Article

The dicynodont Lystrosaurus from the Upper Permian of Zambia: Evolutionary and stratigraphical implications

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Abstract

The skull of the dicynodont Lystrosaurus cf. curvatus is described from the Late Permian Madumabisa Mudstones of Zambia, in association with several Upper Permian genera. It demonstrates that the widespread Lystrosaurus, hitherto regarded as characteristic of the Lower Triassic, cannot be used in isolation as a biostratigraphical zone fossil. It appears that Lystrosaurus was a survivor of the Permo-Triassic extinction event, rather than a product of early Triassic diversification of other surviving forms. Its absence from the Upper Permian of South Africa suggests that it may have been an immigrant from further north. The Upper Permian fauna of the Madumabisa Mudstones is comparable to that of the Upper Guodikeng Formation of China. The fauna is younger than that of the Dicynodon Assemblage Zone of South Africa, but may be contemporaneous with that of the Cuttie's Hillock Formation of Scotland.

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... To date, collecting efforts have resulted in several hundred specimens that are distributed among the Iziko: South African Museum (Prentice's and Dixey's collections), the Bernard Price Institute for Palaeontological Research (specimens from the 1960 and 1961 expeditions), The Livingstone Museum (a small number of specimens from the 1963 expedition), and The Natural History Museum (most specimens from the 1963 expedition); material from the 1974 expedition is currently housed at Oxford University but it and specimens from the 2009 expedition will be returned to the National Heritage Conservation Commission of Zambia. Much of this material is all but unstudied, and only a handful of papers focusing on dicynodonts from the Luangwa Basin have been published (Boonstra 1938;Cox 1969;Crozier 1970;Keyser 1979;Keyser and Cruickshank 1979;King 1981;Gale 1988;King and Jenkins 1997;Angielczyk 2002), although some described particular specimens in great detail. Of the material that has been published, a considerable proportion has been included in taxonomic revisions, and in some cases multiple revisions (Keyser 1973c(Keyser , 1975Keyser and Cruickshank 1979;Angielczyk 2002;Renaut et al. 2003;Botha and Angielczyk 2007;Kammerer et al. 2011). ...
... For specimens collected in the northern part of the basin by Dixey and the 1960Dixey and the , 1961Dixey and the , and 1963 expeditions, we use the Drysdall and Kitching (1963;also see Kitching 1963) locality numbering system, which incorporates and standardizes all localities up to that time. For specimens collected by the 1974 expedition, we use the numbering system of Kerr (1974), which was used in most of the papers describing material from this collection (Kemp 1979(Kemp , 1980bDavies 1981;King 1981) and can be directly related to information provided in other publications that do not refer to localities by number (Kemp 1975;King and Jenkins 1997). Finally, we use our locality numbers for specimens collected during the 2009 expedition (i.e., NHCC specimens with locality numbers starting with ''L''). ...
... Gale (1989) referred the same specimens to Dicynodon clarencei (a synonym of Dicynodontoides recurvidens; see Angielczyk et al. 2009), but they also lack diagnostic characters for that species. Anderson and Cruickshank (1978), King (1988King ( , 1992, King and Jenkins (1997), Rubidge (2005), and Fröbisch (2009) included Diictodon in the faunal lists they compiled for Zambia. Angielczyk and Sullivan (2008) figured a largely unprepared but diagnostic Zambian Diictodon specimen (BP/1/3598). ...
... Lystrosaurus is a well-known dicynodont ( Fig. 1), remains of which have been recovered from Zambia, India, China, Mongolia, Russia, Antarctica, Australia and Laos (Kemp 1982;Gubin & Sinitza 1993;King 1993;King & Jenkins 1997;Retallack & Krull 1999), but it is particularly abundant in the Karoo Basin of South Africa (Rubidge 1995;Smith 1995). It is a medium-to large-sized genus with an average adult basal skull length ranging from 109 mm to 258 mm (depending on the species). ...
... As L. maccaigi is significantly larger (up to twice the size) than the other three species, it would have occupied a different feeding niche. It has previously been suggested that Lystrosaurus was pre-adapted to feeding on the Dicroidium-dominated flora of the Early Triassic (King & Jenkins 1997) and drought-resistant horsetails (Smith 1995), but it is possible that, as such a large animal, L. maccaigi was dependent on the taller, larger elements of the Glossopteris flora, which did not survive the end-Permian extinction. ...
... At present, its narrow range spans the P-T boundary and as such, can tentatively be regarded as an indicator fossil of the boundary interval. L. curvatus is considered to be the least derived of the Lystrosaurus species, as it appears to be morphologically closest to the rest of the Permian dicynodonts (Brink 1951;Cluver 1971;King & Jenkins 1997). Thus, L. curvatus may have been able to survive the end-Permian extinction as one of the more generalized species, which are thought to be less susceptible to environmental change compared to more derived species (Stanley 1990). ...
Article
Lystrosaurus is one of the few therapsid genera that survived the end-Permian mass extinction, and the only genus to have done so in abundance. This study identifies which species of Lystrosaurus have been recovered from Permian and Triassic strata to determine changes in the species composition across the Permo–Triassic (P–T) boundary in the Karoo Basin of South Africa. Data generated from museum collections and recent fieldwork were used to stratigraphically arrange a total of 189 Lystrosaurus specimens to determine which species survived the extinction event. Results reveal that L. curvatus and L. maccaigi lived together on the Karoo floodplains immediately before the extinction event. L. maccaigi did not survive into the Triassic in South Africa. L. curvatus survived, but did not flourish and soon became extinct. Two new species of Lystrosaurus , L. murrayi and L. declivis , appeared in the Early Triassic. It is possible that L. murrayi and L. declivis occupied different niches to L. maccaigi and L. curvatus , and had special adaptations that were advantageous in an Early Triassic environment. We suggest that L. maccaigi may be used as a biostratigraphic marker to indicate latest Permian strata in South Africa and that, in support of previous proposals, the genus Lystrosaurus should not be used as a sole indicator of Triassic-aged strata. Our field data also show that L. curvatus may be regarded as a biostratigraphic indicator of the P–T boundary interval. End-Permian extinction, Karoo Basin, Lystrosaurus , Permo– Triassic.
... To date, collecting efforts have resulted in several hundred specimens that are distributed among the Iziko: South African Museum (Prentice's and Dixey's collections), the Bernard Price Institute for Palaeontological Research (specimens from the 1960 and 1961 expeditions), The Livingstone Museum (a small number of specimens from the 1963 expedition), and The Natural History Museum (most specimens from the 1963 expedition); material from the 1974 expedition is currently housed at Oxford University but it and specimens from the 2009 expedition will be returned to the National Heritage Conservation Commission of Zambia. Much of this material is all but unstudied, and only a handful of papers focusing on dicynodonts from the Luangwa Basin have been published (Boonstra 1938;Cox 1969;Crozier 1970;Keyser 1979;Keyser and Cruickshank 1979;King 1981;Gale 1988;King and Jenkins 1997;Angielczyk 2002), although some described particular specimens in great detail. Of the material that has been published, a considerable proportion has been included in taxonomic revisions, and in some cases multiple revisions (Keyser 1973c(Keyser , 1975Keyser and Cruickshank 1979;Angielczyk 2002;Renaut et al. 2003;Botha and Angielczyk 2007;Kammerer et al. 2011). ...
... For specimens collected in the northern part of the basin by Dixey and the 1960Dixey and the , 1961Dixey and the , and 1963 expeditions, we use the Drysdall and Kitching (1963;also see Kitching 1963) locality numbering system, which incorporates and standardizes all localities up to that time. For specimens collected by the 1974 expedition, we use the numbering system of Kerr (1974), which was used in most of the papers describing material from this collection (Kemp 1979(Kemp , 1980bDavies 1981;King 1981) and can be directly related to information provided in other publications that do not refer to localities by number (Kemp 1975;King and Jenkins 1997). Finally, we use our locality numbers for specimens collected during the 2009 expedition (i.e., NHCC specimens with locality numbers starting with ''L''). ...
... Gale (1989) referred the same specimens to Dicynodon clarencei (a synonym of Dicynodontoides recurvidens; see Angielczyk et al. 2009), but they also lack diagnostic characters for that species. Anderson and Cruickshank (1978), King (1988King ( , 1992, King and Jenkins (1997), Rubidge (2005), and Fröbisch (2009) included Diictodon in the faunal lists they compiled for Zambia. Angielczyk and Sullivan (2008) figured a largely unprepared but diagnostic Zambian Diictodon specimen (BP/1/3598). ...
Chapter
Full-text available
Dicynodont fossils were first collected in the Luangwa Basin, Zambia, in the 1920s, but limited detailed study and taxonomic uncertainty have obscured their biostratigraphic utility and their implications for topics such as dicynodont biogeography and the effects of the end-Permian extinction. Here we present a comprehensive taxonomic revision of the dicynodonts of the Luangwa Basin, taking into account specimens in all major museum collections and new material collected by our team in 2009. We recognize 14 dicynodont species from the Upper Permian Upper Madumabisa Mudstone: Pristerodon mackayi, Endothiodon sp., Diictodon feliceps, Compsodon helmoedi, Emydops sp., Dicynodontoides cf. D. nowacki, a new tusked cistecephalid, cf. Katumbia parringtoni, Kitchinganomodon crassus, Oudenodon bainii, Odontocyclops whaitsi, Dicynodon huenei, Syops vanhoepeni, and a new lystrosaurid. Previous reports of Lystrosaurus in the basin appear to be in error. In addition, we found no significant partitioning of dicynodont taxa in the northern and southern parts of the basin, despite substantial differences in preservation, indicating the presence of a single faunal assemblage in the Upper Permian. The Madumabisa dicynodont assemblage is best correlated with the Cistecephalus Assemblage Zone of South Africa. The shared presence of Dicynodon huenei and possibly Katumbia in the Luangwa Basin and the Ruhuhu Basin of Tanzania suggests that the Tanzanian Usili Formation also can be correlated with the Cistecephalus zone. Interestingly, the Madumabisa assemblage from Zambia is more similar to the coeval assemblage from South Africa, despite its closer geographic proximity to Tanzania. The Karoo and Ruhuhu basins also include more endemic species in the Permian than the Luangwa Basin. The Middle Triassic Ntawere Formation preserves four dicynodont species (Kannemeyeria lophorhinus, “Kannemeyeria” latirostris, Zambiasaurus submersus, Sangusaurus edentatus), which occur at two stratigraphic levels. The lower Ntawere assemblage resembles that of the Omingonde Formation of Namibia in the presence of Kannemeyeria lophorhinus and potentially Dolichuranus (if “K.” latirostris represents this taxon). The upper Ntawere assemblage shares the genus Sangusaurus with that of the Manda beds of Tanzania and includes the endemic Zambiasaurus. Comparisons of these assemblages to the Omingonde and Manda suggest that both are best correlated with the Cynognathus C subzone. When combined with data on other tetrapod taxa, our revised dicynodont assemblages contribute to an emerging picture of broad faunal similarity in southern and eastern Africa during the Late Permian, and increasing differentiation between the South African and other Karoo basins following the end-Permian extinction.
... As L. maccaigi is significantly larger (up to twice the size) than the other three species, it would have occupied a different feeding niche. It has previously been suggested that Lystrosaurus was pre-adapted to feeding on the Dicroidium-dominated flora of the Early Triassic (King & Jenkins 1997) and drought-resistant horsetails (Smith 1995), but it is possible that, as such a large animal, L. maccaigi was dependent on the taller, larger elements of the Glossopteris flora, which did not survive the end-Permian extinction. Remains of L. curvatus have been recovered from the latest Permian and earliest Triassic Palingkloof Member of the Balfour Formation and have yet to be found in the Katberg Formation. ...
... At present, its narrow range spans the P–T boundary and as such, can tentatively be regarded as an indicator fossil of the boundary interval. L. curvatus is considered to be the least derived of the Lystrosaurus species, as it appears to be morphologically closest to the rest of the Permian dicynodonts (Brink 1951; Cluver 1971; King & Jenkins 1997). Thus, L. curvatus may have been able to survive the end-Permian extinction as one of the more generalized species, which are thought to be less susceptible to environmental change compared to more derived species (Stanley 1990). ...
... – Several authors have noted that the appearance of Lystrosaurus in the fossil record is relatively sudden, and they have suggested that the genus may have migrated into the South African Karoo Basin (e.g. Kitching 1977; Smith 1995; King & Jenkins 1997). On the basis of a skull, identified as L. curvatus, from the Madumabisa Mudstones of Zambia, King & Jenkins (1997) suggested that L. curvatus was an immigrant to the South African Karoo basin. ...
Article
Lystrosaurus is one of the few therapsid genera that survived the end-Permian mass extinction, and the only genus to have done so in abundance. This study identifies which species of Lystrosaurus have been recovered from Permian and Triassic strata to determine changes in the species composition across the Permo–Triassic (P–T) boundary in the Karoo Basin of South Africa. Data generated from museum collections and recent fieldwork were used to stratigraphically arrange a total of 189 Lystrosaurus specimens to determine which species survived the extinction event. Results reveal that L. curvatus and L. maccaigi lived together on the Karoo floodplains immediately before the extinction event. L. maccaigi did not survive into the Triassic in South Africa. L. curvatus survived, but did not flourish and soon became extinct. Two new species of Lystrosaurus, L. murrayi and L. declivis, appeared in the Early Triassic. It is possible that L. murrayi and L. declivis occupied different niches to L. maccaigi and L. curvatus, and had special adaptations that were advantageous in an Early Triassic environment. We suggest that L. maccaigi may be used as a biostratigraphic marker to indicate latest Permian strata in South Africa and that, in support of previous proposals, the genus Lystrosaurus should not be used as a sole indicator of Triassic-aged strata. Our field data also show that L. curvatus may be regarded as a biostratigraphic indicator of the P–T boundary interval.
... The distribution of the genus Lystrosaurus of the latest Permian to late Olenekian time (Fig. 15D2) is most instructive. This sheep-size dicynodont originated in east Africa in the latest Permian (Cosgriff, 1965;King and Jenkins, 1997;Lucas, 2006) and rapidly colonized the eastern half of the earliest Triassic Pangea, using the Cathaysian bridge to cross over to Laurasia going as far west as the Moscow basin, but not farther into the arid world of western Pangea. It has commonly been viewed as a cosmopolitan animal with universal distribution in Pangea. ...
... They were adapted to live in the low-oxygen world of the end-Permian and for that reason seem to have preferred the relatively lower and less harsh eastern Pangea as opposed to the desert-and mountain-dominated western Pangea as their abode. The Lystrosaurus, for example, originated very near the Gulf of Malagasy of Gondwana-Land, in east Africa (King and Jenkins, 1997), and marched east (and southwest) and most likely headed north across the Cathaysian bridge, in the footsteps of its Dicynodon cousins (Battail, 1997), to reach the extensional lacustrine basins of the post-Altaid world in central Asia, 43 from where it made it to the lowlands of the Moscow basin in the essentially depopulated world of the early Triassic. ...
... 5). If viable, these magnetostratigraphic data indicate the lowest occurrence of Lystrosaurus in a reverse polarity magnetozone older than the PTB (as already suggested by King andJenkins, 1997, andSmith, 2007, among others). If true, the highest occurrence of Daptocephalus (Dicynodon) based on Smith and Both-Brink's data is closer to the PTB (Fig. 5). ...
... According to the magnetostratigraphic records in the marine realm, the duration over which the end-Permian extinction occurred is positioned in an interval of relatively long normal magnetic polarity. An interval of normal polarity is reportedly associated with the Daptocephalus -Lystrosaurus AZ turnover above an underlying interval of reverse polarity (Ward et al., 2005;Steiner, 2006), in which the first appearance of Lystrosaurus is recognised (King and Jenkins, 1997;Botha and Smith, 2007). Lucas (2009) interpreted this pattern as evidence that this biozone contact predated the marine extinction. ...
Research
The guidebook for a pre-meeting field trip to many of the classic reported, vertebrate-defined Permian--Triassic boundary sections in the Karoo Basin, South Africa. An extensive background of concepts and literature surrounding the currently , and widely, accepted model for ecosystem change in the continental record of the late Permian is provided in the Introductory materials. This discussion is followed by field trip stops, with previously published and new data by the authors, at Bethulie (Day 2: Free State), Carlton Heights and Lootsberg Pass (Day 3: Eastern Cape Province), Old Lootsberg Pass (Day 4: Eastern Cape Province), and Wapadsberg Pass and Commandodrift Dam (Day 5: Eastern Cape Province).
... The distribution of the genus Lystrosaurus of the latest Permian to late Olenekian time (Fig. 15D2) is most instructive. This sheep-size dicynodont originated in east Africa in the latest Permian (Cosgriff, 1965;King and Jenkins, 1997;Lucas, 2006) and rapidly colonized the eastern half of the earliest Triassic Pangea, using the Cathaysian bridge to cross over to Laurasia going as far west as the Moscow basin, but not farther into the arid world of western Pangea. It has commonly been viewed as a cosmopolitan animal with universal distribution in Pangea. ...
... They were adapted to live in the low-oxygen world of the end-Permian and for that reason seem to have preferred the relatively lower and less harsh eastern Pangea as opposed to the desert-and mountain-dominated western Pangea as their abode. The Lystrosaurus, for example, originated very near the Gulf of Malagasy of Gondwana-Land, in east Africa (King and Jenkins, 1997), and marched east (and southwest) and most likely headed north across the Cathaysian bridge, in the footsteps of its Dicynodon cousins (Battail, 1997), to reach the extensional lacustrine basins of the post-Altaid world in central Asia, 43 from where it made it to the lowlands of the Moscow basin in the essentially depopulated world of the early Triassic. ...
Chapter
The Tethyan realm stretches across the Old World from the Atlantic to the Pacific Oceans along the Alpine-Himalayan mountain ranges and extends into their fore- and hinterlands as far as the old continental margins of the now-vanished Tethyan oceans reached. It contains the Tethyside superorogenic complex, including the orogenic complexes of the Cimmerides and the Alpides, the products of the closure of the Paleo- and the Neo-Tethyan oceans, respectively. Paleo-Tethys was the oceanic realm that originated when the late Paleozoic Pangea was assembled by the final Uralide-Scythide-Hercynide-Great-Appalachide collisions. It was a composite ocean, i.e., not one formed by the rifting of its opposing margins, and its floor was already being consumed along both Laurasia-and Gondwana-Land-flanking subduction zones when it first ppeared. The Gondwana-Land-flanking subduction systems, in particular, created mostly extensional arc families that successively led to various Paleo-Tethyan marginal basins, the last group of which was the oceans that united to form the Neo-Tethys. The Paleo-Tethys may have become an entirely continent-locked ocean through the construction, to the east of it, of a Cathaysian bridge uniting various elements of China and Indochina into an isthmian link between Laurasia and Gondwana-Land during the latest Permian, inhibiting any deep-sea connection between the Paleo-Tethys and the Panthalassa. That land bridge may have been responsible for the peculiarities in the distribution of the latest Permian-early Triassic Dicynodonts and possibly some brachiopods, benthic marine microorganisms, and land plants. The existence of the Cathaysian bridge seems to have helped the formation of anoxic conditions in the Paleo-Tethys. In fact, it seems that the major Permian extinctions began in the Paleo-Tethys and were really mainly felt in it and in areas infl uenced by it. This isolated setting of the Paleo-Tethys we refer to as a Ptolemaic condition, in reference to the isolated oceans Claudius Ptolemy had depicted on a geocratic Earth in his world map in the second century AD. Ptolemaic conditions are not uncommoni n the history of Earth. Today, such a condition is represented by the Mediterranean and its smaller dependencies such as the Black Sea and the South Caspian Ocean. Para-Tethys in the Neogene had a similar but even more isolated setting. As we see in all these late Cenozoic cases, such Ptolemaic oceans have a major infl uence on the evolution of the biosphere. The Paleo-Tethys seems to have had a much larger impact than any of its successors owing to its immense size and may have been the key player in the so-called "end-Permian" extinction, which, in reality, was a mid to late Permian affair, with some late phases even in the earliest Triassic. The Permian extinction happened in at least two main phases, one in the Guadalupian and the other near the end of the Lopingian, and in each phase different animal and plant groups became extinct diachronously, phasing out according to the degree they were infl uenced by the developing anoxia within the Paleo-Tethys. What these conclusions suggest is that when investigating the causes of past events, regional geology must always form the foundation of all other considerations. Many speculations concerning the Permian extinction events cannot be adequately assessed without placing their implications into the geography of the times to which they are relevant. A purely "process-orientated" research that downplays or ignores regional geology and attempts to ape physics and chemistry, as is now prevalent in the United States and in western Europe and regrettably encouraged by the funding organizations, is doomed to failure. Copyright
... This genus was traditionally considered to have first appeared in the Early Triassic. The discovery of an overlap in the stratigraphic ranges of Dicynodon and Lystrosaurus has demonstrated that the latter also occurs the Late Permian and thus it was the only dicynodont known to have survived the end Permian mass extinction (Cheng, 1993;Smith, 1995;King and Jenkins, 1997;Smith and Ward, 2001). ...
... Taxa (resolution at both generic and family level) which correlate with those from South Africa are: Gondwana Madagascar; Lower Sakamena Formation: rhinesuchid amphibian Uranocentrodon (Schoch and Milner, 2000), dicynodont Oudenodon (Mazin and King, 1991 (Gay and Cruickshank, 1999;von Huene 1950 (Kemp, 1975), cynodont Procynosuchus (Kemp, 1979), dicynodonts Dicynodon (King, 1981), Diictodon (Gale, 1988), Oudenodon (King, 1979), Lystrosaurus (King and Jenkins, 1997). ...
... As the dominant element of Upper Permian terrestrial ecosystems, it has often been stated that dicynodonts suffered from a substantial decrease in taxonomic diversity (King, 1990bKing, , 1991 Maxwell, 1992;), before they successfully diversified again in the Triassic period. It is important to note that there is only a single dicynodont species, Lystrosaurus curvatus, which is known from below as well as above the Permian–Triassic boundary (King & Jenkins, 1997;). As a result, it has often been stated that Lystrosaurus was the only dicynodont that survived the end-Permian extinction (Benton, 2003; Retallack, Smith & Ward, 2003 ). ...
... As the dominant element of Upper Permian terrestrial ecosystems, it has often been stated that dicynodonts suffered from a substantial decrease in taxonomic diversity ( King, 1990bKing, , 1991Maxwell, 1992;), before they successfully diversified again in the Triassic period. It is important to note that there is only a single dicynodont species, Lystrosaurus curvatus, which is known from below as well as above the Permian-Triassic boundary ( King & Jenkins, 1997;). As a result, it has often been stated that Lystrosaurus was the only dicynodont that survived the end-Permian extinction ( Benton, 2003;Retallack, Smith & Ward, 2003). ...
Article
Full-text available
Redescription of the small Triassic dicynodont Kombuisia frerensis Hotton reveals new information about its cranial anatomy. On the basis of the new data, the previously suggested hypothesis of a close relationship of Kombuisia and the Permian genus Kingoria is tested within a phylogenetic framework. For this a total evidence analysis of Permian anomodont relationships was performed by combining existing data matrices into a comprehensive data set that includes basal anomodonts, dicynodonts and a large number of morphological characters. The resulting phylogenetic hypothesis corroborates the sister-taxon relationship of Kombuisia and Kingoria. This is based on a number of synapomorphies, including the narrow intertemporal region that forms a sagittal crest, a reduced mandibular fenestra, the presence of a dorsolateral notch in occipital view of the squamosal, a relatively wide mid-ventral plate of the vomer and a dorsal stapedial process. The general topology of this phylogeny supports the main aspects of recent hypotheses of anomodont relationships, and not only resolves critical nodes at the base of the Dicynodontia that were previously obscured by polytomies, but also introduces new hypotheses of relationships. Furthermore, the phylogenetic position of Kombuisia has implications for the survivorship of the Dicynodontia across the Permian–Triassic boundary. With consideration of ghost lineages there are at least four dicynodont lineages that extend beyond the end-Permian extinction event. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society, 2007, 150, 117–144.
... Species of this genus have been described from Asia (China and India), Europe (Russia), Africa (South Africa and Zambia), and Antarctica (e.g. Young, 1946;Cluver, 1971;Colbert, 1974;King, 1991;King and Jenkins, 1997;Ray, 2005;Surkov et al., 2005). Lystrosaurus fossils are the most commonly encountered vertebrate remains in lowermost Triassic rocks of the Karoo Basin, South Africa; Groenewald and Kitching (1995) estimated that 95% of the fossils from the Lystrosaurus declivis Assemblage Zone of the Karoo Basin are attributable to Lystrosaurus. ...
Article
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The term “disaster species” was a term originally conceived to describe marine microfossils that exhibited profound abundances in the wake of a biological crisis. The term was expanded in the 1990s to describe (as “disaster taxa”) opportunistic taxa that dominated their biota numerically (“bloomed”) during the survival interval of a mass extinction event. The Permo-Triassic tetrapod genus Lystrosaurus has been cited regularly as a “disaster taxon” of the end-Permian mass extinction. A review of the definitions that have been developed for disaster taxa, and data from recent biostratigraphic and phylogenetic studies that include species of Lystrosaurus, leads to the conclusion that the genus is not a “disaster taxon”. Further, the known biostratigraphy and tree topologies of species of Lystrosaurus do not satisfy more recent definitions that attribute diversification to disaster species. At most, species of Lystrosaurus that form the informal “Lystrosaurus abundant zone” in the lower Katberg Formation, Lower Triassic of South Africa, could be described as opportunistic species.
... The Karoo Basin is one of a system of related depositional basins extending through southern and eastern Africa that preserve varying amounts of Paleozoic and Mesozoic strata (Catuneanu et al., 2005). Many of these basins preserve some fossils (e.g., Lepper et al., 2000;Jacobs et al., 2005;Abdala et al., 2013;Castanhinha et al., 2013;Sidor et al., 2014;Kruger et al., 2015), but the Luangwa Basin of Zambia and the Ruhuhu Basin of Tanzania have extensive records of Permo-Triassic vertebrates that have been studied for nearly a century (e.g., Haughton, 1932;Stockley, 1932;Nowack, 1937;Boonstra, 1938;von Huene, 1938von Huene, , 1939von Huene, , 1942von Huene, , 1950Charig, 1956;Cox, 1959Cox, , 1969Cox, , 1972Cox, , 1991Panchen, 1959;Brink, 1963;Drysdall and Kitching, 1963;Cruickshank, 1965;Crozier, 1970;Howie, 1970;Crompton, 1972;Chernin, 1974;Kemp, 1975;Cox and Li, 1983;King and Jenkins, 1997;Lee et al., 1997;Gay and Cruickshank, 1999;Damiani, 2001;Angielczyk, 2002Angielczyk, , 2007Maisch, 2002Maisch, , 2005Maisch and Gebauer, 2005;Butler et al., 2009;Nesbitt et al., 2010Nesbitt et al., , 2013aNesbitt et al., , 2013bNesbitt et al., , 2014Nesbitt et al., , 2017Sidor et al., 2010;Simon et al., 2010;Nesbitt and Butler, 2013;Peecook et al., 2013;Tsuji et al., 2013;Angielczyk et al., 2014aAngielczyk et al., , 2014bEzcurra et al., 2014;Gebauer, 2014;Hopson, 2014;Cox and Angielczyk, 2015). Because the Luangwa and Ruhuhu basins do not preserve an Early Triassic fossil assemblage comparable to the Lystrosaurus Assemblage Zone of the Karoo Basin (Groenewald and Kitching, 1995; also see Smith and Botha-Brink, 2014;Viglietti et al., 2016), they have received little attention in the context of the Permo-Triassic extinction. ...
Article
The Permian-Triassic mass extinction (PTME) was one of the transformative events of the Phanerozoic, marked by extinction, post-Permian transformation of surviving ecosystems, and the formation of new communities. The South African Karoo Basin has served as the primary source of data on the terrestrial component of these events, but its global applicability remains poorly known. Here, we compare Permian-Triassic communities of the Karoo Basin with those from the Luangwa and Ruhuhu basins of Zambia and Tanzania, respectively, analyzing their functional structures and simulating dynamic responses to environmental perturbation. Results show that compositional similarities of late Permian communities among the basins underlie similarities in their dynamics and resistance to secondary extinction. The Karoo Basin ecosystem also displays evidence of a transformation to increased resistance during the late Permian. Although the Karoo Basin ecosystem was reduced significantly by the PTME, structural features of that resistance persisted into the Early Triassic, facilitated by a greater susceptibility to extinction of small-body-sized amniotes and large carnivorous amniotes. It was undone by the initial stages of postextinction restructuring. Continued evolution of the Triassic ecosystem led to a recovery of resistance, but in a community compositionally dissimilar from its Permian antecedents. Likewise, the upper part of the Lifua Member of the Manda Beds (Middle Triassic) of Tanzania was structurally distinct from the Karoo Basin communities but displayed similar dynamics. The recurrence and convergence of communities with different histories toward similar dynamics suggest that there are taxon-independent norms of community assembly and function operating on geological timescales. SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Roopnarine, P. D., K. D. Angielczyk, S. Olroyd, S. J. Nesbitt, J. Botha-Brink, B. R. Peecook, M. O. Day, and R. M. H. Smith. 2018. Comparative ecological dynamics of Permian-Triassic communities from the Karoo, Luangwa, and Ruhuhu basins of southern Africa; pp. 254–272 in C. A. Sidor and S. J. Nesbitt (eds.), Vertebrate and Climatic Evolution in the Triassic Rift Basins of Tanzania and Zambia. Society of Vertebrate Paleontology Memoir 17. Journal of Vertebrate Paleontology 37(6, Supplement).
... The Karoo Basin is one of a system of related depositional basins extending through southern and eastern Africa that preserve varying amounts of Paleozoic and Mesozoic strata (Catuneanu et al., 2005). Many of these basins preserve some fossils (e.g., Lepper et al., 2000;Jacobs et al., 2005;Abdala et al., 2013;Castanhinha et al., 2013;Sidor et al., 2014;Kruger et al., 2015), but the Luangwa Basin of Zambia and the Ruhuhu Basin of Tanzania have extensive records of Permo-Triassic vertebrates that have been studied for nearly a century (e.g., Haughton, 1932;Stockley, 1932;Nowack, 1937;Boonstra, 1938;von Huene, 1938von Huene, , 1939von Huene, , 1942von Huene, , 1950Charig, 1956;Cox, 1959Cox, , 1969Cox, , 1972Cox, , 1991Panchen, 1959;Brink, 1963;Drysdall and Kitching, 1963;Cruickshank, 1965;Crozier, 1970;Howie, 1970;Crompton, 1972;Chernin, 1974;Kemp, 1975;Cox and Li, 1983;King and Jenkins, 1997;Lee et al., 1997;Gay and Cruickshank, 1999;Damiani, 2001;Angielczyk, 2002Angielczyk, , 2007Maisch, 2002Maisch, , 2005Maisch and Gebauer, 2005;Butler et al., 2009;Nesbitt et al., 2010Nesbitt et al., , 2013aNesbitt et al., , 2013bNesbitt et al., , 2014Nesbitt et al., , 2017Sidor et al., 2010;Simon et al., 2010;Nesbitt and Butler, 2013;Peecook et al., 2013;Tsuji et al., 2013;Angielczyk et al., 2014aAngielczyk et al., , 2014bEzcurra et al., 2014;Gebauer, 2014;Hopson, 2014;Cox and Angielczyk, 2015). Because the Luangwa and Ruhuhu basins do not preserve an Early Triassic fossil assemblage comparable to the Lystrosaurus Assemblage Zone of the Karoo Basin (Groenewald and Kitching, 1995; also see Smith and Botha-Brink, 2014;Viglietti et al., 2016), they have received little attention in the context of the Permo-Triassic extinction. ...
... Platbergian records of Dicynodon in the Karoo basins are in part of the Kawinga Formation in the Ruhuhu basin (Gay & Cruickshank 1999;Maisch & Gebauer 2005) and 'Horizon 5' in the Madumabisa Mudstone Formation in Zambia (King & Jenkins 1997;Smith et al. 2012). In the Majunga basin of Madagascar, the lower Sakamena Formation yields Oudenodon, Rhinesuchus and various endemic reptiles (Mazin & King 1991;Smith 2000) and is probably of Steilkransian age. ...
Article
The most extensive Permian tetrapod (amphibian and reptile) fossil records from the western USA (New Mexico to Texas) and South Africa have been used to define 11 land vertebrate faunachrons (LVFs). These are, in ascending order, the Coyotean, Seymouran, Mitchellcreekian, Redtankian, Littlecrotonian, Kapteinskraalian, Gamkan, Hoedemakeran, Steilkransian, Platbergian and Lootsbergian. These faunachrons provide a biochronological framework with which to assign ages to, and correlate, Permian tetrapod fossil assemblages. Intercalated marine strata, radioisotopic ages and magnetostratigraphy were used to correlate the Permian LVFs to the standard global chronostratigraphic scale with varying degrees of precision. Such correlations identified the following significant events in Permian tetrapod evolution: a Coyotean chronofaunal event (end Coyotean); Redtankian events (Mitchellcreekian–Littlecrotonian); Olson's gap (late Littlecrotonian); a therapsid event (Kapteinskraalian); a dinocephalian extinction event (end Gamkan); and a latest Permian extinction event (Platbergian–Lootsbergian boundary). Problems of incompleteness, endemism and taxonomy, and the relative lack of non-biochronological age control continue to hinder the refinement and correlation of a Permian timescale based on tetrapod biochronology. Nevertheless, the global Permian timescale based on tetrapod biochronology is a robust tool for both global and regional age assignment and correlation. Advances in Permian tetrapod biochronology will come from new fossil discoveries, more detailed biostratigraphy and additional alpha taxonomic studies based on sound evolutionary taxonomic principles.
... Several authors have previously proposed migration as a reason for the appearance of the post-extinction Early Triassic Karoo fauna (Kitching, 1977;King and Jenkins, 1997;Reisz et al., 2000). Pfefferkorn (1999) noted that there are often no new species in a given region after an extinction that would be capable of filling recently vacated niches, and thus, new species would have to evolve and then migrate into the area. ...
Article
The mass extinction that occurred at the end of the Permian Period approximately 251 Mya is widely accepted as the most devastating extinction event in Earth’s history. An estimated 75–90% of global diversity from both marine and terrestrial realms disappeared synchronously within at most one million and perhaps as little as 100,000 years. To date, most research has focused on the marine record and it is only recently that a few fully preserved terrestrial Permo-Triassic boundary sequences have been discovered. The main Karoo Basin of South Africa hosts several well-preserved non-marine Permo-Triassic boundary sequences that have been the focus of intensive research into the nature of the extinction and its possible causes. This study uses sedimentological and biostratigraphic data from boundary sequences near Bethulie in the southern Karoo Basin to make assumptions about the rates and timing of recovery of the terrestrial fauna in this portion of southern Gondwana after the extinction event. The biostratigraphic data gathered from 277 in situ vertebrate fossils allows us to define more accurately the temporal ranges of several taxa. These data also confirm a more precise extinction rate in this part of the basin of 54% of latest Permian vertebrate taxa, followed by the onset of a relatively rapid recovery, within an estimated 40–50 thousand years (based on the calculation of floodplain aggradation rates and compaction ratios) that included the origination of at least 12 new vertebrate taxa from amongst the survivors.
... For anomodonts, this approach showed on a short temporal scale that at least four distinct generic lineages survived the end-Permian extinction [12], providing a more complete picture of anomodont survival across the PTB than before. Moreover, within the iconic genus Lystrosaurus there are three distinct species, L. curvatus, L. maccaigi, and L. hedini, that are known from below as well as above the Permian-Triassic boundary [13][14][15]. To obtain a complete picture of anomodont survivorship across the PTB it is necessary to also consider their phylogenetic relationships. ...
... Tetrapod assemblages of Platbergian age are: 1) Karoo basin, South Africa, where specimens of Dicynodon (= Daptocephalus) first occur in the upper Cistecephalus Assemblage Zone and are the dominant tetrapod fossils in the Dicynodon Assemblage Zone of the Teekloof and Balfour formations (Kitching, 1995); 2) The "lower bone bed" at Kingori in the Ruhuhu Basin of Tanzania (Haughton, 1932;Gay and Cruickshank, 1999); 3) "Horizon 5" of Boonstra in the Luangwa Valley, 4.8-6.4 km north of Nt'awere, Zambia (King and Jenkins, 1997); 4) Cutties Hillock Quarry, Elgin, Scotland (Newton, 1893;King, 1988) in the Cutties Hillock Sandstone Formation (Benton and Walker, 1985); 5) various localities of the upper Sokolki assemblage and Vyatskyan assemblage of the Russian upper Tatarian (Amalitzky, 1922;Sushkin, 1926;Ivakhnenko et al., 1997;Kurkin, 1999;Kalandadze and Kurkin, 2000;Golubev, 2000;Lucas, 2005b); 6) Quanzijie, Wutonggou and Guodikeng formations in the Junggur and Turpan basins, Xinjiang Province, China (Lucas, 1998a(Lucas, , 2001(Lucas, , 2005a; and (7) Sunan Formation, Gansu and Naobaogou Formation, Nei Monggol, both Ordos basin, China (Lucas 1998a(Lucas , 2001(Lucas , 2005aLi et al., 2000); and 8) north of the Mekong River in the Luang-Prabang area of Laos (Battail et al., 1995). ...
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... Kemp 1979 Kemp , 1980 King 1981). Notably, King & Jenkins (1997) identified a partial dicynodont skull as pertaining to Lystrosaurus, suggesting that it was a Permian representative of the predominantly Triassic taxon and that the upper Madumabisa Mudstone likely contained rocks of latest Permian age. This specimen was subsequently re-identified as a lystrosaurid, but not pertaining to Lystrosaurus itself (Angielczyk et al. 2014) A new fieldwork effort was initiated in 2009 with collaborators from the University of Washington, Field Museum of Natural History, Museum National d'Histoire Naturelle , Iziko South African Museum and the National Heritage Conservation Commission (Peecook et al. 2013; Sidor et al. 2013 Sidor et al. , 2014 Angielczyk et al. 2014). ...
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This contribution reports the first occurrence of a biarmosuchian therapsid from the upper Madumabisa Mudstone Formation of the Luangwa Basin of northeastern Zambia. Although incomplete, the fossil preserves diagnostic features of post-Biarmosuchus biarmosuchians, such as the presence of a preparietal bone and parasagittal ridges on the basicranial rami of the pterygoids, that allow its unambiguous referral to this group. Based primarily on the record of dicynodonts, the upper Madumabisa Mudstone assemblage can be correlated with the Cistecephalus Assemblage Zone of South Africa. During this interval, the tetrapod faunas of the Karoo and Luangwa basins were remarkably similar and likely characterized by frequent biotic interchange.
... The therapsids reported for Sanga do Cabral Formation include isolated stapes attributed to dicynodonts and tentatively assigned to Lystrosaurus by Schwanke and Kellner (1999) and Langer and Lavina (2000). It is currently known that the genus Lystrosaurus is not exclusively restricted to the Triassic, being found in the Upper Permian of Zambia and in the Permian-Triassic South African Karoo succession (King and Jenkins, 1997;Ward et al., 2005). Moreover, some fragmentary postcranial remains were assigned to putative non-mammalian cynodonts (Abdala et al., 2002), but such assignation is not well supported with the available specimens, as discussed previously. ...
Article
The Sanga do Cabral Formation of southern Brazil has a rich fossil tetrapod assemblage and is suggested to have an Early Triassic age mainly based on the presence of the parareptile Procolophon trigoniceps. However, a Permo-Triassic age can be also suggested for this unit taking into account the presence of putative Permian taxa and some previous stratigraphic assessments. We describe here several large vertebrae from the Sanga do Cabral Formation that display a distinctive morphology that includes the presence of a transverse distance across postzygapophyses more than twice the transverse width of the centrum, and accessory articulation structures in the neural arch that remind the hyposphene and hypantrum present in some basal parareptiles and diadectomorphs. Vertebrae with a similar large size and morphology had been previously reported from the same locality as belonging to the genus Procolophon based on their parareptile appearance (mainly the presence of a swollen neural arch) and the fact that the vertebrae were collected at the same locality where a large fragmentary skull assigned to this taxon was found. However, these vertebrae lack a comparable consistent morphology with those of Procolophon and basic statistical analyses demonstrate that these vertebrae are significantly larger than those expected in the largest known Procolophon skulls of South Africa. The morphology of these vertebra is consistent with that present in seymouriamorphs, pareiasaurs and diadectomorphs, but the absence of exclusive diagnostic characters precludes an assure assignation to either of these taxa. According to their current stratigraphic range, seymouriamorphs are the most plausible postulation, as their younger representatives are known from Late Permian deposits of Russia, but the other candidates cannot be excluded. The presence of any representative of those groups in the Sanga do Cabral Formation would be important because: (1) they would represent the first and only known record of seymouriamorphs or diadectomorphs in Gondwana, regarding the characters that the described vertebrae share with these groups; (2) they would suggest a survivorship for pareisaurs up to the Latest Permian or through the Permian-Triassic boundary, according to geochronological data currently available for this unit; (3) they might also suggest a Late Permian age for at least part of the Sanga do Cabral Formation if the intraformational conglomerates that yielded the vertebrae resulted from the rejuvenation of older levels of the same unit, and they do not include reworking of stratigraphically older strata.
... This genus was extremely widespread, however, as its remains have been found in Western Europe, Russia, India, China, Africa, Antarctica, and possibly Australia (King 1988). Lystrosaurus was traditionally considered to have first appeared in the Early Triassic, but the recent discovery of an overlap in the stratigraphic ranges of Dicynodon and Lystrosaurus has demonstrated that the latter also occurs in the Late Permian and thus it was the only dicynodont known to cross the Permo-Triassic boundary (Cheng 1993, Smith 1995, King & Jenkins 1997. ...
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... Although precise correlation to marine rocks remains uncertain, a generally accepted correlation places the Oudeberg Member of the Balfour Formation and the Cistecephalus biozone as uppermost Guadalupian, with the Dicynodon biozone encompassing the entire Lopingian (Tatarian) (Rubidge, 1995). The P-Tr boundary occurs within a zone of overlap between Dicynodon and Lystrosaurus (Hotton, 1967;Smith, 1995;King and Jenkins, 1997), as supported by recent d 13 C chemostratigraphy (MacLeod et al., 2000). King (1991) recorded 85 reptilian genera (including therapsids) from the Cistecephalus zone, 16 from the Dicynodon zone and 23 from the Lystrosaurus zone of the earliest Triassic (including new forms). ...
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Two mass extinctions brought the Paleozoic to a close: one at the end of the Guadalupian, or middle Permian (ca. 260 Ma), and a more severe, second event at the close of the Changhsingian Stage (ca. 251.6 Ma). Here we review work over the past decade that defines the probable causes of the mass extinction, and evaluate several extinction hypotheses. The marine extinctions were selective; epifaunal sus-pension feeders were more affected than other clades, although significant variations occurred even among the filter feeders. In southern China, the Changhsingian marine extinction was nearly catastrophic, occurring in 0.5 m.y. On land, vertebrates, plants, and insects all underwent major extinctions. The event coincides with (1) a drop of d 13 C in carbonates, from 2‰ to 2‰ in both marine and terrestrial sections; (2) the eruption of the massive Siberian continental flood basalts; and (3) evidence of shallow-water marine anoxia, and perhaps deep-water anoxia. Although the cause of the extinction remains unclear, a series of constraints on speculation have been established in the past few years. Leading contenders for the cause are the cli-matic effects, including acid rain and global warming, possibly induced by the erup-tion of the Siberian flood basalts; and marine anoxia. An extraterrestrial impact is consistent with the geochronological and paleontological data from southern China and elsewhere, and some possible evidence for impact has recently been advanced.
... Permian tetrapods from Zambia are best known from the Luangwa Basin, which was the subject of sporadic geological and paleontological work throughout the 20th century (Wallace, 1907;Dixey, 1937;Kitching, 1962, 1963;Attridge et al., 1964;Kemp, 1975Kemp, , 1979Davies, 1981;King, 1981;King and Jenkins, 1997;Lee et al., 1997). Based on its fossil content, the rocks of the upper member of the Madumabisa Mudstone Formation in the Luangwa Basin are considered Late Permian in age and contemporaneous with those of the Cistecephalus Assemblage Zone (AZ) of the Karoo Basin of South Africa (Angielczyk et al., 2014). ...
... Only a few genera and species are known to have survived into the earliest Triassic, including the famous, species-rich genus Lystrosaurus (i.e. in particular the species Lystrosaurus curvatus, botha & smith 2007) with an almost global distribution, and the small, perhaps burrowing Myosaurus. Lystrosaurus and its sister-taxon Kwazulusaurus (King 1997;maisch 2002;botha & smith 2007) are already known from the Late Permian of South Africa. Lystrosaurids have not been found in sediments younger than the Early Triassic. ...
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The dicynodont Sungeodon kimkraemerae n. gen. n. sp. is described on the basis of a skull from the Lower Triassic Jiucaiyuan Formation of Dalongkou (Junggar Basin, Xinjiang Uygur Autonomous Region, People's Republic of China). It is the first representative of Kannemeyeriiformes from the earliest Triassic. Kannemeyeriiforms were the predominant clade of Triassic dicynodonts, which constituted a major component of terrestrial Triassic ecosystems. The new taxon helps closing one of the most significant gaps in the fossil record of dicynodonts, since stem-kannemeyeriiforms are known from the Late Permian, whereas the first true kannemeyeriiforms previously known are late Early Triassic in age. After a phylogenetic analysis Sungeodon belongs to the family Stahleckeriidae. Therefore, the Stahleckeriidae may not have had its origin in Africa as previously assumed, but in Central Asia. More importantly, Sungeodon also suggests that the major radiation of kannemeyeriiform dicynodonts, including the emergence of all relevant subgroups of this clade, occurred not later than in the Early Triassic, soon after the end-Permian extinction. To date, only few dicynodont taxa are known from the earliest Triassic, none of which are kannemeyeriiforms. The addition of Sungeodon confirms previous predictions that our knowledge of Early Triassic dicynodont diversity and evolution is far from being complete, and that new discoveries from historically low-sampled geographic regions may fill this gap. A rapid post-extinction diversification of kannemeyeriiforms also fits with the emerging picture from other clades, such as archosaurs, of a rapid recovery from the end-Permian event in the terrestrial realm.
... It was hypothesized that Lystrosaurus principally utilized this forceful orthal bite to shear and crush resistant or fibrous vegetation, and that propaliny was less important (King and Cluver, 1991). These factors may have enabled Lystrosaurus curvatus to feed upon tough or resistant plant material, potentially facilitating its sole survivorship among dicynodonts of the Permo-Triassic extinction event (King and Jenkins, 1997;Smith and Botha, 2005). ...
... Valley, 4.8-6.4 km north of Nt'awere, Zambia (King & Jenkins, 1997 1922;Sushkin 1926;Ivakhnenko et al. 1997;Kurkin 1999;Kalandadze & Kurkin 2000;Golubev 2000;); (7) Quanzijie, Wutonggou and Guodikeng formations in the Junggur and Turpan basins, Xinjiang Province, China (Lucas 1998a(Lucas , 2001); (8) Sunan Formation, Gansu and Naobaogou Formation, Nei Monggol, both Ordos Basin, China (Lucas 1998a(Lucas , 2001Li et al. 2000); (9) north of the Mekong River in the LuangPrabang area of Laos (Battail et al. 1995;Battail 1997). ...
Article
The most extensive Permian tetrapod (amphibian and reptile) fossil records from the western United States (New Mexico-Texas) and South Africa provide the basis for definition of 10 land-vertebrate faunachrons that encompass Permian time. These are (in ascending order): the Coyotean, Seymouran, Mitchellcreekian, Redtankian, Littlecrotonian, Kapteinskraalian, Gamkan, Hoedemakeran, Steilkransian and Platbergian. These fauna- chrons provide a biochronological framework with which to determine and discuss the age relationships of Permian tetrapod faunas. Their correlation to the marine time scale and its numerical calibrations indicate that the Coyotean is a relatively long time interval of about 20 Ma, whereas most of the other faunachrons are much shorter, about 1-2 Ma long each. The Platbergian may also be relatively long, 14 Ma, although this is not certain. This suggests slow rates of terrestrial tetrapod faunal turnover during most of the Early Permian and late Middle to Late Permian, but more rapid rates of turnover during the latest Early and most of the Middle Permian, especially during the explosive initial diversification of therapsids.
... 60 m) interval of low d 13 C values De Kock & Kirschvink 2004;Ward et al. 2005;Steiner 2006) (Fig. 11). These magnetostratigraphic data indicate that the lowest occurrence of Lystrosaurus (in an interval of reversed polarity) is older than the PTB (as already suggested by King & Jenkins 1997;Kozur 1998a, b;and Botha & Smith 2007, among others), and that the highest occurrence of Dicynodon is closer to the PTB (Fig. 11). ...
Article
The Triassic timescale based on nonmarine tetrapod biostratigraphy and biochronology divides Triassic time into eight land-vertebrate faunachrons (LVFs) with boundaries defined by the first appearance datums (FADs) of tetrapod genera or, in two cases, the FADs of a tetrapod species. Definition and characterization of these LVFs is updated here as follows: the beginning of the Lootsbergian LVF = FAD of Lystrosaurus; the beginning of the Nonesian = FAD Cynognathus; the beginning of the Perovkan LVF = FAD Eocyclotosaurus; the beginning of the Berdyankian LVF = FAD Mastodonsaurus giganteus; the beginning of the Otischalkian LVF = FAD Parasuchus; the beginning of the Adamanian LVF = FAD Rutiodon; the beginning of the Revueltian LVF = FAD Typothorax coccinarum; and the beginning of the Apachean LVF = FAD Redondasaurus. The end of the Apachean (= beginning of the Wasonian LVF, near the beginning of the Jurassic) is the FAD of the crocodylomorph Protosuchus. The Early Triassic tetrapod LVFs, Lootsbergian and Nonesian, have characteristic tetrapod assemblages in the Karoo basin of South Africa, the Lystrosaurus assemblage zone and the lower two-thirds of the Cynognathus assemblage zone, respectively. The Middle Triassic LVFs, Perovkan and Berdyankian, have characteristic assemblages from the Russian Ural foreland basin, the tetrapod assemblages of the Donguz and the Bukobay svitas, respectively. The Late Triassic LVFs, Otischalkian, Adamanian, Revueltian and Apachean, have characteristic assemblages in the Chinle basin of the western USA, the tetrapod assemblages of the Colorado City Formation of Texas, Blue Mesa Member of the Petrified Forest Formation in Arizona, and Bull Canyon and Redonda formations in New Mexico. Since the Triassic LVFs were introduced, several subdivisions have been proposed: Lootsbergian can be divided into three sub-LVFs, Nonesian into two, Adamanian into two and Revueltian into three. However, successful inter-regional correlation of most of these sub-LVFs remains to be demonstrated. Occasional records of nonmarine Triassic tetrapods in marine strata, palynostratigraphy, conchostracan biostratigraphy, magnetostratigraphy and radioisotopic ages provide some basis for correlation of the LVFs to the standard global chronostratigraphic scale. These data indicate that Lootsbergian = uppermost Changshingian, Induan and possibly earliest Olenekian; Nonesian = much of the Olenekian; Perovkan = most of the Anisian; Berdyankian = latest Anisian? and Ladinian; Otischalkian = early to late Carnian; Adamanian = most of the late Carnian; Revueltian = early-middle Norian; and Apachean = late Norian-Rhaetian. The Triassic timescale based on tetrapod biostratigraphy and biochronology remains a robust tool for the correlation of nonmarine Triassic tetrapod assemblages independent of the marine timescale.
... King (1991) reported a peak in diversity of at least 85 reptilian genera in the Cistecephalus assemblage zone and 16 and 23 genera in the Dicynodon and Lystrosaurus assemblage zones, respectively. At the subzonal level, the stratigraphic distribution of only two taxa, Permian Dicynodon and Triassic Lystrosaurus, are known in detail, and their ranges overlap (Hotton, 1967;Smith, 1995;King and Jenkins, 1997). At Lootsberg Pass the two taxa apparently cooccurred during deposition of ~60 m of sediment, Dicynodon preferentially occurring in green beds and Lystrosaurus in red beds (Hotton, 1967). ...
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The rate, timing, and pattern of change in different regions and paleoenvironments are critical for distinguishing among potential causes for the Permian-Triassic (P-T) extinction. Carbon isotopic stratigraphy can provide global chronostratigraphic control. We report a large δ13C excursion at the P-T boundary and no long-term Permian δ13C trends for samples from the interior of Pangea. Stratigraphic gaps between available samples limit the resolution of our δ13C curve, but the excursion is within a 15-m-thick zone of overlap between Permian and Triassic taxa. Sedimentological and taphonomic observations demonstrate that this 15 m interval does not represent geologically instantaneous deposition. Together these data support a rapid and globally synchronous P-T event, but suggest that it occurred over a geologically resolvable interval of time.
... The upper Zechstein of the Germanic Basin below the F. eotriassica Zone, contains no conchostracans, but the succession at Dalongkou coincides well with the sections of the Tunguska Basin and the base of the Triassic at Dalongkou is therefore precisely defined (Kozur, 1998a,b). The base of the Triassic is not, as assumed earlier, situated close to the FAD of Lystrosaurus (only King and Jenkins, 1997 reported Lystrosaurus from the Permian of Zambia), but close to the LAD of Dicynodon. This latter result was confirmed by Ward et al. (2005) who reported for the Karroo Basin in South Africa that the carbon isotope minimum at the P-T boundary is situated at the LAD of Dicynodon, distinctly above the FAD of Lystrosaurus (see also MacLeod et al., 2000;Smith and Ward, 2001). ...
Article
Bulk carbonate and conodonts from three Permian–Triassic (P–T) boundary sections at Guryul Ravine (Kashmir), Abadeh (central Iran) and Pufels/Bula/Bulla (Italy) were investigated for δ13C and δ18O. Carbon isotope data highlight environmental changes across the P–T boundary and show the following features: (1) a gradual decrease of ∼4‰ to more than 7‰ starting in the Late Permian (Changhsingian) C. bachmanni Zone, with two superimposed transient positive excursions in the C. meishanensis–H. praeparvus and the M. ultima–S. ? mostleri Zones; (2) two δ13C minima, the first at the P–T boundary and a higher, occasionally double-minimum in the lower I. isarcica Zone. It is unlikely that the short-lived phenomena, such as a breakdown in biological productivity due to catastrophic mass extinction, a sudden release of oceanic methane hydrates or meteorite impact(s), could have been the main control on the latest Permian carbon isotope curve because of its prolonged (0.5Ma) duration, gradual decrease and the existence of a >1‰ positive shift at the main extinction horizon. The P–T boundary δ13C trend matches in time and magnitude the eruption of the Siberian Traps and other contemporaneous volcanism, suggesting that volcanogenic effects, such as outgassed CO2 from volcanism and, even more, thermal metamorphism of organic-rich sediments, as the likely cause of the negative trend.
... Perhaps more interesting than the topology within the genus Lystrosaurus is the fact that the 'core lystrosaurids' (i.e., Lystrosaurus and Kwazulusaurus) are nested within a larger clade that includes several former Dicynodon species in the most parsimonious cladograms from our primary analysis. This clade is supported by only two synapomorphies (ratio of length to height of the mandibular fenestra in lateral view, nasofrontal suture relatively straight, interdigitated or gently bowed), but it is noteworthy that most of the included taxa are characterized by features reminiscent of Lystrosaurus (e.g., a deepened snout and/or downturned snout, exposure of the parietals on the intertemporal skull roof) and that the specimen TSK 2 was previously identified as Lystrosaurus (King and Jenkins, 1997; see Angielczyk et al., in press, for details on why the specimen is unlikely to be Lystrosaurus). Decay support for this 'expanded' Lystrosauridae is relatively weak, and it is not consistently resolved when the continuous characters are excluded or run as discrete-state characters (this grouping is precluded when Dicynodon sensu lato is constrained to be monophyletic, although TSK 2 still groups with Lystrosaurus and Kwazulusaurus in that analysis). ...
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The dicynodont wastebasket genus Dicynodon is revised following a comprehensive review of nominal species. Most nominal species of Dicynodon pertain to other well-known dicynodont genera, especially Oudenodon and Diictodon. Of the Karoo Permian species that are referable to “Dicynodon” sensu lato, we recognize four common, valid morphospecies: Dicynodon lacerticeps, D. leoniceps, D. woodwardi, and Dinanomodon gilli, comb. nov. Eleven additional species of “Dicynodon” are recognized worldwide: D. alticeps, D. amalitzkii, D. bathyrhynchus, D. benjamini, D. bogdaensis, D. huenei, D. limbus, D. sinkianensis, D. traquairi, D. trautscholdi, and D. vanhoepeni. Morphometric analysis of D. lacerticeps and D. leoniceps specimens recovers statistically significant separation between these species in snout profile and squamosal shape, supporting their distinction. A new phylogenetic analysis of Anomodontia reveals that “Dicynodon” is polyphyletic, necessitating taxonomic revision at the generic level. D. benjamini and D. limbus are basal cryptodonts, whereas the other valid “Dicynodon” species are basal dicynodontoids. The genus Dicynodon is restricted to D. lacerticeps and D. huenei. We reinstate use of Daptocephalus, Sintocephalus, Turfanodon, Daqingshanodon, Jimusaria, and Gordonia for other species. We synonymize Vivaxosaurus permirus and Dicynodon trautscholdi (as V. trautscholdi, comb, nov.) We establish new generic names for several species formerly included in Dicynodon: Peramodon amalitzkii, comb, nov., Keyseria benjamini, comb, nov., Euptychognathus bathyrhynchus, comb, nov., Syops vanhoepeni, comb, nov., and Basilodon woodwardi, comb. nov. Of the main Karoo Permian taxa, Dicynodon, Basilodon, and Dinanomodon range throughout the Cistecephalus and Dicynodon assemblage zones, but Daptocephalus is restricted to the Dicynodon Assemblage Zone.
... high increase in daily food requirements (Kemp 2005), the endothermic metabolism might have been an advantage that enabled Lystrosaurus to survive cooler climatic conditions and to tolerate higher ambient temperature fluctuations than ectotherms. Such might have been the reason that Lystrosaurus was able to survive periods of volcanic winters at the end Permian mass extinction and could occupy a wide range of habitats with different seasonal climatic conditions (Parrish et al. 1986;Kutzbach and Gallimore 1989;King and Jenkins 1997;Ward et al. 2000) and cold winters (Crowley et al. 1989) in almost all parts of Pangaea during the Early Triassic. Thus, the first evidence of maxilloturbinal-like structures in dicynodonts also supports the hypothesis that the rapid Permian radiation and the evolutionary success of therapsids and dicynodonts were caused by a sufficiently elevated metabolic rate, activity level and regulatory abilities to occupy expanded cooler biomes than their ancestors, the pelycosaurs (Kemp 2006a). ...
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Laaß, M., Hampe, O., Schudack, M., Hoff, C., Kardjilov, N. and Hilger A. (2010). New insights into the respiration and metabolic physiology of Lystrosaurus. —Acta Zoologica (Stockholm) 92: 363–371. The first examination by neutron tomography of a skull of Lystrosaurus declivis (Therapsida, Anomodontia) from the Lower Triassic of South Africa showed complexly constructed cartilaginous maxilloturbinals in the nasal cavity. They were situated directly in the respiratory air flow and fill out most of the ventral part of the nasal chamber. Because maxilloturbinals in extant mammals and birds serve as a countercurrent exchange system for thermoregulation and humidification, their presence in the anomodont Lystrosaurus suggests strongly that Lystrosaurus was already endothermic. The endothermic metabolism allowed Lystrosaurus to tolerate high ambient temperature fluctuations. The complexly constructed maxilloturbinals could have reduced respiratory water loss because of higher ventilation rates in drought conditions in the Karoo basin.
... It was said to be aquatic, terrestrial or burrowing (King, 1991;King & Cluver, 1991;Ray et al., 2005). Specimens of Lystrosaurus have been reported from South Africa, India, Antarctica, China, Russia, and possibly Australia (King & Jenkins, 1997). In the South African Permo-Triassic Karoo Basin, this taxon was so abundant that it is used as a stratigraphic marker. ...
Article
A study on the most exhaustive taxonomic sample of amniotes (75 extant and nine extinct taxa) of any quantitative work on this topic published so far demonstrates a strong relationship between lifestyle (aquatic, amphibious or terrestrial) and humeral microanatomy. We suggest that corrections for multiple testing be used to check for statistical artefacts in the context of a phylogenetic independent contrast analysis, and we use the false discovery rate procedure for this. Linear discriminant models segregate the various lifestyles with excellent success rate of up to 98.5%. Lifestyle was thus inferred for six extinct taxa of uncertain habitat. The results obtained suggest that Captorhinus, Claudiosaurus, and Placodus were amphibious, whereas Neusticosaurus and Mesosaurus were aquatic. Lystrosaurus may have been more aquatic than previously suggested, although the results of our inference models have to be integrated with other sources of data, which suggest that it may have been amphibious, rather than aquatic (as a literal interpretation of the models would suggest). Finally, we propose an alternative method of palaeobiological inference for hypothetical ancestors. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 384–406.
... Importantly, unless the precise stratigraphical position of Brink's (1965) specimen of Cynosaurus is determined to be Triassic, no cynodont genus has been de®nitively recorded from both below and above the boundary (Smith and Ward 2001). Rubidge (1995) and King and Jenkins (1997) recorded ®ve boundary-crossing genera (Elonichthys, Lystrosaurus, Tetracynodon, Owenetta and Moschorhinus), although additional collecting has cast doubt on the latter record (Smith and Ward 2001). In addition, Reisz and Scott (2002) suggested speci®c differentiation between the Permian and Triassic members of the procolophonoid genus Owenetta. ...
Article
A new galesaurid cynodont, Progalesaurus lootsbergensis gen. et sp. nov., is described on the basis of a well-preserved skull, lower jaw, right scapula and left atlantal neural arch. Autapomorphies of Progalesaurus include postcanine teeth bearing numerous mesial and distal accessory cusps that flank a recurved main cusp, a post-temporal fenestra bordered by the squamosal ventrally and a large external naris. Progalesaurus is similar to Galesaurus in possessing a poorly defined masseteric fossa on the dentary, a strongly recurved main cusp of the postcanine dentition, an incomplete secondary palate and a similar basisphenoid-parasphenoid morphology. A cladistic analysis of ten early cynodont genera resolves a monophyletic Galesauridae encompassing Cynosaurus, Progalesaurus and Galesaurus, although support for this clade is weak. Procynosuchus and Dvinia are placed at the base of Cynodontia whereas Thrinaxodon and Platycraniellus are positioned higher, but outside of Eucynodontia. The holotype and only known specimen of Progalesaurus was collected during systematic prospecting of Permo/Triassic boundary strata at New Lootsberg Pass, Graaff-Reinet District, South Africa. The discovery of Progalesaurus increases the number of valid Early Triassic cynodonts to four and sheds light on the tempo of early cynodont diversification after the end-Permian mass extinction.
... This genus was extremely widespread, however, as its remains have been found in Western Europe, Russia, India, China, Africa, Antarctica, and possibly Australia (King 1988). Lystrosaurus was traditionally considered to have first appeared in the Early Triassic, but the recent discovery of an overlap in the stratigraphic ranges of Dicynodon and Lystrosaurus has demonstrated that the latter also occurs in the Late Permian and thus it was the only dicynodont known to cross the Permo-Triassic boundary (Cheng 1993, Smith 1995, King & Jenkins 1997. ...
Article
A rich fossil record documents nonmammalian evolution. In recent years, the application of cladistic methodology has shed valuable light on the rela-tionships within the therapsid clades Biarmosuchia, Dinocephalia, Anomodontia, and Cynodontia. Recent discoveries from South Africa suggest that Gondwana, rather than Laurasia, was the center of origin and radiation for many early therapsids. Because of their relative abundance and global distribution, therapsids have enjoyed widespread use in biostratigraphy, basin analysis, and paleo-environmental and -continental re-constructions. Synapsids (including therapsids) form the bulk of tetrapod diversity (in terms of both number of species and abundance) from Early Permian to Middle Triassic times and thus can provide critical information on the nature of the Permo-Triassic extinction in the terrestrial realm. Quantitative techniques have produced headway into understanding the relative importance of homoplasy and convergent evolution in the origin of mammals.
... Among these prime burrow-maker candidates, however, L. murrayi and L. declivis remain the most capable and probable burrowers not only based on their size, relative abundance and physiological adaptations (e.g. significant bone wall thickness in humerus, spatulate structure of the claws -for details, see King & Cluver 1991;Smith 1995;King & Jenkins 1997;Botha & Smith 2006Botha-Brink 2008), but also due to the fact that several of their articulated skeletons were found in situ in very large, scratched burrows as briefly reported by Groenewald (1991) and Retallack et al. (2003). According to Botha & Smith (2007), the difference in abundance of L. murrayi and L. declivis fossils versus other earliest Triassic fossorial taxa imply that while underground burrowing was important in escaping periods of reduced rainfall and overall climatic drying in the earliest Triassic, Lystrosaurus must have utilized other strategies of survival as well. ...
Article
Bordy, E.M., Sztanó, O., Rubidge, B.S. & Bumby, A. 2010: Early Triassic vertebrate burrows from the Katberg Formation of the south-western Karoo Basin, South Africa. Lethaia, Vol. 44, pp. 33–45.Very large (∼30–35 cm), uniform diameter cylindrical burrows were found at two localities, ∼100–110 m above Permo-Triassic boundary in the fluvial Katberg Formation (main Karoo Basin, South Africa). Analysis of their morphology and stratigraphical distribution allows us to improve both the understanding of the ethology of burrowing, and also the reconstruction of the earliest Triassic ecosystems. These burrows have a single opening that leads, via a large, uniform diameter, semi-horizontal tunnel, to a rounded terminus. These 3-m-long structures descend at angles of ∼30° to a maximum of 1.5 m depth. They are devoid of chambers, branching, cross-cutting, coiling or spiralling. Filled with coarse sediments, some have a <5-mm clay lining, and most have subtle indentations and various scratch marks. These burrows were possibly excavated as resting, hiding or aestivating shelters, and are tentatively attributed to dicynodonts (i.e. Lystrosaurus murrayi and L. declivis). Data suggest that burrowing was widespread after the P/Tr boundary event, when in this part of Gondwana, dryland fluvial systems had large fluctuations in flow with extended low-flow periods or drought punctuated by high-discharge periods. We hypothesize that these constructed refuges played a role in the biodiversity recovery and maintenance in the Early Triassic (Induan) ecosystem. □Early Triassic, Karoo Basin, Katberg Formation, South Africa, Tetrapod Burrows.
... Karoo-aged sequences are widespread in Zambia, occurring in the Luangwa, Luano and Zambezi Valleys (Fig. 1). Tetrapod fossils are however known only from the Luangwa Basin, where Wichiapingian and Chansingian tetrapod fossils from the Madumabisa Mudstone Formation correlate with the Pristerognathus-Dicynodon Assemblage Zones of South Africa (Kemp, 1976;Lee et al., 1997;King and Jenkins, 1997). This Formation is unconformably overlain by the Anisian Ntawere Formation, which correlates with the Anisian B and C subzones of the Cynognathus Assemblage Zone of South Africa . ...
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The Karoo basins of south-central Africa evolved during the first-order cycle of supercontinent assembly and breakup of Pangea, under the influence of two distinct tectonic regimes sourced from the southern and northern margins of Gondwana. The southern tectonic regime was related to processes of subduction and orogenesis along the Panthalassan (palaeo-Pacific) margin of Gondwana, which resulted in the formation of a retroarc foreland system known as the “main Karoo” Basin, with the primary subsidence mechanisms represented by flexural and dynamic loading. This basin preserves the reference stratigraphy of the Late Carboniferous–Middle Jurassic Karoo time, which includes the Dwyka, Ecca, Beaufort and Stormberg lithostratigraphic units. North of the main Karoo Basin, the tectonic regimes were dominated by extensional or transtensional stresses that propagated southwards into the supercontinent from the divergent Tethyan margin of Gondwana. Superimposed on the tectonic control on basin development, climatic fluctuations also left a mark on the stratigraphic record, providing a common thread that links the sedimentary fill of the Karoo basins formed under different tectonic regimes. As a general trend, the climate changed from cold and semi-arid during the Late Carboniferous–earliest Permian interval, to warmer and eventually hot with fluctuating precipitation during the rest of Karoo time.
... Several authors have previously proposed migration as a reason for the appearance of the post-extinction Early Triassic Karoo fauna (Kitching, 1977;King and Jenkins, 1997;Reisz et al., 2000). Pfefferkorn (1999) noted that there are often no new species in a given region after an extinction that would be capable of filling recently vacated niches, and thus, new species would have to evolve and then migrate into the area. ...
Article
The mass extinction that occurred at the end of the Permian Period approximately 251 Mya is widely accepted as the most devastating extinction event in Earth’s history. An estimated 75–90% of global diversity from both marine and terrestrial realms disappeared synchronously within at most one million and perhaps as little as 100,000 years. To date, most research has focused on the marine record and it is only recently that a few fully preserved terrestrial Permo-Triassic boundary sequences have been discovered. The main Karoo Basin of South Africa hosts several well-preserved non-marine Permo-Triassic boundary sequences that have been the focus of intensive research into the nature of the extinction and its possible causes. This study uses sedimentological and biostratigraphic data from boundary sequences near Bethulie in the southern Karoo Basin to make assumptions about the rates and timing of recovery of the terrestrial fauna in this portion of southern Gondwana after the extinction event. The biostratigraphic data gathered from 277 in situ vertebrate fossils allows us to define more accurately the temporal ranges of several taxa. These data also confirm a more precise extinction rate in this part of the basin of 54% of latest Permian vertebrate taxa, followed by the onset of a relatively rapid recovery, within an estimated 40–50 thousand years (based on the calculation of floodplain aggradation rates and compaction ratios) that included the origination of at least 12 new vertebrate taxa from amongst the survivors.
... Karoo-aged sequences are widespread in Zambia, occur- ring in the Luangwa, Luano and Zambezi Valleys (Fig. 1). Tetrapod fossils are however known only from the Luang- wa Basin, where Wichiapingian and Chansingian tetrapod fossils from the Madumabisa Mudstone Formation cor- relate with the Pristerognathus-Dicynodon Assemblage Zones of South Africa (Kemp, 1976;Lee et al., 1997;King and Jenkins, 1997). This Formation is unconformably over- lain by the Anisian Ntawere Formation, which correlates with the Anisian B and C subzones of the Cynognathus Assemblage Zone of South Africa . ...
Article
The Karoo Basin of South Africa was one of several contemporaneous intracratonic basins in southwestern Gondwana that became active in the Permo-Carboniferous (280 Ma) and continued to accumulate sediments until the earliest Jurassic, 100 million years later. At their maximum areal extent, during the early Permian, these basins covered some 4.5 million km2. The present outcrop area of Karoo rocks in southern Africa is about 300 000 km2 with a maximum thickness of some 8000 m.The economic importance of these sediments lies in the vast reserves of coal within the Ecca Group rocks of northern and eastern Transvaal and Natal, South Africa. Large reserves of sandstone-hosted uranium and molybdenum have been proven within the Beaufort Group rocks of the southern Karoo trough, although they are not mineable in the present market conditions.Palaeoenvironmental analysis of the major stratigraphic units of the Karoo succession in South Africa demonstrates the changes in depositional style caused by regional and localized tectonism within the basin. These depocentres were influenced by a progressive aridification of climate which was primarily caused by the northward drift of southwestern Gondwana out of a polar climate and accentuated by the meteoric drying effect of the surrounding land masses. Changing palaeoenvironments clearly influenced the rate and direction of vertebrate evolution in southern Gondwana as evidenced by the numerous reptile fossils, including dinosaurs, which are found in the Karoo strata of South Africa, Lesotho, Namibia and Zimbabwe.During the Late Carboniferous the southern part of Gondwana migrated over the South Pole resulting in a major ice sheet over the early Karoo basin and surrounding highlands. Glacial sedimentation in upland valleys and on the lowland shelf resulted in the Dwyka Formation at the base of the Karoo Sequence. After glaciation, an extensive shallow sea covered the gently subsiding shelf, fed by large volumes of meltwater. Marine clays and muds accumulated under cool climatic conditions (Lower Ecca Group) including the distinctive Mesosaurus-bearing carbonaceous shales of the Whitehill Formation.Subduction of the palaeo-Pacific plate reslted in an extensive chain of mountains which deformed and later truncated the southern rim of the main Karoo Basin. Material derived from these “Gondwanide” mountains as well as from the granitic uplands to the north-east, accumulated in large deltas that prograded into the Ecca sea (Upper Ecca Group). The relatively cool and humid climate promoted thick accumulations of peat on the fluvial and delta plains which now constitute the major coal reserves of southern Africa.As the prograding deltas coalesced, fluvio-lacustrine sediments of the Beaufort Group were laid down on broad gently subsiding alluvial plains. The climate by this time (Late Permian) had warmed to become semi-arid with highly seasonal rainfall. Vegetation alongside the meander belts and semi-permanent lakes supported a diverse reptilian fauna dominated by therapsids or “mammal-like reptiles”. Pulses of uplift in the southern source areas combined with possible orographic effects resulted in the progadation of two coarse-grained alluvial fans into the central parts of the basin (Katberg Sandstone Member and Molteno Formation).In the upper Karoo Sequence, progressive aridification and tectonic deformation of the basin through the late Triassic and early Jurassic led to the accumulation, in four separate depositories, of “redbeds” which are interpreted as fluvial and flood-fan, playa and dune complexes (Elliot Formation). This eventually gave way to westerly wind-dominated sedimentation that choked the remaining depositories with fine-grained dune sand. The interdune areas were damp and occasionally flooded and provided a habitat for small dinosaurs and the earliest mammals. During this time (Early Jurassic), basinwide volcanic activity began as a precursor to the break-up of Gondwana in the late Jurassic and continued until the early Cretaceous. This extrusion of extensive flood basalts (Drakensberg Group) onto the Clarens landscape eventually brought Karoo sedimentation to a close.
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Acanthotoposaurus bremneri, an early diapsid reptile from the Upper Permian Dicynodon Assemblage Zone of the Beaufort Group in South Africa's Karoo Basin, is not an archosauromorph, but is a junior subjective synonym of Youngina capensis, the most common diapsid reptile known from South African Permian sediments. This re-identification eliminates archosauromorphs from the Permian of South Africa, and reduces the number of Palaeozoic members of this group to two European taxa: Protorosaurus speneri and Archosaurus rossicus. Removal of Acanthotoposaurus from Archosauromorpha supports recent palaeobiogeographical ideas that the earliest Triassic fauna of South Africa's Lystrosaurus Assemblage Zone did not evolve in the Karoo Basin, but instead is the result of migration into the basin from other regions of Gondwana.
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In India, fossils of Lystrosaurus, a therapsid dicynodont genus, is known to occur only in the Early Triassic Panchet Formation of Raniganj Coalfield, Damodar Valley, West Bengal. The Panchet Lystrosaurus assemblage reported so far was dominated by L. murrayi and was unrepresented by L. curvatus and L. declivis. Recently, three crania, each occluded with its mandible, have been collected from the Panchet Formation. Comparative studies of the non-metric features and metric variables of the three crania reveal that two of these resemble L. curvatus and the third one is comparable with L. declivis. L. cf. curvatus described here is diagnosed by smoothly curved sagittal facial skull profile, lesser degree of snout deflection (<65°) and relatively narrower skull roof across the prefrontals and between the orbital margins in comparison to L. murrayi, L. maccaigi and L. declivis. The new find establishes that the three valid, diagnosable species of Lystrosaurus namely, L. murrayi, L. declivis and/, curvatus recognised in the Early Triassic of South Africa also existed in India and permits a better correlation of the Panchet Formation with the Katberg Formation and the upper part of the underlying Balfour Formation of the Karoo Basin of South Africa.
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Summaries of revised faunal lists are provided for fossil localities in the Kawinga Formation of the Late Permian, Songea District, Tanzania, concentrating on the dicynodont fauna. Taxonomic assignations of described dicynodonts are revised and undescribed material is determined, wherever possible. The fauna is compared with that of the ‘Daptocephalus’ (= Dicynodon Assemblage Zone) and ‘Cistecephalus’ (= Cistecephalus and Tropidostoma Assemblage Zones) (sensu Rubidge, 1995) of the South African Karoo Basin. The Kawinga Formation contains faunal elements of all three of the South African biozones. It is suggested that faunal differences between biozones in south and East Africa reflect local facies differences resulting from different tectonic regimes. The fauna of the underlying Ruhuhu Formation (= Pristerognathus Assemblage Zone) is discussed briefly, and note is taken of new discoveries from the Triassic Cynognathus Assemblage Zone of the Karoo Basin, in relation to the Kingori Sandstone and the Manda Formation of Tanzania.
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A review of the tetrapod (amphibian and amniote) record across the Permo-Triassic boundary (PTB) indicates a global evolutionary turnover of tetrapods close to the PTB. There is also a within-Guadalupian tetrapod extinction here called the dinocephalian extinction event, probably of global extent. The dinocephalian extinction event is a late Wordian or early Capitanian extinction based on biostratigraphic data and magnetostratigraphy (the extinction precedes the Illawara reversal), so it is not synchronous with the end-Guadalupian marine extinction. The Russian PTB section documents two tetrapod extinction events, one just before the dinocephalian extinction event and the other at the base of the Lystrosaurus assemblage. However, generic diversity across the latter extinction remains essentially the same despite a total evolutionary turnover of tetrapod genera. The Chinese and South African sections document the stratigraphic overlap of Dicynodon and Lystrosaurus. In the Karoo basin, the lowest occurrence of Lystrosaurus is in a stratigraphic interval of reversed magnetic polarity, which indicates it predates the marine-defined PTB, so, as previously suggested by some workers, the lowest occurrence of Lystrosaurus cannot be used to identify the PTB in nonmarine strata. Correlation of the marine PTB section at Meishan, southern China, to the Karoo basin based primarily on magnetostratigraphy indicates that the main marine extinction preceded the PTB tetrapod extinction event. The ecological severity of the PTB tetrapod extinction event has generally been overstated, and the major change in tetrapod assemblages that took place across the PTB was the prolonged and complex “replacement” of therapsids by archosaurs that began before the end of the Permian and was not complete until well into the Triassic. The tetrapod extinctions are not synchronous with the major marine extinctions at the end of the Guadalupian and just before the end of the Permian, so the idea of catastrophic causes of synchronous PTB extinctions on land and sea should be reconsidered.
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Fossil discoveries from South Africa have greatly expanded knowledge of the development of life on Earth. In particular, the enormous palaeontological wealth of the Karoo, covering a period of almost 100 million years from the Permian to the Jurassic, has enhanced understanding of the evolution of important tetrapod lineages, including mammals and dinosaurs. These fossils provide the best record of continental Permian to Jurassic faunal biodiversity, and have been crucial to studies of the global Permo-Triassic mass extinction in the continental realm, as well as giving insight into other extinction events. Recent collaborative interdisciplinary studies of stratigraphic and geographic distribution patterns of Karoo fossils have enhanced biostratigraphic resolution and global correlation of vertebrate faunas from the Permian to the Jurassic. This in turn has led to a better understanding of the biodiversity across Pangaea, and the places of origin and initial diversity of early tetrapod evolutionary lineages. Many of these originated in the southern African portion of the Gondwanan super-continent. The combination of palaeontological and sedimentological studies has led to new basin development models and solved problems which each discipline in isolation could not have achieved.
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The Kundaram Formation of the Pranhita-Godavari Valley yields the only Permian reptilian fauna in India. It is composed essentially of a dicynodont assemblage and includes Endothiodon, Cistecephalus, Pristerodon, Oudenodon and Emydops-like forms. The only non-dicynodont member is a captorhinid reptile. These taxa allow the correlation of the Kundaram Formation with the Tropidostoma and/or Cistecephalus Assemblage Zones of the Beaufort Group of South Africa, the basal beds of Madumabisa Mudstones of Zambia, the Ruhuhu and lower part of the Kawinga Formation of Tanzania and the Morro Pelado member of the Rio do Rasto Formation of Brazil, indicating a Late Permian (Tatarian) age. The Kundaram fauna helps in fixing the upper age of the coal-bearing Damuda Group more precisely at Tatarian. The distribution of the Late Permian dicynodonts in the now widely separated geographic areas suggests the close proximity of the continents and a lack of endemism or provinciality.
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In addition to their devastating effects on global biodiversity, mass extinctions have had a long-term influence on the history of life by eliminating dominant lineages that suppressed ecological change. Here, we test whether the end-Permian mass extinction (252.3 Ma) affected the distribution of tetrapod faunas within the southern hemisphere and apply quantitative methods to analyze four components of biogeographic structure: connectedness, clustering, range size, and endemism. For all four components, we detected increased provincialism between our Permian and Triassic datasets. In southern Pangea, a more homogeneous and broadly distributed fauna in the Late Permian (Wuchiapingian, ∼257 Ma) was replaced by a provincial and biogeographically fragmented fauna by Middle Triassic times (Anisian, ∼242 Ma). Importantly in the Triassic, lower latitude basins in Tanzania and Zambia included dinosaur predecessors and other archosaurs unknown elsewhere. The recognition of heterogeneous tetrapod communities in the Triassic implies that the end-Permian mass extinction afforded ecologically marginalized lineages the ecospace to diversify, and that biotic controls (i.e., evolutionary incumbency) were fundamentally reset. Archosaurs, which began diversifying in the Early Triassic, were likely beneficiaries of this ecological release and remained dominant for much of the later Mesozoic.
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Conchostracan-rich beds between the Siberian Trap flood basalts and within the thick underlying Hungtukun tuffs of the Tunguska Basin can be closely correlated with conchostracan faunas of Dalongkou (NW China) and the Germanic Basin. The Germanic Basin faunas in turn can be closely correlated with the marine international stratigraphic time scale, and the accuracy of the biostratigraphic correlation of the Permian–Triassic boundary (PTB) is confirmed by a minimum in δ 13 C carb values at this level. These high-resolution correlations demonstrate conclusively that the PTB is located within the temporally brief but thick Siberian Trap flood basalt sequence. The PTB lies slightly above the level of the main Permo-Triassic extinction event in low latitude marine beds, which occurred at the base of the C. meishanensis–H. praeparvus conodont zone and correlates with the beginning of the Siberian Trap flood basalt event. The main end-Permian continental extinction event was somewhat earlier, within the middle of the C. changxingensis–C. deflecta conodont zone. This horizon marks a mass extinction that devastated a diverse conchostracan fauna and left only low diversity faunas at low and high latitudes. This continental extinction event horizon lies within the middle of the Hungtukun tuffs of the Tunguska Basin and 107 m above the base of the Guodikeng Formation at Dalongkou (NW China). A "Triassic type" pioneer flora with numerous lycopod spores appears immediately above this level. Severe high northern and southern latitude marine extinctions occurred concurrently with this continental event, but low latitude marine biota was not then affected. This earlier event is best explained by global warming. The main low latitude extinction event in marine warm water faunas occurred somewhat later and left no signature in high latitude marine faunas or in continental faunas, but it does coincide with a rapid collapse of tropical rain forest environments (disappearance of the highly diverse Gigantopteris flora). This collapse likely was caused by global cooling due to a volcanic winter event. Published by Elsevier B.V.
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Conchostracans or clam shrimp (order Conchostraca Sars) are arthropods with a carapace consisting of two chitinous lateral valves. Triassic conchostracans range in size from 2 to 12.5 mm long and are common in deposits that formed in fresh water lakes, isolated ponds and brackish areas. Their dessication-and freeze-resistant eggs can be dispersed by wind over long distances. Therefore many conchostracan species are distributed throughout the entire north-ern hemisphere. In the Late Permian to Middle Triassic interval, several of these forms are also found in Gondwana. Many wide-ranging conchostracan species have short stratigraphic ranges, making them excellent guide forms for subdivision of Triassic time and for long-range correlations. The stratigraphic resolution that can be achieved with conchostracan zones is often as high as for ammonoid and conodont zones found in pelagic marine deposits. This makes con-chostracans the most useful group available for biostratigraphic subdivision and correlation in continental lake deposits. Upper Triassic Gondwanan conchostracan faunas are different from conchostracan faunas of the northern hemisphere. In the Norian, some slight provincialism can be observed even within the northern hemisphere. For example, the Sevatian Redondestheria seems to be restricted to North America and Acadiestheriella n. gen. so far has been found only in the Sevatian deposits from the Fundy Basin of southeastern Canada. Here we establish a con-chostracan zonation for the Changhsingian (Late Permian) to Hettangian (Early Jurassic) of the northern hemisphere that, for the most part, is very well correlated with the marine scale. This zona-tion is especially robust for the Changhsingian to early Anisian, late Ladinian to Cordevolian and Rhaetian to Hettangian intervals. For most of the Middle and Upper Triassic, this zonation is still preliminary. Five new genera, six new species and a new subspecies of conchostracans are described that are stratigraphically important. Half of the eight stage boundaries of the Triassic have been defined by a bio-event within a marine Global Stratotype and Point (GSSP) locality, and these definitions have been accepted by both the International Subcommission on Triassic Stratigra-phy and the International Commission on Stratigra-phy. The remaining four stage boundaries are nearing final definition. In the Lower Triassic, both the base of the Induan (priority: Brahmanian) Stage (¼ base of Triassic) and the base of the next younger Olenekian Stage have been firmly defined. In the Middle Triassic, there is wide agree-ment that the defining species for the base of the Anisian Stage should be Chiosella timorensis in the GSSP candidate site at Desli Caira (Romania), but there has not yet been a formal vote on this. The base of the overlying Ladinian Stage, however, has been firmly defined. In the Upper Triassic, the base of the Carnian has been firmly likewise defined, but there is not yet a final defi-nition for the boundaries of the overlying Norian and Rhaetian stages. A consensus has not been reached on a defining species for the base of the Norian or its GSSP locality, but all of the different proposals under consideration do at least fall within a rather narrow stratigraphic interval. For the base of the Rhaetian, Misikella posthernsteini Kozur & Mock has been chosen as the defining species by the International Working Group on the Rhaetian stage, and the GSSP candidate locality at Steinbergkogel (Austria) has been studied in detail by a group under the leadership of L. Krystyn (Vienna) and presented to the participants of the International Conference on 'Upper Triassic Sub-divisions, Zonations and Events' in Bad Goisern in the autumn of 2008. The base of the overlying Hettangian stage (¼ base of the Jurassic) has been defined (so far only by a working group) as the FAD (First Appearance Datum) of Psiloceras spelae Guex, Taylor, Rakus & Bucher. The final definition of the Triassic stages within marine GSSP sections will be completed in the near future, but more than 50% of known Triassic rocks are of continental origin. Therefore, the main task of Triassic stratigraphers in the future will be subdivid-ing and correlating terrestrial strata, both between
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