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Here we examine the bone histology of multiple skeletal elements of three individuals of Jonkeria from the middle Permian Tapinocephalus Assemblage Zone of the Karoo Basin of South Africa. Our histological results reveal a predominance of highly vascularized, uninterrupted fibrolamellar bone tissue, which suggests rapid periosteal bone deposition and an overall fast growth. However, in a rib, the periosteal bone deposition periodically stops abruptly, resulting in the deposition of several lines of arrested growth. The absence of bone growth marks in the limb bones (except for an annulus in a radius) suggests a young ontogenetic status for all specimens of the studied sample. All the skeletal elements are characterized by thick bone walls, extensive secondary reconstruction and the complete infilling of the medullary cavity by bony trabeculae. The latter condition is different to observations of contemporaneous graviportal terrestrial pareiasaurs, but similar to the observations in the modern semi-aquatic Hippopotamus, and suggests a possible semi-aquatic lifestyle for Jonkeria. On the basis of our histological findings, we assert that during early ontogeny Jonkeria experienced rapid sustained rates of growth, whereas later in ontogeny they experienced cyclical rates of growth.

Fossil wood is described from the Late Permian Middleton Formation, Adelaide Subgroup, Beaufort Group of the Karoo Supergroup in the Easter Cape Province, South Africa. The wood consists of in situ tree trunks up to 9 m long, partially enclosed in fine-grained sandstone surrounded by argillaceous mudstone and siltstone. The strata are poorly exposed due to the eroded and denuded land surface. All are lying horizontally and none are in upright growth positions. Comparisons of the study site lithologies with known surrounding Middleton Formation lithostratigraphy supports the interpretation that the palaeoenvironment responsible for the transport and deposition of the fossil wood was fluvial, with sandstone representing in-channel deposits and the mudstone-siltstone flood plain sequences where the trees were originally located before being uprooted and transported within the channels. Thin sections of twenty-nine wood samples revealed the presence of four existing taxa, Agathoxylon africanum, Agathoxylon karooensis, Australoxylon natalense and Australoxylon teixeirae. Growth rings of all the samples show a wide range of ring width from 1 mm to 11 mm, indicating growth under suitable climatic regimes with adequate water supply interspersed by very wet and warm periods. Crushed earlywood, s-shaped cell walls and torn cell walls suggest felling of trees during storm and/or flood events followed by sedimentary transport in palaeochannels prior deposition within the channel sands.

The Cynognathus Assemblage Zone is the youngest tetrapod biozone of the Beaufort Group (Tarkastad Subgroup, Karoo Supergroup). It is situated between the underlying Lystrosaurus declivis Assemblage Zone and the base of the overlying Molteno Formation (Stormberg Group) and corresponds to the entire Burgersdorp Formation. It is characterised by the presence throughout of the cynodont genus Cynognathus. The biozone reaches a maximum thickness of around 650 m in the southeast part of the basin and thins dramatically to the north, where it is only a maximum of 50 m thick. We here propose a three-fold subdivision into a lower Langbergia-Garjainia Subzone, a middle Trirachodon-Kannemeyeria Subzone and an upper Cricodon-Ufudocyclops Subzone. The basal contact is defined biostratigraphically by the first appearance of Cynognathus crateronotus and Langbergia modisei. The Cynognathus Assemblage Zone lacks a defined biostratigraphic upper limit, being unconformably terminated by the base of the overlying Molteno Formation, which lacks a terrestrial vertebrate fossil record other than trackways.

The name Daptocephalus Assemblage Zone (DaAZ) is re-instated for vertebrate assemblages of the uppermost Permian strata (Balfour, upper Teekloof, and Normandien formations) of South Africa’s main Karoo Basin (MKB). This involved taxonomic revision of the dicynodontoid “Dicynodon” sensu lato, reviving Daptocephalus leoniceps, and revising the stratigraphic ranges of co-occurring index taxa (Theriognathus microps, Procynosuchus delaharpeae) of the Dicynodon Assemblage Zone (DiAZ) as it was known. This work has demonstrated the appearance of index taxa below the stratigraphically defined DiAZ. Moreover, the first appearance of Lystrosaurus maccaigi and Moschorhinus kitchingi in the upper reaches of the biozone calls for the establishment of a two-fold subdivision of the current DaAZ into lower (Dicynodon-Theriognathus) and upper (Lystrosaurus maccaigi-Moschorhinus) subzones. The biostratigraphic utility of Daptocephalus and other South African dicynodontoids outside of the MKB is limited due to basinal endemism at the species level and varying temporal ranges of dicynodontoids globally. Accordingly, their use is recommended only for correlation within the Karoo Basin at this stage.

The Endothiodon Assemblage Zone is the third oldest tetrapod biozone of the Beaufort Group (Adelaide Subgroup, Karoo Supergroup). It is situated between the underlying Tapinocephalus and overlying Cistecephalus assemblage zones and in the southwestern part of the basin corresponds to the majority of the Poortjie and Hoedemaker members of the Teekloof Formation. It is characterised by the dicynodont genus Endothiodon, especially in the lower part of assemblage zone, and records early ecosystem recovery from the Capitanian mass extinction. It also contains the lowest occurrence in the Karoo Basin of cynodont therapsids, eutherocephalians, bidentalian dicynodonts, and diapsids. The biozone reaches a maximum thickness of around 250 m in the southwestern part of the basin. We propose a two-fold subdivision into a lower Lycosuchus - Eunotosaurus Subzone (equivalent to the upper two-thirds of the former Pristerognathus Assemblage Zone) and an upper Tropidostoma - Gorgonops Subzone (equivalent to the former Tropidostoma Assemblage Zone), with the contact defined by the first appearance of Tropidostoma dubium. The Endothiodon Assemblage Zone is terminated by the first appearance of Aulacephalodon bainii.

The Tapinocephalus Assemblage Zone is the second oldest tetrapod biozone of the Beaufort Group (Adelaide Subgroup, Karoo Supergroup), biostratigraphically positioned between the underlying Eodicynodon and overlying Endothiodon assemblage zones. It is characterised by a rich fossil tetrapod assemblage comprising basal members of most therapsid clades, but particularly dinocephalians such as Moschops capensis and basal pareiasaurs such as Bradysaurus in co-occurrence with the pylaecephalid dicynodonts Robertia and Eosimops. It corresponds to the upper two thirds of the Abrahamskraal Formation, is Capitanian (Guadalupian) in age, and reaches a maximum thickness of around 1500 m. The biozone is here separated into two subzones: a lower Eosimops – Glanosuchus Subzone and an upper Diictodon – Styracocephalus Subzone. The contact between the two subzones is defined by the first appearance of Diictodon feliceps, which closely corresponds to the base of the Moordenaars Member. The uppermost part of the biozone contains the Capitanian mass extinction and the low diversity fauna in its immediate aftermath. The zone is terminated by the first appearance of Endothiodon bathystoma.

The late Permian (Lopingian) Cistecephalus Assemblage Zone (CiAZ) of the Karoo Supergroup in South Africa has recently been radiometrically-dated to range from 256 to 255 My. It encompasses approximately one million years of the late Wuchiapingian epoch, at a time when the ancient intra-continental lowlands of southern Gondwana had fully recovered from the end-Guadalupian mass extinction. The diverse Cistecephalus Assemblage Zone fauna is dominated by the small herbivorous dicynodonts Diictodon, Pristerodon and the molelike Cistecephalus, along with a range of larger dicynodont herbivores including Oudenodon, Aulacephalodon, Rhachiocephalus, Dinanomodon and rare Endothiodon. The attendant large carnivores include the gorgonopsians Aelurognathus, Rubidgea, and Smilesaurus, while smaller carnivores are represented by eutherocephalians (e.g., Ictidosuchoides, Ictidosuchops) and small gorgonopsians (e.g., Aloposaurus, Scylacocephalus). Of the parareptiles, the large-bodied taxon Pareiasaurus is most common, with the diminutive pareiasaurs Anthodon, Nanoparia, and Pumiliopareia making their first appearance. Lithostratigraphically, the biozone for the most part coincides with the arenaceous Oukloof and lower Steenkampsvlakte members in the western sub-basin and the equivalent Oudeberg and lower Daggaboersnek members in the east, where it reaches its maximum thickness of 300 m. The Cistecephalus Assemblage Zone thins westwards to 120 m at Teekloof Pass, and eastwards to approximately 100 m near the town of Fort Beaufort.

The Karoo Supergroup of South Africa, internationally renowned for its almost continuous Carboniferous to Jurassic record of deposition in a foreland basin setting, hosts an unparalleled record of fossil tetrapods that provides unique insight into terrestrial biodiversity change over this extended period. Understanding of the litho-, bio- and chronostratigraphy of the Karoo Basin has greatly improved in recent years but most work has focused on the thicker and better-exposed rocks in the basinal foredeep . A core issue that has remained ambiguous is the stratigraphic placement of the diachronous Ecca-Beaufort contact, for which different criteria have been used during mapping in different parts of the main Karoo Basin. Comparison of biostratigraphy and contrasting lithological facies changes with those in the better-studied foredeep enabled us to revise the lithostratigraphy of the Ecca and Beaufort groups in the distal part of the main Karoo Basin. The presence of proximal marine facies associations in the distal sector conform with the definition of the Waterford Formation of the Ecca Group, so far recognised only in the southern foredeep. The upper contact of the Waterford Formation represents a change from a subaqueous to a subaerial delta plain depositional environment and marks the boundary between the Ecca and Beaufort groups, as in the south. This has consequences for Beaufort Group stratigraphic subdivision in the distal sector of the Karoo foreland basin.

The Beaufort Group of the main Karoo Basin of South Africa records two major extinction events of terrestrial vertebrates in the late Palaeozoic. The oldest of these has been dated to the late Capitanian and is characterized by the extinction of dinocephalian therapsids and bradysaurian pareiasaurs near the top of Tapinocephalus Assemblage Zone. Faunal turnover associated with the extinction of dinocephalians is evident in vertebrate faunas from elsewhere in Pangaea but it can be best studied in the Karoo Basin, where exposures of the upper Abrahamskraal and lower Teekloof formations allow continuous sampling across the whole extinction interval. Here we present field data for several sections spanning the Capitanian extinction interval in the southwestern Karoo and discuss recent work to establish its timing, severity, and causes. A large collections database informed by fieldwork demonstrates an increase in extinction rates associated with ecological instability that approach that of the end-Permian mass extinction, and shows significant turnover followed by a period of low diversity. Extinctions and recovery appear phased and show similarities to diversity patterns reported for the end-Permian mass extinction higher in the Beaufort sequence. In the Karoo, the late Capitanian mass extinction coincides with volcanism in the Emeishan Large Igneous Province and may have been partly driven by short-term aridification, but clear causal mechanisms and robust links to global environmental phenomena remain elusive.

Detrital zircon U-Pb age dating was used for provenance determination and maximum age of deposition for the Upper Permian (upper Teekloof and Balfour formations) and Lower Triassic (Katberg Formation) lithostratigraphic subdivisions of the Beaufort Group of South Africa's Karoo Basin. Ten samples were analysed using laser ablation - single collector - magnetic sectorfield - inductively coupled plasma - mass spectrometry (LA-SF-ICP-MS). The results reveal a dominant Late Carboniferous-Late Permian population (250 ± 5 Ma – 339 ± 5 Ma), a secondary Cambrian-Neoproterozoic (489 ± 5 Ma to 878 ± 24 Ma) population, a minor Mesoproterozoic (908 ± 24 Ma to 1308 ± 23) population, and minor occurrences of Devonian, Ordovician, Proterozoic and Archean zircon grains. Multiple lines of evidence (e.g. roundness and fragmentary nature of zircons, palaeo-current directions, and previous work), suggest the older zircon populations are related to sedimentary recycling in the Gondwanide Orogeny. The youngest and dominant population contain elongate euhedral grains interpreted to be directly derived from their protolith. Since zircons form in felsic igneous rocks, and no igneous rocks of Late Permian age occur in the Karoo Basin, these findings suggest significant input of volcanic material by ash falls. These results support sedimentological and palaeontological data for a Lopingian (Late Permian) age for the upper Beaufort Group, but contradict previous workers who retrieved Early Triassic dates from zircons in ashes for the Beaufort and Ecca Groups. Pb-loss not revealed by resolvable discordance on the concordia diagram, and metamictization of natural zircons are not factored into the conclusions of earlier workers.

Important palaeoenvironmental differences are identified during deposition of the latest Permian Daptocephalus Assemblage Zone (DaAZ) of the South African Beaufort Group (Karoo Supergoup), which is also divided into a Lower and Upper subzone. A lacustrine floodplain facies association showing evidence for higher water tables and subaqueous conditions on the floodplains is present in Lower DaAZ. The change to well-drained floodplain facies association in the Upper DaAZ is coincident with a faunal turnover as evidenced by the last appearance of the dicynodont Dicynodon lacerticeps , the therocephalian Theriognathus microps , the cynodont Procynosuchus delaharpeae , and first appearance of the dicynodont Lystrosaurus maccaigi within the Ripplemead member. Considering the well documented 3-phased extinction of Karoo tetrapods during the Permo-Triassic Mass Extinction (PTME), the facies transition between the Lower and Upper DaAZ represents earlier than previously documented palaeoenvironmental changes associated with the onset of this major global biotic crisis.

Cynognathus crateronotus is a species of large carnivorous cynodont, first named and best known from the Triassic Burgersdorp Formation (Beaufort Group, Karoo Basin) of South Africa. Fossils of the genus have also been reported from the upper Fremouw Formation of Antarctica, the Upper Omingonde Formation of Namibia, and the Rio Seco de la Quebrada Formation of Argentina. Without associated cranial material, however, distinguishing the postcrania of Cynognathus from that of the closely related cynognathian, Diademodon tetragonus, has proven difficult. Here we provide a more comprehensive diagnosis for Cynognathus crateronotus and describe two novel occurrences. First, parts of a medium-sized individual were recovered from a scrambled mass of dental and semiarticulated postcranial material from the lower Ntawere Formation of Zambia, a horizon that previously produced fossils of Diademodon and Kannemeyeria. Second, a large individual was collected from a recently discovered locality within the lower part of the Lifua Member of the Manda Beds of Tanzania. A large proportion of the postcranial skeleton, along with some craniodental remains, was found ex situ in a sandy streambed just downstream from a quarry that has produced the dicynodont Dolichuranus, an azendohsaurid archosauromorph, and the avemetatarsalian Teleocrater rhadinus. The widespread occurrence of Cynognathus across southern Pangea demonstrates its utility as a biostratigraphic marker, but recently published radiometric age estimates from Argentina suggest that either the genus persisted for over 10 million years or African strata traditionally interpreted as Middle Triassic are better understood as Late Triassic in age.

The gorgonopsian genus Arctops from the late Permian of South Africa is revised and redescribed. The nominal species Arctops kitchingi and Arctops watsoni are found to be junior synonyms of the type species Arctops willistoni. A well-prepared specimen previously referred to Lycaenops angusticeps and additional, previously undescribed specimens are also referred to A. willistoni. The vomerine morphology of Arctops is highly distinctive, supporting previous work highlighting the taxonomic importance of this element. Arctops is restricted to the Cistecephalus Assemblage Zone of the South African Beaufort Group. Inclusion of Arctops in a phylogenetic analysis of gorgonopsian relationships recovers it as the sister-taxon of Smilesaurus ferox, with the clade composed of Arctops + Smilesaurus positioned outside the Rubidgeinae.

A new lithostratigraphic framework is introduced for the Permian Balfour and upper Teekloof formations (lower Beaufort Group) in the main Karoo Basin of South Africa. The Balfour Formation’s Barberskrans Member (BM) is identified as the Oudeberg Member at its current type location. Thus the BM requires renaming, and is here defined as the Ripplemead member (RM) after Ripplemead farm 20 km north of Nieu Bethesda. The upper Teekloof Formation is subdivided into the sandstone-poor Steenkampsvlakte Member and sandstone-rich Javanerskop member which occurs in the highest points of the western escarpment between Beaufort West and Fraserburg. The thickness of the Balfour Formation does not significantly change from east to west, but thins rapidly northwards to a point where the Oudeberg Member is not present, and other subdivisions are much attenuated. Recent biostratigraphic revisions of Lopingian tetrapod fauna show the Ripplemead and Javanerskop members are not contemporaneous. Therefore, no lithostratigraphic members in the Upper Permian Beaufort Group have basin wide distribution, and it is recommended that they be used as local markers only in conjunction with other proxies (e.g. biostratigraphic and chronostratigraphic markers). Patterns of biostratigraphic disappearance of tetrapods in the Balfour Formation at the same stratigraphic interval throughout the basin despite the thinning of strata northward, supports a temporally phased terrestrial Permo-Triassic mass extinction (PTME). The lack of basin wide lithostratigraphic markers highlights the variable aggradation rates during the deposition of the Beaufort Group caused by foreland tectonics and localised subsidence. A need for a full consideration of these complexities and their effects on the fossil records is therefore required in determining whether the terrestrial PTME is synchronous with the marine extinction.

A 2.5D gravity modelling along seven selected profiles that covers the Western Cape Province of South Africa was carried out to deduce the depositional surface and isochore (true vertical) thickness of the Dwyka, Ecca and Beaufort Group sediments. The results revealed that the Karoo Basin deepens to a depth of about 4600 m in the south-western region, near the front of the Cape Fold Belt. Also, the model gives indication that the Karoo dolerite intrusions are interconnected at depth and are mostly concentrated at the centre of the basin. The isochore thickness maps show that the Beaufort Group is the thickest group in the Karoo Supergroup, with a maximum thickness of about 6046±277 m, followed by the Ecca and Dwyka Groups with thicknesses of around 3720±183 m and765±69 m, respectively. The maximum depositional surface (elevation) for the Dwyka, Ecca and Beaufort sediments are approximately 1696 m, 1247 m and 1491 m, respectively, whereas the maximum depth below sea level are around 3668 m, 3209 m and 480 m, respectively. Furthermore, the isochore thickness maps indicate that the Ecca Group, which is the main target for hydrocarbon exploration in the Karoo, thickens toward the south, away from the centre of the basin and reaches thickness of greater than 3680 m. The correlation of the depositional surfaces with the isochore thickness maps revealed that the sediments in structural high areas were subsided, eroded and deposited in structural low areas. Consequently, the structural low areas are characterised by thick sediments cover and vice versa., Gravity modelling; Isochore thickness; Depositional surface; Karoo Basin.

An aquifer in the semi-arid environment of Sutherland, South Africa is examined. The characterization of the saturated geological unit was completed by mapping associated dolerite dykes and fractured outcrops of Beaufort Group sedimentary rocks. This was complimented by pumping tests in order to better understand the fracture connectivity that was found to decrease with distance from a prominent dyke. Groundwater samples and precipitation samples in the study area were analysed for stable isotopes. Drill chips of selected boreholes were examined in order to also better understand the nature of the subsurface at the contact of the dolerite and a suspected subsurface feature identified through satellite imagery. The results are combined into a conceptual geohydrological model to gain insight into the groundwater flow dynamics of the area. Findings suggest preferential recharge occurs in the study area with higher hydraulic infiltration related to the river beds and fracture sets in the study area.

The Kalahari Karoo Basin of Botswana is an intracratonic basin developed in south-central Gondwana and is filled with Upper Carboniferous–Lower Jurassic Karoo Supergroup volcano-sedimentary units. The Karoo Supergroup units are unconformably covered by the Cretaceous to recent Kalahari Group. The Upper Karoo Supergroup in the Central Kalahari Karoo Sub-Basin of Botswana consists of the lacustrine sediments of the Beaufort Group (Tlhabala Formation), overlaid unconformably by the continental sediments of the Lebung Group, and by the continental basalts of the Stormberg Group. The Late Triassic to Early Jurassic Lebung Group is subdivided into the Mosolotsane Formation and the Ntane Formation. This sedimentary sequence is poorly exposed, and formation boundaries are tentatively identified by lithological changes in boreholes. Here, new sedimentological and geochemical data are used for the refinement of the stratigraphy of the Upper Karoo Supergroup in the Central Kalahari Karoo Sub-Basin of Botswana, new criteria for the identification of unit boundaries are set and provenance of the Lebung Group sediments has been defined. The geochemical investigation of the Upper Karoo Supergroup in the Central Kalahari Karoo Sub-Basin of Botswana revealed clear geochemical markers that have allowed the pinpointing of unit boundaries between the Tlhabala Formation (Beaufort Group), Mosolotsane Formation (lowermost Lebung Group). The sediments from the Tlhabala Formation have a geochemical signature typical of wackes, while the sandstones from the overlying Mosolotsane Formation and the Ntane Formation are dominated by arkose to subarkose. The transition from wacke to subarkose pinpoints the boundary between the Beaufort Group and the base of the Lebung Group. The Tlhabala Formation is characterized by increasing SiO2/Al2O3 ratio, with a maximum at the base of the Lebung Group, and by an upward decrease in the abundance of Na, K and transition metals such as Cr, Mn and Fe. The SiO2/Al2O3 ratio decreases upward in the Lebung Group. Similarly, the abundances of Na, K, Cr, Mn and Fe slightly increase upward only to show a negative peak at the Lebung Group and the Kalahari Group boundary. This contact is marked by a clear increase in the total REE content. The chemical composition of the Lebung Group sandstones also indicates a quartzose sedimentary provenance. The CIA (chemical index of alteration) values for these sandstones ranged from 63 to 73, indicating a high degree of chemical weathering. This type of intense weathering should produce high volumes of clay minerals, which are rather scarce in the studied samples. This indicates that the large amount of quartz in the Lebung Group has been recycled from the Paleoproterozoic sedimentary sequences of the Palapye Group, located southeast from the study area.

Biarmosuchia is a clade of basal therapsids that includes forms possessing plesiomorphic ‘pelycosaurian’ cranial characters as well as the highly derived Burnetiamorpha which are characterised by cranial pachyostosis and a variety of cranial bosses. Potential ontogenetic variation in these structures has been suggested based on growth series of other therapsids with pachyostosed crania, which complicates burnetiamorph taxonomic distinction and thus it is essential to better understand cranial ontogeny of the Burnetiamorpha. Here, three new juvenile biarmosuchian skulls from the late Permian of South Africa are described using X-ray micro computed tomography (CT). We found that juvenile biarmosuchians are distinguished from adults by their relatively large orbits, open cranial sutures, and incomplete ossification of the braincase and bony labyrinth. Also, they manifest multiple centres of ossification within the parietal and preparietal bones. CT examination reveals that the holotype of Lemurosaurus pricei (BP/1/816), previously alleged to be a juvenile, shows no evidence of juvenility and is thus probably an adult. This suggests that the larger skull NMQR 1702, previously considered to be an adult L. pricei, may represent a new taxon. This study provides, for the first time, a list of characters by which to recognise juvenile biarmosuchians.

The Dicynodon Assemblage Zone (DiAZ) of South Africa's Karoo Basin is one of the eight biostratigraphic zones of the Beaufort Group. It spans the uppermost Permian strata (Balfour, Teekloof, and Normandien formations) and traditionally has been considered to terminate with the disappearance of Dicynodon lacerticeps at the Permo-Triassic Boundary. We demonstrate that the three index fossils currently used to define the Dicynodon Assemblage Zone ( Dicynodon lacerticeps , Theriognathus microps , and Procynosuchus delaharpeae ) have first appearance datums (FADs) below its traditionally recognized lower boundary and have ranges mostly restricted to the lower portion of the biozone, well below the Permo-Triassic Boundary. We propose re-establishing Daptocephalus leoniceps as an index fossil for this stratigraphic interval, and reinstating the name Daptocephalus Assemblage Zone (DaAZ) for this unit. Furthermore, the FAD of Lystrosaurus maccaigi in the uppermost reaches of the biozone calls for the establishment of a two-fold subdivision of the current Dicynodon Assemblage Zone. The biostratigraphic utility of Da. leoniceps and other South African dicynodontoids outside of the Karoo Basin is limited due to basinal endemism at the species level and varying temporal ranges of dicynodontoids globally. Therefore, we recommend their use only for correlation within the Karoo Basin at this time. Revision of the stratigraphic ranges of all late Permian tetrapods does not reveal a significant change in faunal diversity between the lower and upper DaAZ. However, the last appearance datums of the abundant taxa Di. lacerticeps , T. microps , P. delaharpeae , and Diictodon feliceps occur below the three extinction phases associated with the end-Permian mass extinction event. Due to northward attenuation of the strata, however, the stratigraphic position of the extinction phases may need to be reconsidered.

Various different models have been proposed for the style of fill of the Karoo Basin in South Africa. One of these proposes that the Karoo Basin behaved as a partitioned entity, with reciprocal fills on either side of a hinge line separating proximal and distal facies. Detailed sedimentological, palaeontological, stratigraphic and geophysical data for the Beaufort Group in the central Free State lends credence to this model. In the study area fossils assignable to the Dicynodon , Lystrosaurus and Cynognathus assemblage zones occur in the Balfour, Katberg and Burgersdorp formations respectively. This data shows that certain parts of the Beaufort Group stratigraphic succession that are present in the southern part of the Karoo Basin, are absent in the central Free State, indicating either a depositional hiatus or a period of erosion at the beginning and the end of Lystrosaurus Assemblage Zone, as well as the end of Cynognathus Assemblage Zone times. During these depositional hiatuses or periods of erosion, deposition or preservation of the rock record was restricted to the proximal sector (south of the hinge line). Study of the geophysical data has also allowed for the definition of a basement high north-east of Thaba Nchu, which probably accounts for the provenance of the informally named Musgrave unit (upper Balfour Formation), which also has an anomalous south-westerly palaeocurrent direction.

A new temnospondyl is described from the Middle–Upper Permian sequence of the Paraná Basin (Rio do Rasto Formation) in southern Brazil. The material consists of disarticulated cranial and postcranial elements, preserved in association. The cranial elements include part of the orbital region of the skull roof, the basicranium, a number of endocranial elements, stapes and a right hemimandible. The postcranial elements include vertebrae, ribs, pectoral girdle elements, a right femur and a cluster of scales. The new species displays a rhinesuchid pattern, which is similar to the South African rhinesuchids from the Upper Permian Beaufort Group of the Karoo Basin, but differs from them by the presence of a robust and elongated epipterygoid with a blade-like anterior process in addition to elongated and deeper muscular pockets on the parasphenoid, which allow the assignment of this specimen to a new species. However, the phylogenetic analysis grouped the material described herein and Australerpeton cosgriffi inside Stereospondylomorpha, in a transitional position between the Laurasian assemblages and South African temnospondyls. This result supports a connection between the Brazilian and Eastern European Permian fauna and provides important data for future biostratigraphic studies.

We studied three partially overlapping sections with a composite thickness of ∼600 m in the upper Permian fluvial siltstones and fine-grained sandstones of the Abrahamskraal Formation, the basal unit of the Beaufort Group, in the Karoo Basin of Western Cape Province, South Africa. Paleomagnetic analysis reveals three components of Natural Remanent Magnetization (NRM). Heating to ∼180°C removes a remanent magnetization parallel to the present-day field, which is interpreted as a viscous overprint. An intermediate unblocking temperature component is removed by heating to 450°C; this direction is always of normal polarity and is identical to a regional overprint imparted during the Early Jurassic emplacement of the Karoo Large Igneous Province. A high-temperature component isolated above 450°C is of dual polarity and is interpreted as primary on the basis of a positive reversals test. The virtual geomagnetic pole position for the Abrahamskraal Formation computed from the average high-temperature characteristic remanent magnetization direction is in agreement with the late Permian directions for stable Gondwana and with previous results from the lowermost Abrahamskraal Formation and Waterford Formation at the Ouberg Pass section. The predominantly normal polarity of this magnetization is in agreement with either a middle-late Lopingian age (ca. 254–256 Ma) or a late Guadalupian age (ca. 262 Ma) according to the global geomagnetic polarity time scale. We integrate these new results with existing magnetostratigraphic, biostratigraphic, and geochronological results from the Karoo Basin, with particular emphasis on the controversy over zircon age data reported from the underlying Ecca Group.

The middle (?) to upper Permian Emakwezini Formation is part of the lower Beaufort Group (Karoo Supergroup) in the Lebombo Basin in the eastern part of South Africa. The unit is highly significant both palaeobotanically and economically due to its plant-rich carbonaceous mudstones and multiple semi-anthracite to anthracite seams that range in thickness from

The dinocephalians (Synapsida, Therapsida) were one of the dominant tetrapod groups of the Middle Permian (Guadalupian Epoch, ~270–260 million years ago) and are most abundantly recorded in the Tapinocephalus Assemblage Zone (AZ) of the Main Karoo Basin, South Africa. Dinocephalians are thought to have become extinct near the top of the Abrahamskraal Formation of the Beaufort Group and their disappearance is one criterion used to define the base of the overlying Pristerognathus AZ. Because of the abundance of fossils in the Karoo, the Beaufort Group biozones form the biostratigraphic standard for later Permian terrestrial tetrapod ecosystems, so their stratigraphic delineation is of great importance to Permian palaeobiology. We report two new specimens of the rare tapinocephalid dinocephalian Criocephalosaurus from the lowermost Poortjie Member, which makes them the youngest dinocephalians known from the Main Karoo Basin and extends the Tapinocephalus AZ from the Abrahamskraal Formation up into the Teekloof Formation. The extension of the Tapinocephalus AZ relative to the lithostratigraphy potentially affects the biozone or biozones to which a fossil species can be attributed; this extension has implications for biostratigraphic correlations within the Main Karoo Basin as well as with other basins across Gondwana. These discoveries also indicate that a population of herbivorous tapinocephalids survived as rare constituents of the tetrapod fauna after most generic richness within the clade had already been lost.

Along the >650 km long southern margin of the Karoo Basin in South Africa, we traversed four evenly spaced stratigraphic transects and collected 22 samples of volcanic, air-fall tuffs thought to be distal deposits derived from the Permian–Triassic Southern Gondwanan volcanic arc. We present 469 new U-Pb zircon ages determined by sensitive high-resolution ion microprobe reverse geometry (SHRIMP-RG) at the Stanford–USGS Microanalytical Center in order to constrain the maximum depositional ages for the southern Karoo Basin strata. Weighted means of these youngest coherent zircon populations were selected to maximize the number of analyses while minimizing the mean square weighted deviation (MSWD) to increase the robustness and decrease the influence of Pb-loss and inheritance in determining the maximum depositional age. Maximum depositional ages for the marine Ecca Group range from 250 to 274 Ma, whereas in the conformably overlying terrestrial Beaufort Group maximum depositional ages ranged from 257 to 452 ...

Changes in elemental chemistry have been used to define stratigraphic correlations between wellbores in petroleum basins. Few publications, however, relate defined chemical stratigraphy to physical correlations, and none have been found that do so in fluvial systems. Here, chemostratigraphy is applied to Permian fluvial sediments within the Beaufort Group of the Karoo Basin in South Africa, and a correlation between three logged sections is defined. This correlation is tested against physically determined chronostratigraphic correlations achieved using Heli-LIDAR data to provide a high-resolution correlation between two sections 7 km (4.4 mi) apart, and mapping of strata using Google Earth to produce a correlation between sections 25.5 km (15.8 mi) apart. The chemostratigraphic characterization that is defined using data from fine-grained lithologies resulted in the recognition of eight chemostratigraphic packages, with thicknesses between 50 and 250 m (164 and 820 ft) over a stratigraphic interval of approximately 900 m (2953 ft). Two distinctive changes in geochemical composition of the coarser lithologies (fluvial channel belts) were seen over this interval. In the two sections that are 7 km (4.4 mi) apart, higher resolution subdivision of chemostratigraphic packages was achieved to produce four correlative geochemical units (30–60 m [98–197 ft] in thickness) that provide a high-resolution correlation. The chemostratigraphic and chronostratigraphic correlations are in close agreement in both the 7-km- (4.4-mi) and the 25.5-km- (15.8 mi) spaced sections. The thickness of the study interval and spacing of sections is analogous to published chemostratigraphy studies on subsurface sequences; thereby, ground truthing the use of chemostratigraphy for correlation in subsurface fluvial systems that are, to some degree, analogous to the Beaufort Group sediments of this paper.

Up to 12% of the mud-prone, ephemeral distributive fluvial system stratigraphy in the Permo-Triassic lower Beaufort Group, South Africa, comprises tabular fine-grained sandstone to coarse-grained siltstone bodies, which are interpreted as proximal to distal crevasse splay deposits. Crevasse splay sandstones predominantly exhibit ripple to climbing ripple cross-lamination, with some structureless and planar laminated beds. A hierarchical architectural scheme is adopted, in which ~ 1 m thick crevasse splay elements extend for tens to several hundreds of meters laterally, and stack with other splay elements to form crevasse splay sets up to 4 m thick and several kilometers in width and length. Paleosols and nodular horizons developed during periods, or in areas, of reduced overbank flooding are used to subdivide the stratigraphy, separating crevasse splay sets. Deposits from crevasse splays differ from frontal splays as their proximal deposits are much thinner and narrower, with paleocurrents oblique to the main paleochannel. In order for crevasse splay sets to develop, the parent channel belt and the location where crevasse splays form must stay relatively fixed during a period of multiple flood events. Beaufort Group splays have similar geometries to those of contemporary perennial rivers but exhibit more lateral variability in facies, which is interpreted to be the result of more extreme fluctuations in discharge regime. Sharp-based crevasse splay packages are associated with channel avulsion, but most are characterized by a gradual coarsening upward, interpreted to represent progradation. The dominance of progradational splays beneath channel belt deposits may be more characteristic of progradational stratigraphy in a distributive fluvial system rather than dominated by avulsion processes in a trunk river system. This stratigraphic motif may therefore be an additional criterion for recognition of distributive fluvial systems in the ancient record.

Fluvially deposited rocks of the Abrahamskraal Formation of the lower Beaufort Group in the South African Karoo record sediment deposition during the Middle Permian, the earliest terrestrial environment of Gondwana. A rich diversity of fossil tetrapods from this Formation provides a unique opportunity for understanding Middle Permian biodiversity changes in Gondwanan terrestrial ecosystems, but this is dependent on the existence of a robust stratigraphic framework that has been hampered by lack of lateral continuity of lithological markers combined with structural complexities relating to formation of the Cape Fold Belt. Because the Abrahamskraal Formation covers a large geographic area of the main Karoo Basin previous stratigraphic studies have been undertaken over large areas. This study combines geology and palaeontology to refine the stratigraphy of the Abrahamskraal Formation in a part of the southwestern Karoo Basin and revealed mappable lithological units with lateral continuity throughout the study area. The measured stratigraphic section manifests a total thickness of 2565 m for the Formation (the thickest occurrence of the Abrahamskraal Formation in the Beaufort Group). For the first time stratigraphic ranges of biostratigraphically important Middle Permian index taxa which have restricted stratigraphic ranges have been determined and, apart from dicynodonts, include the parareptile Eunotosaurus and the biarmosuchid therapsid Hipposaurus . The Abrahamskraal Formation comprises a 1104 m thick basal Eodicynodon Assemblage Zone, overlain by a 1441 m thick Tapinocephalus Assemblage Zone whose upper limit is 20 m below the Poortjie Member of the Teekloof Formation.

Recent interest in the main Karoo Basin of South Africa has been sparked by the possibility of extensive shale gas resources. Historical reflection seismic, petroleum exploration wells and regional magnetic data are used to better understand the distribution and geometry of dolerite intrusions within the basin that could have impacted the shale reservoir. The lowest concentration of dolerites are found in a region stretching from the southwest to the southeastern part of the basin around the town of Graaff-Reinet. These intrusions are confined to the Beaufort Group, ~1000 m shallower than the shale reservoir. In the southeastern Karoo around Queenstown, 5 to 30 km wide saucer-shaped sills extend down to ~800 m, with dips of between 2° and 8°. Further south, dolerite sheets around Somerset-East extend for over 150 km at dips of between 3° and 13°, and are imaged down to ~5 km. These dips appear to increase closer to the Cape Fold Belt in the south, although there is no correlation between the southern edge of these dolerites (i.e., the dolerite line) and the dip of sediments due to folding. Magnetic data are useful shale gas exploration to detect shallower (