Middle and Late Permian Therapsids
In the Permian period, all major land masses were joined in the mega-continent Pangea, which formed from the juncture of two supercontinents, Laurasia in the north and Gondwanaland in the south. These had gradually assembled during the preceding Devonian, Mississippian, and Pennsylvanian periods. Pangea lasted through the Permian and into much of the subequent Triassic period, before the rocky plates representing the continents began to separate.
indicator of the connection
of land masses in the
is the distribution of the same species in continental areas now
separated by oceans.
A good example of this is the conifer Glossopteris,
an important Permian forest element preserved in
woody, seed-bearing tree, growing as high as 30 meters, and
interpreted to have
thrived in very wet soil
conditions, such as around swamps and along river banks. Fossils
have been found in
all of the southern continents (fig.1), with over 70 species identified
Fig.1: Distribution of Glossopteris (green area) in southern Pangea.
The zone of Glossopteris
(fig.1) across several, now detached,
Austrian geologist Eduard
Suess (1885-1909) to infer that
these areas had once been connected
by a land
bridge, with the continents remaining in the same position.
expressed in his major work, The
Face of the Earth
(1885-1909), Suess also believed that
the rise and fall of sea levels were mappable across the earth through
geological time, and that the
periods of ocean transgression and regression could be correlated from
continent to another. He
named the interconnected southern land mass
the district in
Shortly thereafter, the German
and polar researcher Alfred
Wegener (1880-1930) more
accurately interpreted that the land
masses themselves had moved together by shifting continental plates.
theory of Continental Drift (1912, 1929), hypothesizing that the
continents were slowly moving around the
Earth, was not widely accepted for several decades. Among its most
vocal opponents was the American paleontologist George Gaylord Simpson
(1943). Wegener's theory began to gain wide acceptance in the
early 1950s, when paleomagnetic samples
Pangea is the setting for the first appearance in the fossil record of mammal-like reptiles or theriodonts, the ancestors of mammals, during the Middle and Late Permian (268-251 mya). The clearest exposure of this lies in a portion of the southern region of Gondwanaland, centering in South Africa.
South Africa: Karoo Basin
The best continuous fossil record from the Middle Permian through Early Triassic periods has been found in the Karoo Basin of South Africa. This sedimentary basin is bounded on the south by the Cape Fold Mountains, which were uplifted in the Early to Middle Permian period by tectonic plates converging on those of South Africa (Rubridge 1995).
The geological formations in the Karoo Basin include a succession of five groups (Dwyka, Ecca, Beaufort, Stormbert, and Drakensberg), dating from the Late Carboniferous through Jurassic periods (fig.2). The third of these, the Beaufort Group, is the lowest terrestial formation, overlying shallow marine shales of the Ecca Group. Beaufort Group rocks consists of shales and sandstones that represent riverine deposits of an ancient sedimentary basin. Its importance for paleontology stems from its having provided a comprehensive series of often well-preserved fossil zones, including a continuous record of flora and fauna dating from the Middle Permian through Middle Triassic periods (270-220 mya) (Rubridge 1995).
Fig.2: Geological formations in the Karoo Basin of South Africa.
Fossil evidence of Therapsids ("beast faces"), the ancestors of mammals, first appear in the Middle Permian deposits of the Beaufort Group in South Africa. Three suborders of Therapsids will be briefly traced below in their appearance in the Beaufort faunal zones: the Anomodontia ("undefined teeth"), the Dinocephalians ("terrible heads"), and the Theriodonta ("beast teeth"). The theriodonts became one of the two synapsid survivors of the great Permian–Triassic extinction event, the other being the dicynodonts, part of the Anomodontia. Theriodonts split into two groups, Therocephalians ("beast heads") who died out after the Early Triassic; and cynodonts ("dog teeth"), whose carnivorous forms became progressively smaller during the Triassic. By the Late Triassic the first mammals evolved from small, shrew-sized cynodonts called trithelodonts.
The Beaufort group has been subdivided into eight faunal assemblage zones (A.Z.), each associated with one or more local geological formations, and each containing a number of associated taxa (fig.3). 1. Eodicynodon A.Z., Abrahamskrall Formation; 2. Tapinocephalus A.Z., Abrahamskraal Formation; 3. Pristerognathus A.Z., Koonap and Middleton Formations; 4. Tropidostoma A.Z. Middleton Formation; 5. Cistecephalus A.Z., Middleton and Balfour Formations; 6. Dicynodon A.Z., Balfour Formation; 7. Lystrosaurus A.Z, Balfour and Katberg Formations; 8. Cynognathus A.Z., Burgersdorp Formation (Rubridge 1995).1. Eodicynodon Assemblage Zone. This dates from the Middle Permian, Wordian stage (268.8-265.9 mya), and occurs at the southwestern edge of the Abrahamskraal Formation, the lowest zone of continental rocks in the Karoo Basin. This is composed of thick layers of fluvial-deposited shale or mudstones totalling 1400-1800 m in depth, with a higher percentage of sandstone, limestone, and chert than in the overlying Teekloof Formation (Keyser and Smith 1978).
The Abrahamskraal layers,heavily folded to the south, directly overlie marine-deposited shale of the Ecca Group's Waterford Formation. The intersection of the Waterford and Abrahamskraal Formations represents the paleoshoreline at about 270-269 mya (Rubridge 2000; Modesto et al. 2001).
Fig.3: Stratigraphy of the Beaufort Group Faunal Zones. Skulls used as examples: 1. Eodicynodon. 2. Robertia. 3. Pristerognathus. 4. Lycaenops 5. Cistecephalus. 6. Dicynodon. 7. Lystrosaurus. 8. Cynognathus.
is named for the small
double dog-tooth"), the earliest known genus of
found as a skull
The huge, semiaquatic carnivore Anteosaurus magnificus ("great earlier lizard"), the type species for the Anteosauridae, was named by Watson in 1921. Up to 5 meters in length, and with a notably long skull (fig.4), it had prominent interlocking incisors, large canine teeth, and ten additional cheek teeth on each side (Boonstra 1954). Anteosaurus probably lived as a river predator, something like a modern crocodile. The giant Anteosaurus existed in South Africa at the same time that Titanophoneus and Doliosauriscus dominated riverine environments in the Isheevo region in western Russia.
Fig.4: Skull of Anteosaurus magnificus, from the Mid Permian.
Anteosaurus, defined by a relatively lage sample well-preserved skulls, shows distinctive traits in both its elongated, primitive skull form, and enlarged canine teeth which were related to its carnivorous feeding habits. These traits were passed on to its later descendants such as the Titanosuchidae, many of which, however, changed their dietary habits to become omnivores or herbivores. In terms of their roles as carnivores, the family Anteosauridae were replaced in the Late Permian by large gorgonopsians (described below).
The second family of dinocephalians from this zone are the Titanosuchidae, considered direct descendants of Anteosauridae. Titanosuchidae include the genera Titanosuchus and Jonkeria, whose skulls show close similarities, retaining the primitive form of the anteosaurs, including a thickened frontal bone at the top, with a large pineal foramen. The skeletal anatomy among the Titanosuchidae, however, often differs significantly between genera, as presumbly did their eating habits. The type species, Titanosuschus ferox ("fierce Titanic crocodile") is considered to have been a carnivore (King 1988). It measured over 2.5 meters in length, had a massive skull, and had curved, fang-like canines and sharp incisors, like those of Anteosaurus.
A second genus from the same family, Jonkeria, is thought to have been a partial herbivore, sometimes eating plants (King 1988). Jonkeria ingens (fig.5), defined by Broom (1929), was 4-5 m long, almost as large as Anteosaurus, with long, stout limbs. It had a typically long, dinocephalian snout, with large incisors and canines. A total of six Jonkeria species have been named (Boonstra 1969).
Fig.5: Skeleton of Jonkeria ingens.
The third family from this zone, the Tapinocephalidae, are also known in Russia, and probably had an even wider distribution in the Middle Permian, before becoming extinct at the end of the Capitanian stage. Primarily herbivores, their short, high skulls contrast significantly with the long, primitive skulls of the prevous two families (Anteosauridae and Titanosuchidae). The Tapinocephalidae were among the largest animals of their age, weighting up to 3,000 - 4,500 pounds, with large, rounded midsections, as is typical for plant-eaters. Their teeth have chisel edges, and (also in contrast to the previous two families) lack the specialized canines of carnivores. Their relatively short, sturdy forelegs extended outwards, while the longer hind legs were placed directly under the hips (similar to that of the Late Permian dicynodonts). Based on comparisons with some modern herbivores, they could stand bipedally and eat vegetation directly from lower tree branches.
Tapinocephalus atherstone (fig.6),, the type species for this family, and the only known species of the genus, was a large herbivore up to three meters long, weighing an estimated 3,300-4.400 pounds. Their skulls are characterized by massive frontal bones in the skull roof, and short snouts.
Fig.6: Skull of Tapinocephalus atherstonei, shown in overhead and lateral views (after Smith and Keyser 1995, fig.12a).
Another large herbivore from the same family was Moschops capiensis (Broom 1911). Moschops ranged from 2.5 - 5.0 m in length, with a large, rounded midsection. They had a high, short skull, with short jaws and chisel-shaped teeth. There are two widely-accepted species, M. capensis and M. koupensis, both found within the same stratigraphic range of the Beaumont Formation.
The pareisaurs are represented in this zone by Bradysaurus (figs.7,14), another large herbivore. Bradysaurus had heavily armored scales on its head and neck for protection against gorgonopsians and other predators.
Fig.7: Skeleton of Bradysaurus (Berlin Mus. Nat. Hist.)
3. Pristerognathus Assemblage Zone (late Middle Permian). This narrow zone, skirting the eastern edge of the much larger Tapinocephalus zone contains the first evidence of the carnivorous Gorgonpsida ("gorgon faces"), the most primitive group of theriodonts ("beast teeth"). The other two groups, Therocephalia ("beast heads") and Cynodontia ("dog teeth") are grouped as Eutheriodonts, "true beast teeth". The Eutheriodonts have larger skulls, with larger brains related to improved hearing and vision, and improved jaw muscles related to enlarged lower jaw bones (dentaries), a mammal-like trait which enabled more effective chewing. The early theriodonts were carnivorous; later, during the Triassic, several groups became herbivorous.
The zone is named for Pristerognathus, a medium sized therocephalian carnivore discovered by Broom in 1904, growing up to 1.5 meters in body length. These otter-sized animals had long, narrow skulls with large canines, and probably hunted smaller therapsids and reptiles. Three species include P. baini, P. polyodon, and P. platyrhinus.
At this point, another major change was occurring in the theriodonts, in the miniaturization of several smaller bones in the rear of the lower jaw (the reptilian quadrate, articular, and surangular bones), and their transformation into the tiny ossicle bones of the mammalian middle ear (stapes, incus, and malleus). This process, completed by the Late Triassic, led to the much improved hearing of mammals, as compared to reptiles who have only the stapes in the middle ear to amplify airborne sounds. Improved hearing helped make the theriodonts the most successful group of synapsids. The two diagnostic traits of the middle ear with three ossicles, and the related changes in the lower jaw joint, are the two most commonly used guides in the fossil record to distinguish early mammals from non-mammal synapsids as well as reptiles.
Permian). This zone, dating from the Late Permian (Tatarian stage) is
named for the early dicynodont, Tropidostoma
("keel mouth"), first
reported by Seeley (1889) and Broom (1915)
The Cistecephalus Zone shows a peak in dicynodont diversity, including about 35 genera. By this time in the Late Permian, the larger dicynodonts have radiated to other parts of Gondwanaland (King 1990)
.This genus has also been identified in India (Bandyopadhyay 1988) and Zambia. A very similar genus, Kawingasaurus, is also known from the Kawinga Formation of Tanzania, considered equivalent to the Cistecephalus zone.
Dicynodon Assemblage Zone
257-252 mya). This extensive, ring-shaped zone is
named for Dicynodon
("Two Dog-teeth"), the type species of the dicynodonts, first described
in the mid 19th century. It is a
medium-sized, herbivorous therapsid about 1.2 meters long, with no
teeth except for two prominent, tusk-like canines (fig.8). It probably
cropped vegetation with
a horny beak, much like a tortoise, while the tusks may have been used
digging up roots and tubers. The type
species is Dicynodon
lacerticeps, named by Owen
over 160 species
have since been
named from various Late Permian formations in Russia , China, India,
and elsewhere, these have recently been reclassified. A recent study of
genus determined the
only valid members of the genus to be D.
South Africa, and D. huenei
Fig. 8: Skull of Dicynodon.7. Lystrosaurus Assemblage Zone (Early Triassic; 252-247 mya). While most of the Permian species described from the previous six faunal zones were eliminated by the massive extinction event at the end of the Permian, some dicynodonts and cynodonts from the Karoo Basin survived, and their fossils are found in Early Triassic layers of the Beaufort Group. The first faunal zone of the Early Triassic in South Africa (fig.6) is named for the small dicynodont Lystrosaurus, a widely dispersed genus who is by far the most commonly found terrestial animal during the Early Triassic. Lystrosaurus will be further discussed in later sections on the Triassic period.
8. Cynognathus Assemblage Zone (Early Triassic, 247-242 mya). This zone, located on the inner edge of the Beaufort Group (fig.6), will likewise be discussed in later sections.
.Late Permian dicynodonts: variation and distribution
Dicynodonts, well represented in the three Late Permian faunal zones described above for the Karoo Basin of South Africa, and surviving through into the Early Triassic, were a widely distributed group in the southern land areas of Gondwanaland. First appearing in the Middle Permian zones of the Beaufort Group, they became the most successful and abundant land vertebrates of the Late Permian, radiating into a varety of niches in widespread regions as large, medium-sized, and small herbivores, and short-limbed burrowers.
They were first reported in 1845 by
Geddes Bain from fossils he found during surveys of
As members of the Synapsids, the single temporal opening of dicynodonts is greatly enlarged, supporting very powerful jaw muscles. Their dentition, while somewhat variable, was usually minimal. Many genera, including the type genus Dicynodon, had a complete absence of teeth, apart from their prominent upper canines (fig.8). Some dicynodonts such as Oudenodon had no teeth at all; others, however, such as Pristerodon, had several post canine teeth for chewing, in addition to large canines. One widely distributed genus, Enthiodon, had two rows of 9-11 teeth on the palatine bones of its upper jaw, and matching teeth in its dentary or lower jaw bone, as described by Owen (1879). More consistently, the dentary processes of dicynodonts were made up of a horny, keratin covering on both the upper and lower jaws. This formed a beak-like appearance, resembling that of modern turtles.Regarding their reproduction, it remains unknown whether dicynodonts laid eggs, as in reptiles, or had developed vivipary, as in mammals. The bony birth canal area between the pubis and ischium was large enough to allow the birth of live young, but could also have been useful in laying large eggs (King 1990).
Some genera display sexual dimorphism, as shown by larger canine teeth in males.
A distribution map (fig.9) shows the areas in Gondowanaland where fossils of four widespread Late Permian dicynodont genera have been found (Ray 1999). These include Cistecephalus (already discussed as the type genus for a faunal zone), Endothiodon, Pristerodon, and Oudenodon. Based on the overlapping distribution pattern of the widespread conifer Glossopteris, these animals probably lived in wooded, well-watered, riverine settings.
showing distribution of four Late Permian dicynodonts
EndothiodonThe Late Permian dicynodont Endothiodon (fig.10) was first described by Owen (1879) for the Karoo region, with a skull and mandible, including 11 teeth located in the palatines. A partial skeleton was later recovered by Broom (1915) at Beaufort West in South Africa, from the Hoedemaker member of Middle Teekloof Formation, dating from the Late Permian Tatarian Age. Endothiodon augusticeps is one of the species found in South Africa. Since then, Endothiodon has also been found in Tanzania (Haughton 1932), Zambia (Mazin and King 1991), Mozambique (King 1992), India (Kutty 1970), and Brazil (Boos et al. 2013).
Fig.10: Endothiodon skeleton (after Broom 1915; AMNH) .
The finding of Endothiodon in Brazil is particularly noteworthy, since it is the first dicynodont to be reported for the Permian of South America. A partial skull and associated lower jaw were discovered in the 1970s in a railway cut at Serra do Cadeado, in the Rio do Rasto Formation of Parana State in Brazil (Barbarena and Araujo 1975). The Rio de Rasto Formation is dated at Ufimian to Early Tatarian age, in the Guadelupian Stage of the Middle Permian. The fossils were initially assigned to the genus Endothiodon Owen, which implied a direct correlation of the Brazil specimen with the taxon from the Beaufort Group in South Africa.
Boos et al. (2013) recently reexamined the specimen (FURB PV0226), and have confirmed its original assignment by Barbarena and Araujo to the genus Endothiodon. This is based on several key anatomical features, such as the pineal foramen being located on a boss or small protrusion, a bulbous swellings of the dentaries, a boss situated on the ventral margin of the jugal, an extensive number of dentary teeth, and an upturned pointed beak of the lower jaw (Boos et al. 2013). Further analysis is considered necessary to determine the exact species identification.
Another interesting facet of the findings of Boos et al. pertain to biostratigraphical correlations they propose for the tetrapod faunas of the Rio do Rasto Formation. These show similarities with stratigraphic ranges of the Middle and Late Permian of both South Africa and Eastern Europe. As Boos et al. (2013) state, the presence of Endothiodon shows that part of the Rio do Rasto Formation in Brazil can now be correlated with deposits in India, Malawi, Mozambique, South Africa, Tanzania, Zambia, and Zimbabwe.Pristerodon
Fig.11: Pristerodon skull (A) and lower jaw (B), showing teeth (after Benton 2005)
Oudenodon is the type genus of the family Oudenodontidae, which also includes Cteniosaurus, Tropidostoma, and Rhachiocephalus. The Oudenodontidae family have a deep, thin walled cleft in the lower jaw for anchoring the horny platform. They had a very precise cutting and crushing surface between the beaks, where the rim of the maxilla was pointed downward to fit with the lower jaw symphesis. Oudenodon (fig.12) had no teeth at all. The skull was directed forwards, therefore, adapted to feeding at levels approximately 20-100 cm above the ground (King 1990). This shows a new level of diversification, away from substrate-feeding.
Fig.12: Oudenodon skull, showing beak-like jaws (Berlin Museum of Natural History)
Oudenodon was common throughout southern Africa during the Late Permian, and has also been found in India (Ray 1999; Bandyopadhyay 1999), Madagascar, and Zambia. Several known species of Oudenodon include Oudenodon bainii, the type species, and O. grandis from South Africa, and O. luangwensis from Zambia. Another species, O. sakamenensis, is the only therapsid yet known from Madagascar (Mazin and King 1991).
Gorgonopsians: the main Late Permian predators
Gorgonopsians (Gorgon and -ops-, "eye" or "face" = "Gorgon faces"), are the most primitive of the three groups of theriodonts found in the Karoo Basin, the other two being therocephalians and cynodonts. During the Late Permian, the gorgonopsians were a highly successful group, including a total of 25 genera and 41 species, from South Africa, Tanzania, Zambia, and Malawi, as well as from Russia (Sigogneau-Russell 1989; Ivokonenko 2005; Gebauer 2007).
Fig.13: Skeleton of Sauroctonus, a Late Permian gorgonopsian found in Russia and Africa (Gebauer 2007)
During the Late Permian, gorgonopsians became much more common, with the genera Gorgonops, Eoarctops, Lycaenops, Sauractonus (figs.13,16) Arctognathus, Njalila, Clelandina, and Rubidgea being found in the Tropidostoma and Cistecephalus Zones dated at 260-255 mya (Rubidge 1999; Smith and Keyser 1995). In the Dicynodont Zone (255-252 mya) occur the latest forms of Gorgonopsians, including Cynosaurus, Prorubidgea, and Rubidgea, the latter with extremely enlarged canines. Gorgonopsians then became extinct as part of the mass extinction at the end of the Permian (251 mya), with the other two theriodont groups continuing into the Triassic (Rubidge et al. 1995; Gebauer 2007).
Fig. 14: Skull of Bradysaurus seen from above and from the side, showing the rough, scaly armor used as a defense against predators (after Smith and Keyser 1995).
Gorgonopsians were among the largest carnivores of the Late Permian. Most of the known forms, such as the type genus Gorgonops, were 1.5 - 2 meters in length, about the size of lions and other large felids. The largest known genus was Inostrancevia, found in Late Permian deposits in the Northern Dvina Valley in Russia, in the Sokolki assemblage (Efremov 1937; Ivakhnenko 1990). Inostrancevia was over 3 meters long, about the size of the largest modern bears, with a skull length of 45 cm, and saber-like canine teeth up to 12 cm long.
The mammal-like traits of gorgonopsians include differentiated or heterodont teeth, with incisors, canines, and cheek teeth or molars; a large, fully developed temporal fenestra for strong jaw muscle attachment; and vertically-aligned rear legs for faster movement. Gorgonopsids also had a vaulted palate that may have facilitated breathing while holding prey in their jaws; and early stages of the hearing ossicles that later developed in the mammalian middle ear.
torvus, was first identified on
the basis of an incomplete and
skull found in South Africa at Mildenhalls,
The type genus Gorgonops, like most members of the family gorgonopsidae, has a body length of 1.2-2 meters and a skull length of 22-35 cm. Its formidable array of teeth included the large canines, which had serrated edges, and five incisors. Besides G. torvus, among the earlier species to be described were the larger Gorgonops whaitsi (Broom, 1912), found in the Tropidostoma and Cistecephalus Zones in the Beaufort West area. Sigogneau-Russell (1989) considered this a more primitive form than G. torvus. A third and still larger species, which may be descended from G. whaitsi, is Gorgonops longifrons (Haughton 1915), known from an incomplete and flattened skull about 35 cm long, with larger eye orbits and a longer snout.
Fig.15: Skeleton of Lycaenops, a Late Permian gorgonopsian found in the Beaufort Group (photo: after Gebauer 2007)Lycaenops ("Wolf-face"), found in the Late Permian Endothiodon Zone, was another medium-sized gorgonopsian, with more enlarged canines. The first named species of this genus was Lycaenops ornatus (fig.15), whose type specimen was a nearly complete skeleton found by Broom in 1920 on a weathering shale slope near a railway line, two miles south of the railway station at Biejespoort, South Africa. Stratigraphically, it was at the very top of the Endothiodon zone, within the Teekloof Formation of the Karoo Basin. Some carpal bones of the hands and feet had weathered away along with most of the tail and cervical region, but otherwise the skeleton was intact, a rarity for Gorgonopsia fossils (Broom 1930, pp.349-50; Colbert 1948).
Regarding the undoubted identity of gorgonopsians as Late Permian "saber-toothed" carnivores, Colbert observed that the condition of hypertrophy of the canines, accompanied by a deepening of the anterior part of the lower jaw, is well represented in Lycaenops ornatus, but is seen at its most advanced form in the late gorgonopsians Inostrancecia and Rubidgea (Colbert 1948, pp.373-375). More recently, Gebauer (2007) has made a detailed comparison between the gorgonopsian Sauroctonus (figs.13,16), first described from the Northern Dvina region in Russia (Tatarinov 1974), and the saber-toothed cat Smilodon fatalis (fig.17), which had similar body lengths of about 2 meters.
and anterior portion of the
skeleton of Sauroctonus parringtoni,
from the Upper Permian in the
In spite of the fact that they are separated by at least 230 million years, and that Sauroctonus still retained some reptilian features in its lower jaw, skull, and skeleton, while Smilodon was an advanced mammal, there are some intriguingly close functional parallels between these two extinct carnivores, both in teeth and jaw forms, and the musculature of jaw movements used in catching and eating prey.
The lower jaws of gorgonopsians, for example, had a thicker front portion than the rear portion, protecting the enlarged canine teeth; a similar function was performed by bone flanges of saber-toothed cats. After a detailed analysis, Gebauer concludes that "it can be well imagined that Sauroctonus in all probability occupied the same ecological niche [as] its mammalian relative 230 million years later" (Gebauer 2007).
Fig.17: Skeleton of the saber-toothed cat Smilodon fatalis (after Gebaur 2007).
Gorgonopsians in Tanzania, Malawi, and Zambia
Haughton (1927) later described two gorgonopsian genera found in Malawi, Gorgonops and Aelurognathus (fig.18), the latter genus previously named by Owen (1881). Boonstra (1934), based on analysis of post-cranial anatomy, described two species of the genus Aleruognathus, and one of the genus Arctognathus.
(1953) later described gorgonopsians
from Tanzania, as did Parrington
(1955, 1972), including those
found by the German engineer Nowack in the 1930s. Identified taxa
Aloposaurus, Leontocephalus, Dinogorgan, Sauroctonius, and possibly Arctognathus (Gebauer 2007). Including the Tanzanian materials, Kemp (1982, 2005) has made detailed comparisons of gorgonopsian skull and skeletal anatomy with other synapsids. More recently, Gebauer (2007) reanalyzed one of the best preserved of the Tanzanian specimens, a nearly complete skeleton originally described as Aelurognathus, now identified as a variant of the Russian genus Sauroctonius (Tatarinov 1974).
Fig.18: Skull of Aelurognathus, a Late Permian gorgonopsian found iin Tanzania, Malwai, and Zambia, as well as South Africa.From Zambia, specimens have been identified as Aelurognathus by Sigogeneu (1970). In general for the gorgonopsians, many problems in redundant classifications (such as addressed by Colbert in 1948) were sorted out by Sigogneau-Russell (1989), although some difficulties remain, given the number of gorgonopsian taxa and the wide geographical range of their presence.
The most primitive known gorgonopsians are pelycosaur-like forms in Late Permian Russia, including Biarmosuchus and Eotitanosuchus from Ezhevo. They are contemporary with more advanced forms from South Africa, and thus can provide no simple answers to the origins of gorgonopsians. Other, more derived Russian forms include Sauroctonius, Viatkogorgon, and Suchogorgon (Tatarinov 1974, 1999, 2000; Ivakhnenko 1990). These and other Russian taxa are discussed in the following section.
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