., 2011.
* CLASS Synapsida
** Order Therapsida
*** Suborder Dinocephalia
Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinoceph ...
**** Clade Anteosauria
***** Family Anteosauridae
****** '' Archaeosyodon''
****** '' Microsyodon''
****** Subfamily Anteosaurinae
******* '' Sinophoneus''
******* '' Titanophoneus''
******* '' Anteosaurus''
****** Subfamily Syodontinae
******* '' Australosyodon''
******* '' Notosyodon''
******* '' Pampaphoneus''
******* ''Syodon
''Syodon'' is an extinct genus of dinocephalian therapsids that lived approximately 267-260 million years ago during the middle Permian period of the Paleozoic era. These therapsids, located in Russia were initially believed to be true mammals ...
''
***** Family Brithopodidae
****** ''Admetophoneus
''Admetophoneus'' is a dubious genus of non-mammalian synapsid from Russia. Its type and only species is ''Admetophoneus kargalensis''.
History
''Admetophoneus'' was named by the Russian paleontologist Ivan Efremov in 1954, based on some teeth ...
''
****** '' Brithopus''
****** '' Chthomaloporus''
****** ''Eosyodon
''Eosyodon'' is a dubious genus of extinct non-mammalian synapsids from the Permian of Texas. Its type and only species is ''Eosyodon hudsoni''. Though it was originally interpreted as an early therapsid, it is probably a member of Sphenacodonti ...
''
****** '' Mnemeiosaurus''
***** Family Deuterosauridae
****** '' Deuterosaurus''
References
Further reading
* Boonstra, L.D., 1972, Discard the names Theriodontia and Anomodontia: a new classification of the Therapsida. Annals of the South African Museum 59:315-338.
* Carroll, R. L., 1988, ''Vertebrate Paleontology and Evolution'', WH Freeman & Co.
* Chudinov, P. K. 1965, "New Facts about the Fauna of the Upper Permian of the USSR", '' Journal of Geology'', 73:117-30
* Hopson, J.A. and Barghusen, H.R., 1986, An analysis of therapsid relationships in N Hotton III, PD MacLean, JJ Roth and EC Roth, ''The Ecology and Biology of Mammal-like Reptiles'', Smithsonian Institution Press, pp. 83–106
* King, G.M., 1988, "Anomodontia" Part 17 C, ''Encyclopedia of Paleoherpetology'', Gutsav Fischer Verlag, Stuttgart and New York,
* Rubidge, B.S. & Sidor, C.A. 2001, Evolutionary patterns among Permo-Triassic therapsids. '' Annu. Rev. Ecol. Syst.'' 32: 449-480.
External links
Palaeos
- detailed description
- list of genera in the form of 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 ...
{{Taxonbar, from=Q987337
Guadalupian first appearances
Guadalupian extinctions