Lystrosaurus

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Lystrosaurus
Temporal range: Late Permian (Lopingian)–Early Triassic (Olenekian), 255–248  Ma
Lystrosaurus hedini IMG 4469.jpg
L. hedini skeletal mount from the Natural history museum of Zürich
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Clade: Therapsida
Suborder:† Anomodontia
Clade:† Dicynodontia
Family:† Lystrosauridae
Genus:† Lystrosaurus
Cope, 1870
Species
List
  • L. murrayi(Huxley, 1859) (type)
  • L. declivis(Owen, 1860)
  • L. curvatus(Owen, 1876)
  • L. maccaigi Seeley, 1898

Lystrosaurus ( /ˌlɪstroʊˈsɔːrəs/ ; 'shovel lizard'; proper Ancient Greek is λίστρονlístron ‘tool for leveling or smoothing, shovel, spade, hoe’) is an extinct genus of herbivorous dicynodont therapsids from the late Permian and Early Triassic epochs (around 248 million years ago). It lived in what is now Antarctica, India, China, Mongolia, European Russia and South Africa. Four to six species are currently recognized, although from the 1930s to 1970s the number of species was thought to be much higher. They ranged in size from that of a small dog to 8 feet (2.5 meters) long. [1]

Contents

As a dicynodont, Lystrosaurus had only two teeth (a pair of tusk-like canines), and is thought to have had a horny beak that was used for biting off pieces of vegetation. Lystrosaurus was a heavily built, herbivorous animal. The structure of its shoulders and hip joints suggests that Lystrosaurus moved with a semi-sprawling gait. The forelimbs were even more robust than the hindlimbs, and the animal is thought to have been a powerful digger that nested in burrows.

Lystrosaurus survived the Permian-Triassic extinction, 252 million years ago. In the Early Triassic, they were by far the most common terrestrial vertebrates, accounting for as many as 95% of the total individuals in some fossil beds. [2] Researchers have offered various hypotheses for why Lystrosaurus survived the extinction event and thrived in the early Triassic.

History of discovery

Map of Pangea showing locations of Lystrosaurus remains as yellow disks. Distorted boundaries of modern continents shown as grey lines. (Distributions for lystrosaurs and three other Permian and Triassic fossil groups used as biogeographic evidence for continental drift and certain land bridges.) Wegener fossils-mapped.png
Map of Pangea showing locations of Lystrosaurus remains as yellow disks. Distorted boundaries of modern continents shown as grey lines. (Distributions for lystrosaurs and three other Permian and Triassic fossil groups used as biogeographic evidence for continental drift and certain land bridges.)

Dr. Elias Root Beadle, a Philadelphia missionary and avid fossil collector, discovered the first Lystrosaurus skull. Beadle wrote to the eminent paleontologist Othniel Charles Marsh, but received no reply. Marsh's rival, Edward Drinker Cope, was very interested in seeing the find, and described and named Lystrosaurus in the Proceedings of the American Philosophical Society in 1870. [3] Its name is derived from the Ancient Greek words listron, "shovel", and sauros, "lizard". [4] Marsh belatedly purchased the skull in May 1871, although his interest in an already-described specimen was unclear; he may have wanted to carefully scrutinize Cope's description and illustration. [3]

Plate tectonics

The discovery of Lystrosaurus fossils at Coalsack Bluff in the Transantarctic Mountains by Edwin H. Colbert and his team in 1969–1970 helped support the hypothesis of plate tectonics and strengthen the theory, since Lystrosaurus had already been found in the lower Triassic of southern Africa as well as in India and China. [5] [6]

Distribution and species

Lystrosaurus fossils have been found in many Late Permian and Early Triassic terrestrial bone beds, most abundantly in Africa, and to a lesser extent in parts of what are now India, China, Mongolia, European Russia, and Antarctica (which was not over the South Pole at the time). [7]

Species found in Africa

L. murrayi skeleton Lystrosaurus murrayi 7.JPG
L. murrayi skeleton

Most Lystrosaurus fossils have been found in the Balfour and Katberg Formations of the Karoo basin in South Africa; these specimens offer the best prospects of identifying species because they are the most numerous and have been studied for the longest time. As so often with fossils, there is debate in the paleontological community as to exactly how many species have been found in the Karoo basin. Studies from the 1930s to 1970s suggested a large number (23 in one case). [8] However, by the 1980s and 1990s, only 6 species were recognized in the Karoo: L. curvatus, L. platyceps, L. oviceps, L. maccaigi, L. murrayi, and L. declivis. A study in 2011 reduced that number to four, treating the fossils previously labeled as L. platyceps and L. oviceps as members of L. curvatus. [9]

L. maccaigi is the largest and apparently most specialized species, while L. curvatus was the least specialized. A Lystrosaurus-like fossil, Kwazulusaurus shakai, has also been found in South Africa. Although not assigned to the same genus, K. shakai is very similar to L. curvatus. Some paleontologists have therefore proposed that K. shakai was possibly an ancestor of or closely related to the ancestors of L. curvatus, while L. maccaigi arose from a different lineage. [8] L. maccaigi is found only in sediments from the Permian period, and apparently did not survive the Permian–Triassic extinction event. Its specialized features and sudden appearance in the fossil record without an obvious ancestor may indicate that it immigrated into the Karoo from an area in which Late Permian sediments have not been found. [8] L. curvatus is found in a relatively narrow band of sediments from shortly before and after the extinction, and can be used as an approximate marker for the boundary between the Permian and Triassic periods. A skull identified as L. curvatus has been found in late Permian sediments from Zambia. For many years it had been thought that there were no Permian specimens of L. curvatus in the Karoo, which led to suggestions that L. curvatus immigrated from Zambia into the Karoo. However, a re-examination of Permian specimens in the Karoo has identified some as L. curvatus, and there is no need to assume immigration. [8]

L. murrayi and L. declivis are found only in Triassic sediments. [8]

Other species

Lystrosaurus georgi fossils have been found in the Earliest Triassic sediments of the Moscow Basin in Russia. It was probably closely related to the African Lystrosaurus curvatus, [7] which is regarded as one of the least specialized species and has been found in very Late Permian and very Early Triassic sediments. [8]

L. murrayi, in addition to two undescribed species presently assigned to L. curvatus and L. declivis, is known from the Early Triassic Panchet Formation of the Damodar Valley and the Kamthi Formation of the Pranhita-Godavari Basin in India. [10] Seven Lystrosaurus species have been described from the Early Triassic Jiucaiyuan, Guodikeng and Wutonggou formations of the Bogda Mountains in Xinjiang, China, although it is possible that only two (L. youngi and L. hedini) are valid; unusually, no Chinese Lystrosaurus specimens are known below the Permian-Triassic boundary in this region. [11] [12] L. curvatus, L. murrayi, and L. maccaigi are known from the Fremouw Formation in the Transantarctic Mountains of Antarctica. [13]

Description

Size of Lystrosaurus murrayi relative to a human. Lystrosaurus murrayi scale.svg
Size of Lystrosaurus murrayi relative to a human.

Lystrosaurus was a dicynodont therapsid, between 0.6 to 2.5 m (2 to 8 ft) long with an average of about 0.9 m (3 ft) depending upon the species. [14]

Unlike other therapsids, dicynodonts had very short snouts and no teeth except for the tusk-like upper canines. Dicynodonts are generally thought to have had horny beaks like those of turtles, for shearing off pieces of vegetation, which were then ground on a horny secondary palate when the mouth was shut. The jaw joint was weak and moved backwards and forwards with a shearing action, instead of the more common sideways or up and down movements. It is thought that the jaw muscles were attached unusually far forward on the skull and took up a lot of space on the top and back of the skull. As a result, the eyes were set high and well forward on the skull, and the face was short. [15]

Features of the skeleton indicate that Lystrosaurus moved with a semi-sprawling gait. The lower rear corner of the scapula (shoulder blade) was strongly ossified (built of strong bone), which suggests that movement of the scapula contributed to the stride length of the forelimbs and reduced the sideways flexing of the body. [7] The five sacral vertebrae were massive but not fused to each other and to the pelvis, making the back more rigid and reducing sideways flexing while the animal was walking. Therapsids with fewer than five sacral vertebrae are thought to have had sprawling limbs, like those of modern lizards. [7] In dinosaurs and mammals, which have erect limbs, the sacral vertebrae are fused to each other and to the pelvis. [16] A buttress above each acetabulum (hip socket) is thought to have prevented dislocation of the femur (thigh bone) while Lystrosaurus was walking with a semi-sprawling gait. [7] The forelimbs of Lystrosaurus were massive, [7] and Lystrosaurus is thought to have been a powerful burrower.

Mummified specimens recovered from the Karoo Basin and described in 2022 revealed that Lystrosaurus had dimpled, leathery, and hairless skin. [17] [18]

Paleoecology

Dominance of the Early Triassic

Lystrosaurus georgi Lystr georg1DB.jpg
Lystrosaurus georgi

Lystrosaurus is notable for dominating southern Pangaea for millions of years during the Early Triassic. At least one unidentified species of this genus survived the end-Permian mass extinction and, in the absence of predators and herbivorous competitors, went on to thrive and re-radiate into a number of species within the genus, [19] becoming the most common group of terrestrial vertebrates during the Early Triassic; for a while, 95% of land vertebrates were Lystrosaurus. [19] [20] This is the only time that a single species or genus of land animal dominated the Earth to such a degree. [21] A few other Permian therapsid genera also survived the mass extinction and appear in Triassic rocks—the therocephalians Tetracynodon , Moschorhinus , Ictidosuchoides and Promoschorhynchus —but do not appear to have been abundant in the Triassic; [8] [22] complete ecological recovery took 30 million years, spanning the Early and Middle Triassic. [23]

Several attempts have been made to explain why Lystrosaurus survived the Permian–Triassic extinction event, the "mother of all mass extinctions", [24] and why it dominated Early Triassic fauna to such an unprecedented extent:

Lystrosaurus murrayi Lystr murr1DB.jpg
Lystrosaurus murrayi
Lystrosaurus skeletal diagram Lystrosaurus skeleton.jpg
Lystrosaurus skeletal diagram

See also

Related Research Articles

<span class="mw-page-title-main">Therapsida</span> Clade of tetrapods including mammals

Therapsida is a clade comprising a major group of eupelycosaurian synapsids that includes mammals and their ancestors and close relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more underneath the body, resulting in a more "standing" quadrupedal posture, as opposed to the lower sprawling posture of many reptiles and amphibians.

<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 80-90 genera known, varying from rat-sized burrowers to elephant-sized browsers.

<i>Cistecephalus</i> Assemblage Zone

The Cistecephalus Assemblage Zone is a tetrapod assemblage zone or biozone found in the Adelaide Subgroup of the Beaufort Group, a majorly fossiliferous and geologically important geological group of the Karoo Supergroup in South Africa. This biozone has outcrops located in the Teekloof Formation north-west of Beaufort West in the Western Cape, in the upper Middleton and lower Balfour Formations respectively from Colesberg of the Northern Cape to east of Graaff-Reinet in the Eastern Cape. The Cistecephalus Assemblage Zone is one of eight biozones found in the Beaufort Group, and is considered to be Late Permian in age.

<i>Daptocephalus</i> Assemblage Zone Biozone of fossils

The Daptocephalus Assemblage Zone is a tetrapod assemblage zone or biozone found in the Adelaide Subgroup of the Beaufort Group, a majorly fossiliferous and geologically important Group of the Karoo Supergroup in South Africa. This biozone has outcrops located in the upper Teekloof Formation west of 24°E, the majority of the Balfour Formation east of 24°E, and the Normandien Formation in the north. It has numerous localities which are spread out from Colesberg in the Northern Cape, Graaff-Reniet to Mthatha in the Eastern Cape, and from Bloemfontein to Harrismith in the Free State. The Daptocephalus Assemblage Zone is one of eight biozones found in the Beaufort Group and is considered Late Permian (Lopingian) in age. Its contact with the overlying Lystrosaurus Assemblage Zone marks the Permian-Triassic boundary.

<i>Lystrosaurus</i> Assemblage Zone

The Lystrosaurus Assemblage Zone is a tetrapod assemblage zone or biozone which correlates to the upper Adelaide and lower Tarkastad Subgroups of the Beaufort Group, a fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. This biozone has outcrops in the south central Eastern Cape and in the southern and northeastern Free State. The Lystrosaurus Assemblage Zone is one of eight biozones found in the Beaufort Group, and is considered to be Early Triassic in age.

<i>Moschorhinus</i> Genus of synapsid from late Permian and early Triassic South Africa

Moschorhinus is an extinct genus of therocephalian synapsid in the family Akidnognathidae with only one species: M. kitchingi, which has been found in the Late Permian to Early Triassic of the South African Karoo Supergroup. It was a large carnivorous therapsid, reaching 1.1–1.5 metres (3.6–4.9 ft) in total body length with the largest skull comparable to that of a lion in size, and had a broad, blunt snout which bore long, straight canines.

<i>Tetracynodon</i> Extinct genus of therapsids from Early Triassic South Africa

Tetracynodon is an extinct genus of therocephalian. Fossils of Tetracynodon have been found in the Karoo Basin of South Africa. Two species are known: the type species T. tenuis from the Late Permian and the species T. darti from the Early Triassic. Both species were small-bodied and probably fed on insects and small vertebrates. Although Tetracynodon is more closely related to mammals than to reptiles, its braincase is very primitive and more resembles that of modern amphibians and reptiles than of mammals.

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

Paraburnetia is an extinct genus of biarmosuchian therapsids from the Late Permian of South Africa. It is known for its species P. sneeubergensis and belongs to the family Burnetiidae. Paraburnetia lived just before the Permian–Triassic mass extinction event.

<i>Myosaurus</i> Extinct genus of dicynodont from the lower Triassic

Myosaurus is a genus of dicynodont synapsids. Myosaurus was a small, herbivorous synapsid that existed around the early Triassic period. All of the fossils found of this species were found in Antarctica and South Africa. Compared to other fossils found from species that existed during this time, the Myosaurus is not common in the fossil record. This is due to a shortage of discovered fossils that possess characteristics unique to the Myosaurus. Notably, under 130 fossil fragments have been found that have been classified as Myosauridae, and almost all have been skulls. These skulls can be classified as Myosaurus because this species, unlike other dicynodonts, do not possess tusks or postfrontal teeth. The only species identified in the family Myosauridae is the Myosaurus gracilis, or M. gracilis. It should be recognized that the Myosaurus is almost always referred to as the M. gracilis in scientific research.

<i>Broomistega</i> Extinct genus of temnospondyl from the early Triassic

Broomistega is an extinct genus of temnospondyl in the family Rhinesuchidae. It is known from one species, Broomistega putterilli, which was renamed in 2000 from Lydekkerina putterilli Broom 1930. Fossils are known from the Early Triassic Lystrosaurus Assemblage Zone of the Beaufort Group in the Karoo Basin of present-day South Africa, a region that had been an enclave of Gondwana. Specimens of B. putterilli were once thought to represent young individuals of another larger rhinesuchid such as Uranocentrodon, but the species is now regarded as a paedomorphic taxon, possessing the features of juvenile rhinesuchids into adulthood.

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

Dicynodontoides is a genus of small to medium-bodied, herbivorous, emydopoid dicynodonts from the Late Permian. The name Dicynodontoides references its “dicynodont-like” appearance due to the caniniform tusks featured by most members of this infraorder. Kingoria, a junior synonym, has been used more widely in the literature than the more obscure Dicynodontoides, which is similar-sounding to another distantly related genus of dicynodont, Dicynodon. Two species are recognized: D. recurvidens from South Africa, and D. nowacki from Tanzania.

<i>Progalesaurus</i> Extinct genus of cynodonts

Progalesaurus is an extinct genus of galesaurid cynodont from the early Triassic. Progalesaurus is known from a single fossil of the species Progalesaurus lootsbergensis, found in the Lystrosaurus Assemblage Zone of the Balfour Formation. Close relatives of Progalesaurus, other galesaurids, include Galesaurus and Cynosaurus. Galesaurids appeared just before the Permian-Triassic extinction event, and disappeared from the fossil record in the Middle-Triassic.

Platycraniellus is an extinct genus of carnivorous cynodonts from the Early Triassic. It is known from the Lystrosaurus Assemblage Zone of the Normandien Formation in South Africa. P. elegans is the only species in this genus based on the holotype specimen from the Ditsong National Museum of Natural History in Pretoria, South Africa. Due to limited fossil records for study, Platycraniellus has only been briefly described a handful of times.

<i>Langbergia</i> Extinct genus of cynodonts

Langbergia is an extinct genus of trirachodontid cynodont from the Early Triassic of South Africa. The type and only species L. modisei was named in 2006 after the farm where the holotype was found, Langberg 566. Langbergia was found in the Burgersdorp Formation in the Beaufort Group, a part of the Cynognathus Assemblage Zone. The closely related trirachodontids Trirachodon and Cricodon were found in the same area.

<i>Manubrantlia</i> Extinct genus of temnospondyls

Manubrantlia was a genus of lapillopsid temnospondyls from the Early Triassic Panchet Formation of India. This genus is only known from a single holotype left jaw, given the designation ISI A 57. Despite the paucity of remains, the jaw is still identifiable as belonging to a relative of Lapillopsis. For example, all three of its coronoid bones possessed teeth, the articular bone is partially visible in lateral (outer) view, and its postsplenial does not contact the posterior meckelian foramen. However, the jaw also possesses certain unique features which justify the erection of a new genus separate from Lapillopsis. For example, the mandible is twice the size of any jaws referred to other lapillopsids. The most notable unique feature is an enlarged "pump-handle" shaped arcadian process at the back of the jaw. This structure is responsible for the generic name of this genus, as "Manubrantlia" translates from Latin to the English expression "pump-handle". The type and only known species of this genus is Manubrantlia khaki. The specific name refers to the greenish-brown mudstones of the Panchet Formation, with a color that had been described as "khaki" by the first British geologists who studied the formation.

<span class="mw-page-title-main">Balfour Formation</span> Geological formation in the Beaufort Group of South Africa

The Balfour Formation is a geological formation that is found in the Beaufort Group, a major geological group that forms part of the greater Karoo Supergroup in South Africa. The Balfour Formation is the uppermost formation of the Adelaide Subgroup which contains all the Late Permian - Early Triassic aged biozones of the Beaufort Group. Outcrops and exposures of the Balfour Formation are found from east of 24 degrees in the highest mountainous escarpments between Beaufort West and Fraserburg, but most notably in the Winterberg and Sneeuberg mountain ranges near Cradock, the Baviaanskloof river valley, Graaff-Reniet and Nieu Bethesda in the Eastern Cape, and in the southern Free State province.

<span class="mw-page-title-main">Katberg Formation</span> Geological formation in the Beaufort Group of the Karoo Supergroup in South Africa

The Katberg Formation is a geological formation that is found in the Beaufort Group, a major geological group that forms part of the greater Karoo Supergroup in South Africa. The Katberg Formation is the lowermost geological formation of the Tarkastad Subgroup which contains the Lower to Middle Triassic-aged rocks of the Beaufort Group. Outcrops and exposures of the Katberg Formation are found east of 24 degrees onwards and north of Graaff-Reniet, Nieu Bethesda, Cradock, Fort Beaufort, Queensdown, and East London in the south, and ranges as far north as Harrismith in deposits that form a ring around the Drakensberg mountain ranges.

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

Thliptosaurus is an extinct genus of small kingoriid dicynodont from the latest Permian period of the Karoo Basin in KwaZulu-Natal, South Africa. It contains the type and only known species T. imperforatus. Thliptosaurus is from the upper Daptocephalus Assemblage Zone, making it one of the youngest Permian dicynodonts known, living just prior to the Permian mass extinction. It also represents one of the few small bodied dicynodonts to exist at this time, when most other dicynodonts had large body sizes and many small dicynodonts had gone extinct. The unexpected discovery of Thliptosaurus in a region of the Karoo outside of the historically sampled localities suggests that it may have been part of an endemic local fauna not found in these historic sites. Such under-sampled localities may contain 'hidden diversities' of Permian faunas that are unknown from traditional samples. Thliptosaurus is also unusual for dicynodonts as it lacks a pineal foramen, suggesting that it played a much less important role in thermoregulation than it did for other dicynodonts.

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

Counillonia is an extinct genus of dicynodont therapsid from the area of Luang Prabang in Laos, Southeast Asia that lived at around the time of the Permian-Triassic boundary and possibly dates to the earliest Early Triassic. Its type and only known species is C. superoculis. Counillonia was related to the Triassic dicynodonts such as Lystrosaurus and the Kannemeyeriiformes that survived the Permian mass extinction, but it was more closely related to the Permian genus Dicynodon than to either of these lineages. Counillonia may then possibly represent another line of dicynodonts that survived the Permian mass extinction into the Triassic period, depending on its age. The discovery of Counillonia in Laos and its unexpected evolutionary relationships hint at the less well understood geographies of dicynodont diversity across the Permo-Triassic boundary outside of well explored regions like the Karoo Basin in South Africa.

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

Repelinosaurus is an extinct genus of dicynodont from the Purple Claystone Formation of Luang Prabang in Laos, Southeast Asia that lived at around the time of the Permian-Triassic boundary and possibly dates to the earliest Early Triassic. Its type and only known species is R. robustus. Repelinosaurus was originally described as the earliest known kannemeyeriiform dicynodont, supporting the idea of a more rapid radiation of the Triassic kannemeyeriiform dicynodonts during the Early Triassic following the Permian mass extinction. However, it may alternatively be more closely related to the Permian Dicynodon. The discovery of a potential early kannemeyeriiform in an understudied locality like Laos highlights the importance of such places in dicynodont research, which has been largely focused on historically important localities such as the Karoo Basin of South Africa.

References

  1. ↑ Cluver, Michael Albert (1978). Fossil reptiles of the South African Karoo. The South African Museum. ISBN   9780908407583.
  2. ↑ Damiani, R.J.; Neveling, J.; Modesto, S.P. & Yates, A.M. (2004). "Barendskraal, a diverse amniote locality from the Lystrosaurus assemblage zone, Early Triassic of South Africa". Palaeontologia Africana. 39: 53–62.
  3. 1 2 Wallace, David Rains (2000). The Bonehunters' Revenge: Dinosaurs, Greed, and the Greatest Scientific Feud of the Gilded Age. Houghton Mifflin Harcourt. pp. 44–45. ISBN   978-0-618-08240-7.
  4. ↑ Liddell, Henry George & Scott, Robert, eds. (1980). A Greek-English Lexicon (abridged ed.). Oxford, UK: Oxford University Press. ISBN   978-0-19-910207-5.
  5. ↑ Lubick, Naomi (February 2005). "Investigating the Antarctic". Geotimes. American Geosciences Institute – via agiweb.org.
  6. ↑ Trewick, Steve (2016). "Plate Tectonics in Biogeography". International Encyclopedia of Geography: People, the Earth, Environment and Technology. John Wiley & Sons, Ltd. pp. 1–9. doi:10.1002/9781118786352.wbieg0638. ISBN   9781118786352.
  7. 1 2 3 4 5 6 Surkov, M.V.; Kalandadze, N.N. Of & Benton, M.J. (June 2005). "Lystrosaurus georgi, a dicynodont from the Lower Triassic of Russia" (PDF). Journal of Vertebrate Paleontology. 25 (2): 402–413. doi:10.1671/0272-4634(2005)025[0402:LGADFT]2.0.CO;2. ISSN   0272-4634. S2CID   59028100. Archived from the original (PDF) on 19 December 2008. Retrieved 7 July 2008.
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    Full version available at Botha; Smith (2007). Lystrosaurus species composition across the Permo–Triassic boundary in the Karoo Basin of South Africa (PDF) (Report). Archived from the original (PDF) on 10 September 2008. Retrieved 2 July 2008.
  9. ↑ Grine, F.E.; Forster, C.A.; Cluver, M.A. & Georgi, J.A. (2006). Amniote Paleobiology: Perspectives on the evolution of mammals, birds, and reptiles. University of Chicago Press. pp. 432–503.
  10. ↑ Bandyopadhyay, Saswati; Ray, Sanghamitra (1 March 2020). "Gondwana vertebrate faunas of India: Their diversity and intercontinental relationships". Episodes Journal of International Geoscience. 43 (1): 438–460. doi: 10.18814/epiiugs/2020/020028 .
  11. ↑ Angielczyk, Kenneth D.; Liu, Jun; Sidor, Christian A.; Yang, Wan (1 November 2022). "The stratigraphic and geographic occurrences of Permo-Triassic tetrapods in the Bogda Mountains, NW China — Implications of a new cyclostratigraphic framework and Bayesian age model". Journal of African Earth Sciences. 195: 104655. doi: 10.1016/j.jafrearsci.2022.104655 . ISSN   1464-343X.
  12. ↑ Han, Fenglu; Zhao, Qi; Liu, Jun (18 March 2021). "Preliminary bone histological analysis of Lystrosaurus (Therapsida: Dicynodontia) from the Lower Triassic of North China, and its implication for lifestyle and environments after the end-Permian extinction". PLoS One . 16 (3): e0248681. doi: 10.1371/journal.pone.0248681 . ISSN   1932-6203. PMC   7971864 . PMID   33735263.
  13. ↑ Cosgriff, J.W.; Hammer, W.R.; Ryan, W.J. (1982). "The Pangaean reptile, Lystrosaurus maccaigi, in the Lower Triassic of Antarctica". Journal of Paleontology. 56 (2): 371–385. ISSN   0022-3360. JSTOR   1304463.
  14. ↑ "Lystrosaurus". Encyclopaedia Britannica. Fossils & Facts. Retrieved 18 March 2019.
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  17. ↑ Smith, R.M.H.; Botha, J.; Vigilietti, P.A. (2022). "Taphonomy of drought afflicted tetrapods in the Early Triassic Karoo Basin, South Africa". Palaeogeography, Palaeoclimatology, Palaeoecology. 604. 111207. Bibcode:2022PPP...60411207S. doi:10.1016/j.palaeo.2022.111207. S2CID   251781291.
  18. ↑ "These fossil mummies reveal a brutal world long before T. rex lived". gizmodo.com. 20 September 2022.
  19. 1 2 3 Benton, M.J. (2006). When Life Nearly Died: The greatest mass extinction of all time. London, UK: Thames & Hudson. ISBN   978-0-500-28573-2.
  20. 1 2 Cokinos, Christopher (12 October 2007) [May-June 2007]. "The consolations of extinction". Orion . Archived from the original on 12 October 2007.
  21. ↑ "Clash of titans". Life before Dinosaurs (renamed 'Walking with Monsters'). Series 3. November 2005. BBC, Discovery Channel.
  22. ↑ Huttenlocker, A.K.; Sidor, C.A.; Smith, R.M.H. (2011). "A new specimen of Promoschorhynchus (Therapsida: Therocephalia: Akidnognathidae) from the Lower Triassic of South Africa and its implications for theriodont survivorship across the Permo-Triassic boundary". Journal of Vertebrate Paleontology. 31 (2): 405–421. Bibcode:2011JVPal..31..405H. doi:10.1080/02724634.2011.546720. S2CID   129242450.
  23. ↑ Sahney, S. & Benton, M.J. (2008). "Recovery from the most profound mass extinction of all time". Proceedings of the Royal Society B: Biological Sciences. 275 (1636): 759–65. doi:10.1098/rspb.2007.1370. PMC   2596898 . PMID   18198148.
  24. ↑ Erwin, D.H. (1993). The Great Paleozoic Crisis: Life and death in the Permian. Columbia University Press. ISBN   978-0-231-07467-4.
  25. ↑ "Fossil evidence of 'hibernation-like' state in 250 million-year-old Antarctic animal". phys.org. August 2020. Retrieved 7 September 2020.
  26. ↑ "Fossil suggests animals have been hibernating for 250 million years". UPI . Retrieved 7 September 2020.
  27. ↑ Whitney, Megan R.; Sidor, Christian A. (27 August 2020). "Evidence of torpor in the tusks of Lystrosaurus from the Early Triassic of Antarctica". Communications Biology. 3 (1): 471. doi:10.1038/s42003-020-01207-6. ISSN   2399-3642. PMC   7453012 . PMID   32855434. CC-BY icon.svg Text and images are available under a Creative Commons Attribution 4.0 International License.
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