Venyukovia

Last updated

Venyukovia
Temporal range: Middle Permian,
~267  Ma [1]
Ꞓ
O
S
D
C
P
T
J
K
Pg
N
↓
Venyukovia1DB.jpg
Speculative life restoration of Venyukovia
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade: Therapsida
Suborder:† Anomodontia
Infraorder:† Venyukovioidea
Genus:† Venyukovia
Amalitskii, 1922
Species:
†V. prima
Binomial name
†Venyukovia prima
Amalitskii, 1922

Venyukovia (named after its discoverer, Pavel N. Venyukov) is an extinct genus of venyukovioid therapsid, a basal anomodont from the Middle Permian of Russia. [1] The type and sole species, V. prima, is known only by a partial lower jaw with teeth. Venyukovia has often been incorrectly spelt as 'Venjukovia' in English literature. This stems from a spelling error made by Russian palaeontologist Ivan Efremov in 1940, who mistakenly replaced the 'y' with a 'j', which subsequently permeated through therapsid literature before the mistake was caught and corrected. [2] Venyukovia is the namesake for the Venyukovioidea, a group of small Russian basal anomodonts also including the closely related Otsheria , Suminia , Parasuminia and Ulemica , although it itself is also one of the poorest known. Like other venyukovioids, it had large projecting incisor-like teeth at the front and lacked canines, although the remaining teeth are simple compared to some other venyukovioids (e.g. Ulemica, Suminia), but may resemble those of Otsheria.

Contents

Description

Little can be said of the overall anatomy of Venyukovia beyond its mandibles and teeth. The partial jaw as preserved measures 52 mm long and is 18 mm high, including the crowns of the teeth. [3] Like other venyukovioids, Venyukovia has large procumbent incisor-like teeth at its jaw tips, possibly two on either side, superficially resembling the incisors of some mammals. There are no canines, and the remaining ten 'cheek' teeth (identified by Amalitskii as molars and premolars) are relatively simple in shape with pointed, laterally compressed crowns. [4] Ivakhnenko (1996) compared Venyukovia favourably to Otsheria, identifying a similar "shearing" dental apparatus between them compared to the more specialised jaws of Ulemica. [5] Like Otsheria, the 'cheek' teeth are bulbous and roughly as wide as they are long. [6]

Notably, Venyukovia appears to lack a lower dentary shelf, a bony structure on the lower jaws of the venyukovioids Ulemica and Suminia and the dicynodonts. This shelf was an attachment point for the powerful lateral adductor jaw muscle that allowed these anomodonts to chew, pulling the mandible backwards, and the absence of the lateral dentary shelf in Venyukovia suggests it may have also lacked this muscle, restricting its jaws to simple up-and-down motions. [7]

Discovery and naming

Pavel N. Venyukov, discoverer and namesake of Venyukovia Veniukov Pavel Nikolaevich (1858-1916).jpg
Pavel N. Venyukov, discoverer and namesake of Venyukovia

The only known fossil of Venyukovia was discovered in 1908 by Russian geologist Pavel Nikolaevich Venyukov, for whom it would later be formally named after in 1922. The specimen, now catalogued as PIN (Paleontological Institute) 48/1 was found by Venyukov isolated in a spoil heap of the Kargaly Mines of Orenburg. [8] The mines had excavated the copper-bearing sandstones of the southern Cis-Ural Mountains during the 18th and 19th centuries, and such Russian copper mines were of historical palaeontological significance for the discovery some of the first, albeit fragmentary fossils of Permian therapsids in the world. [9] [10] However, they had since shut down by the time Venyukovia was discovered, and the precise mining locality from where it was collected is unknown. [8] [11]

Venyukov brought his finds to Russian palaeontologist Vladimir P. Amalitskii (a.k.a. Amalitzky), and in a posthumous publication of his notes in 1922 were formally named and briefly described as Venyukovia prima. [8] Amalitskii described two specimens, a partial left mandible with the first right incisor attached (PIN 48/1) and a smaller specimen that he interpreted as the tip of a snout with teeth, later shown to be a mandibular symphysis. [3] [4] Notably, no type specimen of V. prima was given in this publication. This would not be amended until 1983 by Russian palaeontologist Peter Konstantinovich Chudinov who formally designated PIN 48/1 as the lectotype. [3] [8]

Amalitskii had not recognised Venyukovia as a non-mammalian synapsid, and instead had thought it was a triconodont mammal (similar to the first therapsid fossils from Russian copper mines, which were also initially mistaken for true mammals in 1838). [4] [9] The non-mammalian nature of Venyukovia was recognised by American palaeontologist George Gaylord Simpson just six years later in 1928, although he only regarded it as "clearly a reptile". [12] Venyukovia was later correctly shown to be a therapsid by Efremov in 1938, although he interpreted it as a dinocephalian. The true anomodont affinities of Venyukovia were not recognised until 1942 by the English palaeontologist D. M. S. Watson, who would later coin the infraorder Venyukovioidea for it and similar forms from Russia that had been discovered since then with American palaeontologist Alfred Romer in 1956. [13] [14]

Historically, numerous more complete skulls and jaws were referred to Venyukovia from Isheevo, Tatarstan and named as a second species (V. invisa) by Efremov in 1940. In 1983, Chudinov synonymised V. invisa with V. prima, however, in 1996 V. invisa and all its material were moved to their own genus entirely by Russian palaeontologist Mikhaïl Ivakhnenko, Ulemica. [3] [5] Consequently, much of what has been historically written about the morphology and functional anatomy of Venyukovia is actually based upon Ulemica (e.g. Barghusen (1976), King (1994)). [15] [16] In the same paper, Ivakhnenko commented on similarities between the type specimen of Venyukovia and Otsheria, highlighting that the jaw and dental anatomy of Venyukovia matches what would be expected from Otsheria, a venyukovioid known only by its skull, and has even regarded them as potential synonyms. [17] At the same time, Ivakhnenko also regarded the referred specimen PIN 48/2 as being more similar to Ulemica than Venyukovia. Thus, Venyukovia is now represented solely by the lecotype mandible. [5]

Classification

Venyukovia is a member of the infraorder Venyukovioidea, a clade of basal anomodonts related to dicynodonts. Anomodonts were a highly successful group of therapsids, largely represented by dicynodonts but also by a handful of basal genera. Venyukovia was one of the first such basal anomodonts to be discovered, although it was mistaken to be an early mammal at first by Amalitskii due to its mammal-like dentition. [4] Subsqeuent discoveries have since identified Venyukovia as part of a radiation of basal anomodonts in Eastern Europe for which it is now the namesake, the Venyukovioidea. Venyukovia has additionally also been variously assigned both family-level and subfamily-level ranked groups, the Venyukoviidae and Venyukoviinae. Despite being the group's namesake, it is unclear how Venyukovia is related to other venyukovioids and so these subgroups cannot be reliably defined. This is largely due to the incompleteness of Venyukovia itself, and as such it has not been included in any phylogenetic analyses of basal anomodonts due to the low number of characteristics that can be scored for it in one. [2] [7]

Palaeoenvironment

Although found across various individual mines and mixed in spoil heaps, the fossil flora and fauna of the Kargaly Mines can be recognised as a fossil assemblage. Namely, they have been correlated to the better known Ocher Assemblage Zone to the East. The Kargaly Mines have produced a diverse array of tetrapod, fish, invertebrate (including bivalves, conchostracans, and insects) and plant fossils, although due to their often fragmentary nature specific identifications are uncertain. [8]

Apart from Venyukovia, other therapsids are mostly represented by dinocephalians, including the dubious predatory anteosaur Admetophoneus (possibly a synonym of Titanophoneus ) and potentially Syodon (though it is uncertain the referred specimen comes from these deposits), as well as the tapinocephalians Deuterosaurus jubilaei and Ulemosaurus , although fragmentary remains of therocephalians have been identified. [18] Other tetrapods include, Chalcosaurus (a lanthanosuchoid parareptile), early tetrapods such as the seymouriamorph Discosauriscus netschajevi and an unidentified gephyrostegid, while temnospondyls are known by the archegosauroid Platyoposaurus . [8]

Numerous fossils from a wide variety of plants have also been discovered in the copper sandstones of the Kargaly Mines. These include spore-bearing plants like lycopods, horsetails such as Paracalamites , a Phyllotheca -like species, and trunks of the tree-like Calamites , as well as indeterminate ferns. Seed ferns are represented mostly by peltaspermaceans, including pinnate Permocallipteris and monopinnate Compsopteris leaf fronds, whereas the angaropeltacean Phylladoderma is rarer. Ginkgophytes are represented by the leaves Psygmophyllum , Kerpia , and Baiera , while conifers are known by Tylodendron shoots, Steirophyllum , and Cordaicarpus seeds. [8]

From the sedimentology of the deposits, the locality has been interpreted as being located near the foothills of the Paleo-Urals, with abundant vegetation growing around high-energy streams with heavy run-off from the western slopes of mountains. The forests were dominated by conifers and ginkgophytes, with an undergrowth of ferns and seed ferns and horsetails along the riverbanks. [8]

Related Research Articles

<span class="mw-page-title-main">Dicynodontia</span> Extinct clade of therapsids

Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivores that typically bore a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typically toothless beak, unique amongst all synapsids. Dicynodonts first appeared in Southern Pangaea during the mid-Permian, ca. 270–260 million years ago, and became globally distributed and the dominant herbivorous animals in the Late Permian, ca. 260–252 Mya. They were devastated by the end-Permian Extinction that wiped out most other therapsids ca. 252 Mya. They rebounded during the Triassic but died out towards the end of that period. They were the most successful and diverse of the non-mammalian therapsids, with over 70 genera known, varying from rat-sized burrowers to elephant-sized browsers.

<span class="mw-page-title-main">Dinocephalia</span> Extinct clade of stem-mammals

Dinocephalians 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. Dinocephalians included herbivorous, carnivorous, and omnivorous forms. Many species had thickened skulls with many knobs and bony projections. Dinocephalians were the first non-mammalian therapsids to be scientifically described and their fossils are known from Russia, China, Brazil, South Africa, Zimbabwe, and Tanzania.

<span class="mw-page-title-main">Anomodontia</span> Suborder of stem-mammals

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. Anomodonts were very diverse during the Middle Permian, including primitive forms like Anomocephalus and Patranomodon and groups like Venyukovioidea and Dromasauria. Dicynodonts became the most successful and abundant of all herbivores in the Late Permian, filling ecological niches ranging from large browsers down to small burrowers. Few dicynodont families survived the Permian–Triassic extinction event, but one lineage (Kannemeyeriiformes) evolved into large, stocky forms that became dominant terrestrial herbivores right until the Late Triassic, when changing conditions caused them to decline, finally going extinct during the Triassic–Jurassic extinction event.

<span class="mw-page-title-main">Gorgonopsia</span> Extinct group of saber-toothed therapsids from the Permian

Gorgonopsia is an extinct clade of sabre-toothed therapsids from the Middle to the Upper Permian, possibly even up to the Early Triassic, roughly between 265 and 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.

<i>Suminia</i> Extinct genus of therapsids

Suminia is an extinct genus of basal anomodont that lived during the Tatarian age of the late Permian, spanning approximately from 268-252 Ma. Suminia is recognized the youngest non-dicynodont anomodont. Its fossil localities are primarily derived from the Kotel’nich locality of the Kirov Oblast in Russia. However, there have been some isolated specimen found in a few different localities, all from eastern European regions of Russia.

<i>Biarmosuchus</i> Extinct genus of therapsids

Biarmosuchus is an extinct genus of biarmosuchian therapsids that lived around 267 mya during the Middle Permian period. Biarmosuchus was discovered in the Perm region of Russia. The first specimen was found in channel sandstone that was deposited by flood waters originating from the young Ural Mountains.

<i>Diictodon</i> Extinct genus of dicynodonts

Diictodon is an extinct genus of pylaecephalid dicynodont that lived during the Late Permian period, approximately 255 million years ago. Fossils have been found in the Cistecephalus Assemblage Zone of the Madumabisa Mudstone of the Luangwa Basin in Zambia and the Tropidostoma Assemblage Zone of the Teekloof Formation, Tapinocephalus Assemblage Zone of the Abrahamskraal Formation, Dicynodon Assemblage Zone of the Balfour Formation, Cistecephalus Assemblage Zone of the Middleton or Balfour Formation of South Africa and the Guodikeng Formation of China. Roughly half of all Permian vertebrate specimens found in South Africa are those of Diictodon. This small herbivorous animal was one of the most successful synapsids in the Permian period.

<i>Inostrancevia</i> Extinct genus of therapsids

Inostrancevia is an extinct genus of large carnivorous therapsids which lived during the Late Permian in what is now European Russia and Southern 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. An isolated left premaxilla suggests that Inostrancevia also lived in Tanzania during the earliest Lopingian age. The whole genus is named in honor of Alexander Inostrantsev, professor of Vladimir P. Amalitsky, the paleontologist who described the taxon.

<i>Otsheria</i> Extinct genus of therapsids

Otsheria is an extinct genus of anomodont, in the infraorder venyukovioidea. It lived in modern-day Russia during the Permian.

<i>Biseridens</i> Extinct genus of therapsids

Biseridens is an extinct genus of anomodont therapsid, and one of the most basal anomodont genera known. Originally known from a partial skull misidentified as an eotitanosuchian in 1997, another well-preserved skull was found in the Qingtoushan Formation in the Qilian Mountains of Gansu, China, in 2009 that clarified its relationships to anomodonts, such as the dicynodonts.

<i>Dimacrodon</i> Extinct genus of synapsids

Dimacrodon is an extinct genus of non-mammalian synapsid from the latest Early Permian San Angelo Formation of Texas. It is distinguished by toothless, possibly beaked jaw tips, large lower canines and a thin bony crest on top of its head. Previously thought to be an anomodont therapsid related to dicynodonts, it was later found to lack any diagnostic features of anomodonts or even therapsids and instead appears to be a 'pelycosaur'-grade synapsid of uncertain classification.

<i>Niaftasuchus</i> Extinct genus of therapsids

Niaftasuchus is an extinct genus of therapsids. Its type and only named species is Niaftasuchus zekkeli.

<i>Ulemica</i> Extinct genus of therapsids

Ulemica is an extinct genus of venyukovioid therapsids, a type of anomodont related to dicynodonts. It lived during the Middle Permian period in what is now Russia, and is known from the Isheevo assemblage of the Amanakskaya Formation. The type species, U. invisa, was originally placed in the genus Venyukovia by Russian palaeontologist Ivan Efremov in 1940. It was later given its own genus Ulemica in 1996 by Mikhaïl Ivakhnenko, who also named a second species U. efremovi. Efremov had originally intended to name the fossils of U. invisa as 'Myctosuchus invisus', however, he later recognised their similarity to Venyukovia and chose to assign the Isheevo material to this genus and leaving 'Myctosuchus' a nomen nudum.

<span class="mw-page-title-main">Venyukovioidea</span> Extinct infraorder of therapsids

Venyukovioidea is an infraorder of anomodont therapsids related to dicynodonts from the Permian of Russia. They have also been known as 'Venjukovioidea', as well as by the similar names 'Venyukoviamorpha' or 'Venjukoviamorpha' in literature. This in part owes to a misspelling by Russian palaeontologist Ivan Efremov in 1940 when he mistakenly spelt Venyukovia, the namesake of the group, with a 'j' instead of a 'y', which permeated through subsequent therapsid literature before the mistake was caught and corrected. The order Ulemicia has also been coined for a similar taxonomic concept in Russian scientific literature, which notably excludes Suminia and Parasuminia.

<span class="mw-page-title-main">Chainosauria</span> Extinct clade of therapsids

Chainosauria is a large and speciose clade of anomodont therapsid that includes the highly diverse dicynodonts and a small number of closely related basal genera —although the total composition and taxonomic scope of Chainosauria is in flux. Chainosauria was named in 1923 to group together the dicynodonts and their close relatives, namely three small anomodont genera from South Africa that made up the now defunct group 'Dromasauria'. The name soon fell into disuse, however, as it was functionally replaced by Anomodontia. Chainosauria was later revived cladistically in 2009, preserving the association of dicynodonts and the 'dromasaurs' and has since served in effect as both a cladistic and a biogeographic counterpart to the Laurasian venyukovioids, with early chainosaurs appearing to have been a Gondwanan radiation.

<i>Karenites</i> Genus of therapsids from the Late Permian of Russia

Karenites is an extinct genus of therocephalian therapsids from the Late Permian of Russia. The only species is Karenites ornamentatus, named in 1995. Several fossil specimens are known from the town of Kotelnich in Kirov Oblast.

<span class="mw-page-title-main">Anomocephaloidea</span> Extinct clade of therapsids

Anomocephaloidea is a clade of basal anomodont therapsids related to the dicynodonts known from what is now South Africa and Brazil during the Middle Permian. It includes only two species, Anomocephalus africanus from the Karoo Basin of South Africa and Tiarajudens eccentricus from the Paraná Basin of Brazil. Anomocephaloidea was named in 2011 with the discovery of Tiarajudens, although Anomocephalus itself has been known since 1999.

Parasumina is an extinct genus of anomodont known from the late Capitanian age at the end of the middle Permian period of European Russia. The type and only species is Parasuminia ivakhnenkoi. It was closely related to Suminia, another Russian anomodont, and was named for its resemblance. Little is known about Parasuminia as the only fossils are of fragmentary pieces of the skull and jaw, but the known remains suggest that its head and jaws were deeper and more robust than those of Suminia, and with shorter, stouter teeth. However, despite these differences they appear to have been similar animals with a similarly complex method of processing vegetation.

Taoheodon is an extinct genus of dicynodont therapsid from the Sunjiagou Formation in the Shanxi province of China, dated to the Wuchiapingian age of the Late Permian. Its type and only known species is T. baizhijuni. Taoheodon was a close relative of the well known Dicynodon, and may represent a biogeographical link between the South African Dicynodon and similar dicynodonts found in Laos.

<i>Nyaphulia</i> Extinct genus of dicynodonts

Nyaphulia is an extinct genus of dicynodont therapsid from the middle Permian of South Africa, containing only the type species N. oelofseni. The generic name is in honour of John Nyaphuli of the National Museum of Bloemfontein, who contributed extensively to South African palaeontology and discovered the holotype specimen of Nyaphulia in 1982. Nyaphulia was initially named as a second species of the basal dicynodont Eodicynodon by Professor Bruce Rubidge in 1990 as E. oelofseni, named after his mentor in palaeontology and geology Dr. Burger Oelofsen.

References

  1. 1 2 Olroyd, S. L.; Sidor, C. A. (2017). "A review of the Guadalupian (middle Permian) global tetrapod fossil record". Earth-Science Reviews. 171: 583–597. Bibcode:2017ESRv..171..583O. doi: 10.1016/j.earscirev.2017.07.001 .
  2. 1 2 Kammerer, C.F.; Angielczyk, K.D. (2009). "A proposed higher taxonomy of anomodont therapsids" (PDF). Zootaxa. 2018: 1–24. doi:10.11646/ZOOTAXA.2018.1.1.
  3. 1 2 3 4 Chudinov, P. K. (1983). "Early Therapsids" (PDF). Proceedings of the Paleontological Institute (in Russian). 202: 67–70.
  4. 1 2 3 4 Amalitskii, V. P. (1922). "Diagnoses of the new forms of vertebrates and plants from the upper Permian of North Dvina" (PDF). Bulletin of the Russian Academy of Sciences. 16 (6). Saint Petersburg: 329–340.
  5. 1 2 3 Ivakhnenko, M. F. (1996). "Primitive anomodonts, venyukoviids, from the Late Permian of Eastern Europe". Paleontological Journal. 30: 575–582.
  6. ↑ Ivakhnenko, M. F. (2008). "The Subclass Theromorpha". In Ivakhnenko, M. F.; Kurochkin, E. N. (eds.). Iskopaemye pozvonochnye Rossii i sopredel'nykh stran. Iskopaemye reptilii i ptitsy. Chast' 1 (Fossil Vertebrates of Russia and Adjacent Countries: Extinct Reptiles and Birds: Part 1) (in Russian). Moscow: GEOS. p. 158.
  7. 1 2 Angielczyk, K. D. (2004). "Phylogenetic evidence for and implications of a dual origin of propaliny in anomodont therapsids (Synapsida)". Paleobiology. 30 (2): 268–296. doi:10.1666/0094-8373(2004)030<0268:PEFAIO>2.0.CO;2. S2CID   86147610.
  8. 1 2 3 4 5 6 7 8 Naugolnykha, S. V.; Ivanovb, A. V.; Uliakhind, A. V.; Novikovd, I. V. (2022). "Paleoecological and Depositional Environment of Permian Copper-Bearing Sandstone Fossil Plants and Tetrapod Localities: Records from Bashkortostan and Kargalka River Basin, Orenburg Region, Russia". Paleontological Journal. 56 (11): 1538–1555. doi:10.1134/S0031030122110120. S2CID   256618393.
  9. 1 2 Kammerer, C. F. (2011). "Systematics of the Anteosauria (Therapsida: Dinocephalia)". Journal of Systematic Palaeontology. 9 (2): 261–304. doi:10.1080/14772019.2010.492645. S2CID   84799772.
  10. ↑ Angielczyk, Kenneth D.; Kammerer, Christian F. (2018). "Non-Mammalian synapsids: the deep roots of the mammalian family tree". In Zachos, Frank E.; Asher, Robert J. (eds.). Mammalian Evolution, Diversity and Systematics. Berlin: De Gruyter. p. 151. ISBN   9783110275902.
  11. ↑ Ochev, V. G.; Surkov, M. V. (2000). "The history of excavation of Permo-Triassic vertebrates from Eastern Europe". In Benton, M. J.; Shishkin, M. A.; Unwin, D. M. (eds.). The Age of Dinosaurs in Russia and Mongolia. Cambridge University Press. pp. 1–16. ISBN   978-0-521-54582-2.
  12. ↑ Simpson, G. G. (1928). "Mesozoic mammals, X; Some Triassic mammals". American Journal of Science. s5-15 (86): 154–167. Bibcode:1928AmJS...15..154S. doi:10.2475/ajs.s5-15.86.154.
  13. ↑ Watson, D. M. S. (1942). "On Permian and Triassic tetrapods". Geological Magazine. 79 (2): 81–116. Bibcode:1942GeoM...79...81W. doi:10.1017/S0016756800073593. S2CID   131417438.
  14. ↑ Watson, D. M. S.; Romer, A. S. (1956). "A classification of therapsid reptiles". Bulletin of the Museum of Comparative Zoology. 114 (2): 37–89.
  15. ↑ Barghusen, H. R. (1976). "Notes on the adductor jaw musculature of Venjukovia, a primitive anomodont therapsid from the Permian of the USSR". Annals of the South African Museum. 69 (10): 249–260. ISBN   0949940933.
  16. ↑ King, G. M. (1994). "The early anomodont Venjukovia and the evolution of the anomodont skull". Journal of Zoology. 232 (4): 651–673. doi:10.1111/j.1469-7998.1994.tb04620.x.
  17. ↑ Ivakhnenko, M. F. (2008). "Cranial morphology and evolution of Permian Dinomorpha (Eotherapsida) of eastern Europe". Paleontological Journal. 42 (9): 859–995. doi:10.1134/S0031030108090013. S2CID   85114195.
  18. ↑ Olson, E. C. (1957). "Catalogue of localities of Permian and Triassic terrestrial vertebrates of the territories of the USSR". The Journal of Geology. 65 (2): 196–226. Bibcode:1957JG.....65..196O. doi:10.1086/626422. S2CID   129180659.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.