Sauroctonus Temporal range: | |
---|---|
Overview of PIN 156/5, the lectotype skull of S. progressus | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Synapsida |
Clade: | Therapsida |
Clade: | † Gorgonopsia |
Family: | † Gorgonopsidae |
Genus: | † Sauroctonus Bystrow, 1955 |
Type species | |
†Sauroctonus progressus Hartmann-Weinberg, 1938 | |
Other species | |
| |
Synonyms | |
Synonyms of S. progressus
Synonyms of S?. parringtoni
|
Sauroctonus ("lizard killer") is an extinct genus of gorgonopsian therapsids who lived during the end of the Middle Permian in what is now European Russia. The first fossils, discovered in Tatarstan, were first considered to belong to a new species of the South African genus Arctognathus , named A. progressus in 1938. The taxon will be designated as such until 1940, when it will be assigned to the genus Inostrancevia by Ivan Yefremov, before being definitively classified in a separate genus erected by Alexey Bystrow in 1955. The most complete known fossils of S. progressus include cranial and postcranial elements currently all recorded in Tatarstan. These elements show that the animal is a rather medium-sized gorgonopsian.
Fairly complete remains listed in Tanzania have been attributed to a second species, S. parringtoni, which would make this genus the only known gorgonopsian to have lived in both Africa and Russia. However, it has been proven that this assimilation is mistaken, because is mainly based on superficial resemblances, leaving the latter awaiting a more in-depth study to determine the relationships with other representatives of the group. Moreover, the studies published since 2018 prove that S. progressus belongs to a grouping of Russian gorgonopsians, placed alongside the genera Suchogorgon , Pravoslavlevia and Inostrancevia, due to some shared cranial characteristics.
In 1938, the Soviet paleontologist Alexandra Paulinovna Hartmann-Weinberg described some fossil remains of gorgonopsians having been discovered in Tatarstan, in the present-day Russia. One of the fossils described in his paper is an incomplete but well-preserved skull, cataloged PIN 156/5. Hartmann-Weinberg considers this specimen to belong to a new species of the South African genus Arctognathus , designating it as Arctognathus progressus. The specific epithet progressus is incorrectly named due to its supposed morphological closeness to cynodonts, which have a large number of progressive and more mammal-like features than other gorgonopsians. [1] It quickly became apparent that the species is no more related to these same cynodonts than the other gorgonopsians, and in 1940, only two years after the publication of his article, one of Hartmann-Weinberg's employees, the reputed Ivan Yefremov reclassified the taxon as a new species of the Russian genus Inostrancevia , renaming it as Inostrancevia progressus. [2] In 1955, after the analysis of the material, Alexey Bystrow proposed a separate genus for the species, which he named Sauroctonus, and designates the specimen PIN 156/5 as the lectotype of the taxon [3] a proposal that will be quickly recognized later. [4] [5] [6] [2] [7] [8] [9] The genus name Sauroctonus comes from the Ancient Greek σαῦρος (saûros, "lizard") and κτόνος / (któnos, "murderer" or "killer"), to literally give "lizard killer", in reference to its carnivorous diet. [3] [10] All known specimens are from the type locality where the first known skull was discovered. Among these fossils remains figures PIN 156/6, a specimen containing a crushed skull, some anterior part of the postcranial skeleton and numerous isolated bones. [2] [10]
All confirmed remains of Sauroctonus are only recorded in Russian territory and belong to the species S. progressus, mainly represented by cranial material. [2] [10] [8] In 1950, a relatively complete skeleton, discovered in the Usili Formation in Tanzania, cataloged GPIT/RE/7113, was described by the German paleontologist Friedrich von Huene as a representative of the species Scymnognathus parringtoni, [lower-alpha 1] being named in honor of Francis Rex Parrington. [11] [10] In 1970, the skeleton was reidentified by the French paleontologist Denise Sigogneau-Russell as a specimen of Aelurognathus , being renamed Aelurognathus parringtoni. [4] It is from 2007 that the paleontologist Eva V. I. Gebauer reclassifies it as an African representative of the genus Sauroctonus, [6] a claim that she would confirm again in 2014. [7] However, this affiliation is formally rejected in 2018, as new classifications based on cranial anatomical traits show that derived gorgonopsians are separated into two clade of Russian and African origin, leaving GPIT/RE/7113 as an incertae sedis within the latter group. [8]
Other specimens have been attributed to this species, but no concrete affiliation has been worked out to date. For example, the well-preserved skull cataloged SAM-PK-K10034, mentioned briefly in a study concerning the noctural vision of non-mammalian synapsids, is referred to as S. cf. parringtoni. [12]
The skull size of Sauroctonus is 22.5 cm long, indicating that it should be a medium-sized gorgonopsian. The skull is narrow posteriorly with small orbits. The temporal fossa is elongated, the cranial arches are narrow, and the dentary bone is moderately high. [13] As in Viatkogorgon , Sauroctonus also has high palatal tuberosities that have many teeth, the bones poorly sculpted, and incisors only slightly larger than the postcanine teeth. [8] There are also 4 to 6 postcanine teeth on the maxillary bones. [14] [2]
The taxonomic position of Sauroctonus has changed many times over the decades. In 1974, the Russian paleontologist Leonid Petrovich Tatarinov classified Sauroctonus within the family Gorgonopsidae, and in the subfamily Cynariopinae, alongside various African genera such as Cynariops , Scylacognathus or Scylacops . [5] In a book published in 1989, Sigogneau-Russell leaves Sauroctonus as a gorgonopsian whose placement is undetermined. [13] Mikhail Ivakhnenko still classifies Sauroctonus within the Gorgonopsidae in 2003, without assigning it to any subtaxon. [14] In his 2007 thesis, Gebauer considers Sauroctonus to be a basal Gorgonopsidae. [6] These repetitive classification changes have left Sauroctonus in an uncertain position among the gorgonopsians, with some seeing it as close to the African genera, while others consider it to belong to a lineage in its own right. [8]
It is from 2018 that paleontologists Christian Kammerer and Vladimir Masyutin definitively reclassify Sauroctonus in a group of Russian gorgonopsians, alongside the genera Inostrancevia, Pravoslavlevia and Suchogorgon , in particular for certain shared cranial characteristics, more precisely for close contact between the pterygoid and the vomer. [8] This classification will be immediately followed by the next studies. [9] [15]
The following cladogram showing the position of Sauroctonus within Gorgonopsia follows Kammerer and Rubidge, 2022: [15]
Gorgonopsia |
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
One of the most recognizable features among gorgonopsians is the presence of long, saber-like canines on the upper and lower jaw. A study published in 2020 shows that several prehistoric predators with this comparable morphology would have had various possible prey-killing techniques. Among the gorgonopsians, Sauroctonus is found to have had a reduced jaw opening, unlike in the closely related Inostrancevia, indicating that it would not have been as specialized in hunting as the other representatives of the group. [16]
S. progressus is known from the locality of Sjomin Ravine, located in the republic of Tatarstan, in the northeast of European Russia. This fossil site, discovered in 1938 and dating from the end of the Middle Permian (Capitanian), is mainly represented by clays and silts with separated layers of fine polymictic sandstone, which contains fossils of tetrapods, represented by isolated bones and fragmentary skeletons, as well as rare flora remains. Apart from S. progressus, the main tetrapods identified in the area include the dicynodont therapsid Idelesaurus , the reptiliomorph Chroniosuchus , the temnospondyl Dvinosaurus , and even sauropsids, including the pareiasaur Scutosaurus and the archosauriform Eorasaurus . [17]
Gorgonopsia is an extinct clade of sabre-toothed therapsids from the Middle to Upper Permian roughly 265 to 252 million years ago. They are characterised by a long and narrow skull, as well as elongated upper and sometimes lower canine teeth and incisors which were likely used as slashing and stabbing weapons. Postcanine teeth are generally reduced or absent. For hunting large prey, they possibly used a bite-and-retreat tactic, ambushing and taking a debilitating bite out of the target, and following it at a safe distance before its injuries exhausted it, whereupon the gorgonopsian would grapple the animal and deliver a killing bite. They would have had an exorbitant gape, possibly in excess of 90°, without having to unhinge the jaw.
Gorgonops is an extinct genus of gorgonopsian therapsid, of which it is the type genus. Gorgonops lived during the Late Permian (Wuchiapingian), about 260–254 million years ago in what is now South Africa.
Inostrancevia is an extinct genus of large carnivorous therapsids which lived during the Late Permian in what is now European Russia and South Africa. The first-known fossils of this gorgonopsian were discovered in the Northern Dvina, where two almost complete skeletons were exhumed. Subsequently, several other fossil materials were discovered in various oblasts, and these finds will lead to a confusion about the exact number of valid species in the country, before only three of them were officially recognized: I. alexandri, I. latifrons and I. uralensis. More recent research carried out in South Africa has discovered fairly well-preserved remains of the genus, being attributed to the species I. africana. The whole genus is named in honor of Alexander Inostrantsev, professor of Vladimir P. Amalitsky, the paleontologist who described the taxon.
Lycaenops ("wolf-face") is a genus of carnivorous therapsids. It lived during the Middle Permian to the early Late Permian, about 260 mya, in what is now South Africa.
Dinogorgon is a genus of gorgonopsid from the Late Permian of South Africa and Tanzania. The generic name Dinogorgon is derived from Greek, meaning "terrible gorgon", while its species name rubidgei is taken from the surname of renowned Karoo paleontologist, Professor Bruce Rubidge, who has contributed to much of the research conducted on therapsids of the Karoo Basin. The type species of the genus is D. rubidgei.
Arctops is an extinct genus of gorgonopsian therapsids known from the Late Permian of South Africa. It measured up to 2 metres in length and its skull was 30 centimetres (12 in) long. The type species is Arctops willistoni. A second species, A. watsoni, may be synonymous with A. willistoni. A. kitchingi may be a third species of Arctops, but it was only tentatively assigned to the genus when it was first named. Both were formally synonymized with A. willistoni by Christian Kammerer in 2017.
Arctognathus is an extinct genus of gorgonopsids that throve during the Late Permian in the Karoo basin of what is now South Africa.
Aelurognathus is an extinct genus of gorgonopsian therapsids from the Permian of South Africa and Zambia.
Rubidgea is a genus of gorgonopsid from the upper Permian of South Africa and Tanzania, containing the species Rubidgea atrox. The generic name Rubidgea is sometimes believed to be derived from the surname of renowned Karoo paleontologist, Professor Bruce Rubidge, who has contributed to much of the research conducted on therapsids of the Karoo Basin. However, this generic name was actually erected in honor of Rubidge's paternal grandfather, Sydney Rubidge, who was a renowned fossil hunter. Its species name atrox is derived from Latin, meaning “fierce, savage, terrible”. Rubidgea is part of the gorgonopsian subfamily Rubidgeinae, a derived group of large-bodied gorgonopsians restricted to the Late Permian (Lopingian). The subfamily Rubidgeinae first appeared in the Tropidostoma Assemblage Zone. They reached their highest diversity in the Cistecephalus and Daptocephalus assemblage zones of the Beaufort Group in South Africa.
Cyonosaurus is a genus of gorgonopsian therapsids from the late Permian and possibly early Triassic of South Africa. Cyonosaurus was 0.6 to 1.1 metres in length, with a skull 9 to 18 centimetres in length. The type species Cyonosaurus longiceps was named in 1937.
Aloposaurus is an extinct genus of gorgonopsian therapsids from the Late Permian of South Africa. It was first named by Robert Broom in 1910, and contains the type species A. gracilis, and possibly a second species A. tenuis. This small gorgonopsid had a slender narrow skull only 12 centimetres (4.7 in) long, with a total body length of 60–70 cm (2.0–2.3 ft).
Aelurosaurus is a small, carnivorous, extinct genus of gorgonopsian therapsids from the Late Permian of South Africa. It was discovered in the Karoo Basin of South Africa, and first named by Richard Owen in 1881. It was named so because it appeared to be an ancestor for cat-like marsupials, but not yet a mammal itself. It contains five species, A. felinus, A. whaitsi, A. polyodon, A. wilmanae, and A.? watermeyeri. A. felinus, the type species, is generally well described with established features, while the other four species are not due to their poorly preserved holotypes.
Scylacops is an extinct genus of Gorgonopsia. It was first named by Broom in 1913, and contains two species, S. bigendens, and S. capensis. Its fossils have been found in South Africa and Zambia. It is believed to be closely related to the Gorgonopsian Sauroctonus progressus. Scylacops was a moderately sized Gorgonopsid.
Broomisaurus is an extinct genus of Gorgonopsia. It was first named by Joleaud in 1920, and contains the single species B. planiceps. Gebauer (2007) considered Broomisaurus to be a nomen dubium, indistinguishable as a separate taxon of gorgonopsian because it is based on only a fragmentary remains. A 2015 paper on Eriphostoma tentatively agreed with Gebauer's determination, but did not rule out the possibility that Broomisaurus might be synonymous with Eriphostoma.
Cerdorhinus is an extinct genus of gorgonopsian therapsids from the Permian of South Africa. The type species Cerdorhinus parvidens was named by South African paleontologist Robert Broom in 1936. A second species, Cerdorhinus rubidgei, was named in 1937. In 2007, a specimen of the latter was reassigned to the genus Cyonosaurus.
"Dixeya" nasuta is a species of the predatory gorgonopsian therapsids from the Late Permian of East Africa, known from fossils found in what is now Tanzania. The species has a complicated taxonomic history, it was originally named as a second species of the genus Dixeya which is now considered a junior synonym of Aelurognathus. "D." nasuta itself, however, was not moved to Aelurognathus, and although it was instead tentatively referred to Arctognathus at first it has since been recognised to not belong to this genus either. This situation leaves "Dixeya" nasuta without a formal genus name. It was proposed to belong to a new distinct genus, named "Njalila", that was informally proposed for the species in a PhD thesis, but this name has not yet been formally published and is currently a nomen nudum. "D." nasuta has been characterised from other gorgonopsians by a combination of its straight snout profile, upturned and 'pinched' nose, and curved jaw margin.
Cynodraco, also spelled Cynodracon or Cynodrakon, is a dubious genus of non-mammalian therapsid, probably gorgonopsian, from the late Permian of South Africa. Two species of the genus have been named, Cynodraco serridens and Cynodraco major. Its fossils have been found in the Cistecephalus Assemblage Zone, which dates to the Wuchiapingian age of the late Permian. Cynodraco was one of the first gorgonopsian taxa named, alongside Gorgonops and Lycosaurus, which were named in the same publication.
Leogorgon is an extinct genus of dubious therapsid from the Late Permian Sokolki Faunal Assemblage of Russia. It was originally classified as a rubidgeine gorgonopsian, and would have been the first member of that clade from outside of Africa if that identification had been valid. However, it may instead be a combination of the tooth of a gorgonopsian and the braincase of a dicynodont, and may be a wastebin taxon.
Nochnitsa is an extinct genus of gorgonopsian therapsids who lived during an uncertain stage of the Permian in what is now European Russia. Only one species is known, N. geminidens, described in 2018 from a single specimen including a complete skull and some postcranial remains, discovered in the red beds of Kotelnich, Kirov Oblast. The genus is named in reference to Nocnitsa, a nocturnal creature from Slavic mythology. This name is intended as a parallel to the Gorgons, which are named after many genera among gorgonopsians, as well as for the nocturnal behavior inferred for the animal. The only known specimen of Nochnitsa is one of the smallest gorgonopsians identified to date, with a skull measuring close to 8 cm (3.1 in) in length. The rare postcranial elements indicate that the animal's skeleton should be particularly slender.
Phorcys is an extinct genus of gorgonopsian that lived during the Middle Permian period (Guadalupian) of what is now South Africa. It is known from two specimens, both portions from the back of the skull, that were described and named in 2022 as a new genus and species P. dubei by Christian Kammerer and Bruce Rubidge. The generic name is from Phorcys of Greek mythology, the father of the Gorgons from which the gorgonopsians are named after, and refers to its status as one of the oldest representatives of the group in the fossil record. Phorcys was recovered from the lowest strata of the Tapinocephalus Assemblage Zone (AZ) of the Beaufort Group, making it one of the oldest known gorgonopsians in the fossil record—second only to fragmentary remains of an indeterminate gorgonopsian from the older underlying Eodicynodon Assemblage Zone.