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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.

Lanthanostegus is an unusual dicynodont known from only two partial skulls from a single locality near Jansenville in the Eastern Cape Province of South Africa. Although these specimens can be constrained to near the base of the late middle Permian (Guadalupian) Abrahamskraal Formation, their precise age is uncertain as a result of diachroneity of the base of the Formation and the absence, in the Jansenville area, of index taxa to correlate this horizon with the biostratigraphy established in the Western Cape Province. Here, we describe a third skull that we identify as Lanthanostegus, which we recently discovered from a locality north of Laingsburg, on the western side of the main Karoo Basin. This skull reveals morphological details of the palate, occiput, and lower jaw that are not preserved in the described specimens of Lanthanostegus mohoii and will advance understanding of this poorly known dicynodont. This discovery provides the first direct correlation between the lower Abrahamskraal Formation at Jansenville on the eastern side of the basin and the southwestern part of the basin, and suggests that Lanthanostegus occurs in the lowest Tapinocephalus Assemblage Zone (AZ), or possibly to a new assemblage transitional between the Eodicynodon and Tapinocephalus AZs. This supports earlier work proposing that the Eodicynodon AZ is present only on the western side of the Karoo Basin and that the transition from a marine to continental depositional environment occurred later toward the East.

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.

The main Karoo Basin (MKB), internationally renowned for its wealth of fossil tetrapods, has been lithostratigraphically subdivided into three discrete regions: two (east and west) proximal facies adjacent to the Cape Fold Belt, and a distal facies, away from the Cape Fold Belt. Because of lithological differences between formations of the proximal and distal sectors of the MKB, it has been difficult to correlate time-equivalent lithostratigraphic units in the different sectors. Palynology provides a tool for refining stratigraphic correlations within the MKB, but only species with restricted ranges are biostratigraphically significant. Restricted-range palynomorph taxa from the Ecca and Beaufort groups indicate the following relationships: the lowermost Vryheid Formation palynoflora can be strongly correlated with that of the Prince Albert Formation, whereas the Whitehill–Collingham formations and No. 2 seam (Vryheid Formation), and the Ripon Formation and No. 4 seam (Vryheid Formation) can be tentatively linked using palynology. The lower–middle Normandien Formation in the north is chronologically equivalent to the Ripplemead member of the Balfour Formation in the south. Although the Ecca–Beaufort Group boundary is known to be diachronous, restricted-range palynomorphs cannot yet confirm that the uppermost Ecca Group in the northern part of the basin was deposited at the same time as the lower Beaufort Group in the south. This study demonstrates that despite diachronous ranges of some taxa, palynology is useful in correlating age-equivalent lithostratigraphic units in the proximal and distal sectors of the basin. A new First Appearance Datum (FAD) palynozonation for the Karoo is presented that is calibrated by the most recent radiometric dates for South Africa, Australia, and South America. The new zones are also correlated with Permian successions in Antarctica, Zambia, Botswana, and India. Future palynostratigraphic work in South Africa must take into account the ranges and FADs of these palynomorph taxa in order to make meaningful biostratigraphic correlations in the Karoo Basin and across Gondwana.

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.

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.

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.

The basal strata of the Beaufort Group of the South African Karoo Basin, comprising the western Abrahamskraal and eastern Koonap formations, contain the most time extensive record of Middle Permian fossil tetrapods and hold the key to understanding Middle Permian biodiversity change in the continental realm. To determine faunal stratigraphic ranges a reliable lithostratigraphic framework for Middle Permian Beaufort deposits is essential. Until now this has proved difficult to achieve, largely due to the homogeneity of the fluvial succession coupled with structural complexity as a result of Cape Fold Belt orogenesis. Accordingly, the Abrahamskraal Formation has been only locally subdivided on the basis of sandstone packages but regional stratigraphic subdivision has not yet achieved satisfactorily. Collation of stratigraphic sections from around the Karoo Basin for this study demonstrates the presence of four sandstone packages are present within the Abrahamskraal Formation in the south-western corner of the basin. These sandstone packages are given member status, based upon the nomenclature of Le Roux (1985) with the addition of the newly recognised Grootfontein Member. The Combrinkskraal and Grootfontein Members occur in the lower half of the Abrahamskraal Formation and are laterally persistent along the southern margin of the basin. The Koornplaats Member is more restricted to the south west corner of the basin, where it quite thick, suggesting the narrowing of the highly channelized area. The overlying Moordenaars Member, more extensive towards the north than underlying packages, indicates subsequent northwesterly expansion of the locus of active channelization with time. Although thin sandstone packages in the more easterly positioned and stratigraphically equivalent Koonap Formation, this does not facilitate lithostratigraphic subdivision of this part of the stratigraphic succession and may indicate a different form of fluvial architecture. Our study provides a regional lithostratigraphic scheme for the Abrahamskraal Formation that will facilitate its biostratigraphic subdivision and the investigation of Middle Permian Gondwanan basin evolution.

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 (

Dicynodonts are the most abundant therapsids from the Beaufort Group (Karoo Basin, South Africa), and they have been used as index fossils to define most of the Beaufort biozones. Although speciose during the Late Permian, dicynodont diversity was greatly reduced by the end-Permian mass extinction. The Cynognathus Assemblage Zone, the uppermost biozone of the Beaufort Group, is traditionally known to host only the dicynodonts Kannemeyeria simocephalus and Kombuisia frerensis. Recent biostratigraphic research in this biozone has revealed the presence of two more poorly known dicynodont genera, Angonisaurus and Shansiodon, which are biostratigraphically constrained to the uppermost Cynognathus Assemblage Zone (subzone C). Although these taxa have been reported from subzone C of the Cynognathus Assemblage Zone previously, we provide the first detailed description of the material in question and justifications for the taxonomic identifications. The presence of Angonisaurus in the Cynognathus subzone ...

The first dicynodont reported for the Permian of South America is described in detail here. The specimen consists of a partial skull and associated lower jaws, collected from the Serra do Cadeado locality, Rio do Rasto Formation, Brazil. The specimen was assigned to the genus Endothiodon Owen in a preliminarily description published in the 1970s. This identification implied a direct correlation with some of the well-established biozones of the Beaufort Group, South Africa, where this taxon is known to occur. Although badly weathered, the Brazilian material preserves several features that allow us to confirm its assignment to Endothiodon, such as the pineal foramen situated on a boss, the bulbous swellings of the dentaries, a boss situated on the ventral margin of the jugal, the extensive number of dentary teeth and the upturned pointed beak of the lower jaw. However, this set of characters is not enough to establish a specific taxonomic assignment for the specimen, although it seems to be more closely related to E. bathystoma, E. uniseries and E. whaitsi than to E. mahalanobisi. The biostratigraphical correlations proposed for the tetrapod faunas of the Rio do Rasto Formation highlight the similarities between these associations and others from the Mid and Late Permian of South Africa and Eastern Europe. However, until now, these correlations are tentative because only a few faunal elements have been recovered from Brazil, and most of them lack stratigraphic data on the levels from where they were collected. Due to the presence of Endothiodon, at least part of the Rio do Rasto Formation can be correlated with deposits in India, Malawi, Mozambique, South Africa, Tanzania, Zambia and Zimbabwe.

Therapsid and other tetrapod fossils from the South African Karoo Supergroup provide the most detailed and best studied terrestrial vertebrate record of the Middle and Late Permian. The resulting biostratigraphic scheme has global applicability. Establishing a temporal framework for these faunas has proven difficult: magnetostratigraphy has been hampered by a Jurassic overprint, and intercorrelation with Permian marine sequences has been equivocal. Here we report U-Pb zircon isotope dilution–thermal ionization mass spectrometry (ID-TIMS) dates for five volcanic ashes interbedded with fossils from the Pristerognathus , Tropidostoma , and Cistecephalus vertebrate biozones of the Beaufort Group. This temporal framework allows correlation to marine zonations and improves understanding of rates of faunal evolution and patterns of basin evolution. Our results identify no correlative vertebrate extinctions in the Karoo Supergroup to the marine end-Guadalupian mass extinction and raise the question of whether there is any record of a terrestrial extinction related to the Emeishan large igneous province.

Ichnological and sedimentological analyses in the Eastern Cape allowed the first description of a Cochlichnus-dominated ichnofossil site from the mid- to Upper Permian Middleton Formation (Karoo Supergroup) in South Africa. The locality is within the uppermost Pristerognathus Assemblage Zone, a biostratigraphic interval characterized by a low vertebrate biodiversity at the turn of the mid- to Late Permian. Our field data indicates that the surficial bioturbation of very fine to fine-grained sand layers resulted from life activities of shallow infaunal and epifaunal invertebrates (possibly annelids, aquatic oligochaetes, nematodes, insect larvae) and fish. The morphology of the trails, their relationship to the substrate and the behaviour inferred from them indicate that the tracemakers developed a strategy that facilitated the optimization of low food resources in a permanently submerged freshwater setting. Combined ichnological and sedimentological evidence suggests a low-energy, freshwater lacustrine depositional environment, where occasional higher energy currents brought nutrients. Data also imply that colonization of these erratic event beds by opportunistic sediment-feeders was short-lived and followed by longer intervals of lower energy deposition under possibly poorly oxygenated conditions. We propose that these event beds as well as the sporadic red mudstones of the Middleton Formation may have formed during short-term, higher storm-frequency and dryer periods, signalling changes in the otherwise humid climate in this part of the main Karoo Basin during the mid- to Late Permian.

To date, all sites where gold has been recorded in KwaZulu-Natal have been in rocks of Archaean and Proterozoic Age. The site described is a heavy-mineral-rich sandstone bed of the Permian Vryheid Formation (Ecca Group) near Muden in the KwaZulu-Natal midlands. Sedimentary structures in the sandstone units of the Vryheid Formation indicate that these deltaic deposits were produced by rivers flowing from the northeast, with minor longshore drift towards the southeast. The deltaic deposits consist of three units: a basal unit (Unit A) of shale and mudstone, which coarsen upward into siltstones with lenses of fine-grained sandstone; a middle unit (Unit B) of ferruginous sandstone and immature greywacke (argillaceous sandstone) beds that coarsen upwards; and an upper unit (Unit C) of medium- to coarse-grained lithic sandstones with lenses of grit and sparse small pebbles of white vein quartz. The sand grains are physically and chemically very immature, suggesting the possibility that most of the sand grains were reworked from the then unlithified glaciogenic Dwyka Group sediments; the primary source of which was the Transvaal Supergroup and the granite - greenstone belts of the provenance area presently located in northern and eastern South Africa. The identification of gold-bearing grains in sandstones of the Vryheid Formation (Karoo Supergroup) from near Muden lends strong support to the concept that the gold-bearing horizons of similar Permian age in the Beaufort Group near Prince Albert, Western Cape Province were formed as natural placer deposits. The heavy-minerals take the form of both individual mineral grains and inclusions in quartz and feldspar with gold occurring only as inclusions. The majority of heavy-minerals occur as thin lenses and stringers in sandstone of the upper part of Unit B, where sorting was poor and flow rates were normally insufficient to winnow out the lighter minerals. Less abundant, but moderately well sorted, heavy-mineral lenses occur on the upper surface of Unit C in the troughs of megaripples, where deposition was rapid prior to subsequent preservation by an overlying organic-rich mud of Unit A.

A traverse through the Balfour Formation was chosen in the area around the towns of Fort Beaufort and Alice in the Eastern Cape Province. The main objectives of the study were to map the lithological variations within the Balfour Formation and to distinguish it from the underlying Middleton Formation and the overlying Katberg Formation. A combined desktop, field and laboratory approach was used in this study. Aerial photographs, satellite images and digital topographical maps formed the basis of the desktop work. After desktop mapping, a number of field traverses were measured through the study area. Sedimentary structures were observed, photomosaics were done, stratigraphic sections were measured and samples were collected for thin sectioning, heavy mineral separation and major, trace and REE analysis. Sedimentological development of the Balfour Formation has been outlined in relation to its provenance during the Late Permian. Lithological variation of the Balfour Formation is characterised by alternating sandstone-dominated and mudstone-dominated members. Arenaceous Oudeberg and Barberskrans Members are contain facies ranging from intraformational conglomerates (Gmm), massive sandstones (Sm & Ss), horizontally laminated sandstones (Sh), planar and trough cross-bedded sandstones (Sp, Sl & St), trough cross-laminated sandstones (Sr) and fine-grained sediments (Fm & Fl), whereas the mudstone dominated members are characterised by the facies Fm and Fl. Lithofacies together with bedforms observed in the Balfour Formation were used in architecturalelement analysis. Sandstone–rich members are dominated by channel fill elements such as LS, DA, SB, LA and CH, whereas the fine-grained component consists of mainly, FF iii element. The mudstone-dominated members contain FF, CS and LV elements, with LA, SB and CH in the subordinate sandstones. Petrography, geochemistry and palaeocurrent analysis indicated that the source of the Balfour Formation was to the south-east and the rocks had a transitional/dissected magmatic arc signature. This led to the postulation of the Karoo Basin to have developed in a retro-arc foreland basin where there was supralithospheric loading in the Cape Fold Belt due to a compressional regime initiated by the subduction of Palaeo-Pacific plate underneath the Gondwana plate. The tectonic loading was episodic with eight major paroxysms affecting the Karoo Supergroup. The Balfour Formation coincides with the fourth paroxysm, this paroxysm in turn consists of two third-order paroxysm that initiated the deposition of the Oudeberg and Barberskrans Members in low sinuosity streams. Each paroxysm was followed by a period of quiescence and these resulted in the deposition of the Daggaboersnek, Elandsberg and Palingkloof Members in meandering streams. Depositional environments were determined mainly from the sedimentary structures and 3D architecture of the rock types. Sandstone rich members were formed by seasonal and ephemeral high energy low sinuous streams whereas the fine-grained rich members were formed by…

Remnants of diamond-bearing fluvial gravels of Cretaceous age have been preserved on the Ghaap Plateau north-west of Reivilo at 1455 m above sea level. The alluvial deposit contains well preserved fossil woods representing at least four periods: Post-Permian (Upper Karoo), Early Cretaceous, Late Cretaceous and Tertiary. The Karoo specimen has been derived from Beaufort Group sediments, now eroded from the Ghaap Plateau. More significant are the presence of Early and Late Cretaceous woods, both periods believed to have been wetter in the interior of southern Africa. In addition to the diamonds, other kimberlite derived minerals such as ilmenite and garnet have also been recovered from these gravels. Detailed mineral chemical analyses of the ilmenites and those occurring in primary sources within a radius of 120 km of the Mahura Muthla area indicate that the most likely source are kimberlites occurring to the south-south-east, indicating that the palaeo-channel was flowing from the south-east to the north-west. This is supported by the presence of ironstone and red chert cobbles and pebbles derived from the Proterozoic Kanguru Member outcropping directly south of the channel. Further evidence comes from a palaeo-tributary on Laurika which joined the main Mahura Muthla trunk stream from the south-west; limited pebble imbrications; and a decrease in the sizes of wood, agate and ironstone cobbles and pebbles in a northerly direction associated with an increase of roundness of these clasts. At the start of the Cretaceous the area was covered by sandstones of the Beaufort Group with overlying flood basalts of the Drakensberg Group. First during the Early Cretaceous the Mahura Muthla channel was incising into an easterly retreating palaeo-escarpment of Karoo basalts. Group 2 kimberlites such as Finch, Darleston and Duivelskop, had already intruded these basalts around 120Ma. The north-westerly orientated drainage was directly linked to the drainage basin of the Kalahari River draining the northern part of the northern Cape and southern Botswana via the palaeo-Molopo and lower Orange River. This period of erosion would have released an abundance of agates from the basalts that are so abundantly present in the gravels and also diamonds from these Group 2 kimberlites. On comparing the mineral chemistry of the ilmenites the most likely source for these kimberlitic minerals is the area to the south east of Mahura Muthla. Kimberlites occurring in this area include the Duivelskop Group, X 154, Pienaarspoort, the Bellsbank Group, Bull Hill and Mayeng. At least some of these could have provided diamonds to the gravels. Later during Upper Cretaceous times the Karoo basalts had been removed and the drainage stripped the remaining sediments of the Beaufort Group before the sinuous channel became locked and preserved within the Transvaal dolomites. Subsequently the channel became calcretised during the development of the African Surface in the Early Tertiary. Mahura Muthla remained part of the Kalahari River basin which fed the Molopo River and the lower Orange drainage network and by the Early Tertiary the latter had captured the Vaal and the upper and middle Orange River drainage basin which had been part of the Karoo River drainage for most of the Cretaceous.

The distant evolutionary ancestry of mammals is documented by a rich therapsid fossil record. While sphenacodontid synapsids are considered the sister-group of therapsids, the place of origin of therapsids is an enigma, largely because of a long standing morphological and temporal gap (Olson's Gap) in their fossil record. We describe a new large predatory synapsid, Raranimus dashankouensis gen. et sp. nov., from the Middle Permian of Dashankou in China which has a unique combination of therapsid and sphenacodontid features. This specimen is of great significance as it is a basal therapsid which is the sister taxon to all other therapsids. The fact that it was found in association with Early Permian tetrapods (Anakamacops and Belebey) suggests that it is the oldest therapsid and provides the first evidence of therapsid-bearing rocks which cover Olson's Gap. It further supports that therapsids may have had a Laurasian rather than Gondwanan origin.

The Lower Triassic Katberg Formation (Beaufort Group, Karoo Supergroup) in South Africa is a fine-grained, arenaceous unit deposited under ephemeral bedload-dominated fluvial conditions and previously interpreted as representing a continuous stratigraphic record. Its genesis was linked directly to the end-Paleozoic extinction event and was considered to exhibit the results of a trend towards aridification. The present study documents the lowermost Katberg Formation exposed at Carlton Heights, Northern Cape Province, to test the aridification hypothesis. Four lithofacies vary in both vertical and lateral relationships, with feldspathic sandstone dominating the stratigraphy. Pisolith-size nodular conglomerate consists of pedogenically derived carbonate nodules originally precipitated within aridisols, none of which are either exposed or reported from the formation. Rather, the only evidence of extreme aridification is found within channel lag, barform, and overbank deposits marking landscape degradation. Landscape aggradation is characterized by two feldspathic sandstone geometries where (1) medium-bedded, planar bedded, or ripple-laminated sheet sandstone is interpreted as ephemeral sheetflood deposits, and (2) thick-bedded, cross-laminated multi-lateral, lenticular sandstone is interpreted as associated with deeper, sand-bed braided (anabranching) systems. Overbank fines consist of polyphase siltstone paleosols in which bioturbated inceptisols were overprinted by gleysols wherein large pedogenic carbonate nodules precipitated under a high regional water table. Evidence exists for periodic drying in these wet regimes, but no evidence exists for extreme aridity. Hence, the lowermost Katberg Formation superficially exhibits only an aggradational sedimentological record, but significant diastems exist as evidenced by the concentration of aridisol precipitates at the base of each degradational cycle. A model for the Early Triassic in this part of the Karoo Basin is presented wherein this record is interpreted as a function of climate oscillations rather than either episodic uplift in the Cape Fold Belt or any ecosystem response to the end-Permian extinction.

The little-known Emakwezini Formation (Adelaide Subgroup, Beaufort Group, Karoo Supergroup) crops out in a narrow strip just inland of the eastern coast of South Africa in northern KwaZulu-Natal. It is an actively mined coal-bearing succession characterised by fining-upward successions of coarse- to fine-grained sandstones together with mudstones containing a fossil assemblage of animal traces, insects, molluscs, arthropods, fish and plants. Previously, only Glossopteris leaves and Phyllotheca australis had been described from this formation, on the basis of a few very small, scattered and poorly provenanced collections. Recent regional-scale sedimentary facies analysis (based on field relationships, provenance studies, palaeocurrent and subsurface data) together with palaeobotanical studies of a newly discovered, well-preserved and diverse palaeoflora from the Emakwezini Formation, have permitted a more detailed interpretation of the depositional environment. The current investigation also reveals the first evidence of the plant fossils Dictyopteridium flabellatum , Rigbya arberioides , Lidgettonia spp., and Trizygia speciosa in the upper parts of the Emakwezini Formation, strongly supporting a Late Permian age based on correlation with floras from Upper Permian units in the main Karoo Basin. In the lower part of the unit, within the partings of actively mined coal seams, our preliminary investigations also show the presence of a new flora including both the glossopterid fructification Ottokaria sp. (only known from the Lower Permian in South Africa) and the sphenopsid Schizoneura gondwanensis (typical of the Upper Permian in South Africa). With sediments sourced from a north-easterly continental interior, the Emakwezini Formation was deposited rapidly in a fluviolacustrine setting under moist conditions capable of supporting an abundant and diverse biota. The permanently moist environment in which the Emakwezini Formation was deposited contrasts with that of the time-equivalent lower Beaufort Group units in the main Karoo Basin where environmental indicators suggest deltaic, lacustrine and meandering fluvial systems developed in a seasonally dry and more arid setting. Thus, within southern Africa, during the Middle to Late Permian, the environmental conditions, including climate, were varied leading to a mosaic of continental depositional settings.

Two new assemblages (farms Christina and Moorfield) of plant fossils belonging to the Glossopterid flora are described from the northeastern part of the Main Karoo basin, within the Late Permian Normandien Formation, Beaufort Group, Karoo Supergroup. The Normandien Formation comprises three sandstone members (lower Frankfort, Rooinek, upper Schoondraai) each overlain by an argillaceous interval. Two informal plant fossil assemblage zones are distinguished in the field: a “Christina assemblage zone” defined by Morphotype Pnc1, Morphotype Pnc2, Morphotype Pnc3 and Morphotype Pnc7, between the Frankfort and Rooinek sandstones; a younger “Moorfield assemblage zone” between the Rooinek and Schoondraai sandstones, defined by Morphotype Pnm1 , Morphotype Pnm2, Morphotype Pnm3, Rigbya arberioides and Sphenophyllum speciosum. These two proposed plant fossil assemblage zones enable subdivision of the Dicynodon therapod assemblage zone coincident with the Normandien Formation, and the two plant fossil zones have been successfully mapped out over a large area.

The oldest records of mammal-like therapsids in Laurasia are from the Ocher Complex of Russia and the Xid- agou Formation of China, whereas in Gondwana they are restricted to the Eodicynodon Assemblage Zone, Beaufort Group of the South African Karoo. This fauna, which is rela- tively depauperate when compared with younger assemblage zones from the Karoo, shows an amazing diversity of ther- apsids including: dinocephalians (already represented by the carnivorous anteosaurids and the herbivorous tapinocepha- lids), anomodonts (including dicynodonts), gorgonopsians, and therocephalians. The last group is represented by two specimens in this assemblage zone. This paper presents a full description of these therocephalians, which are assigned to the scylacosaurid species Glanosuchus macrops and Ictidosau- rus angusticeps. We also discuss diversity trends of theroceph- alians and explore some hypotheses implicated by the diverse oldest record of therapsids, represented by five of the six major lineages of the group.

Seismic data provide a unique opportunity to understand the subsurface structure of dolerite sills that have intruded the Karoo Basin at multiple levels. These sills have intruded close to the Whitehill Formation at several locations within the basin, and may impact shale gas exploration of this horizon. In the southeastern Karoo Basin, around Queenstown, seismic data reveal the presence of 5–30 km wide saucer-shaped sills with vertical thickness of up to ~270 m each, and dips of between 2° and 8° at shallow stratigraphic levels. Farther south, dolerite sheets near Somerset-East are imaged down to a depth of ~5 km and extend for over 150 km, with dips of between 3° and 13°. These dips increase closer to the adjacent Cape Fold Belt in the south. Around Lesotho, at the highest stratigraphic levels, intrusions are dominated by dykes and fluid vents that are evident on seismic data as regions of diffused reflectivity. The lowest concentration of dolerite is found in a region in the south-central part of the basin around the town of Graaff-Reinet. Here intrusions are confined to the Beaufort Group, ~ 1000 m above the shale reservoir. This change in dolerite distribution will influence the location of shale gas exploration.

The holotype of Sauropareion anoplus, a procolophonoid reptile from the Lystrosaurus Assemblage Zone of the Beaufort Group, lowermost Triassic of South Africa, is described in detail. New information includes the presence of fields of teeth on the vomer, the palatine, and the pterygoid, and the presence of a relatively long, tear-shaped interpterygoid vacuity. The parabasisphenoid features relatively broad posterolateral wings. A cleithrum is present. An entepicondylar foramen is present, but neither an ectepicondylar foramen nor a supinator process are present. We coded Sauropareion for the data matrices in two recent studies that had excluded this genus from consideration in phylogenetic analyses. Running of these slightly augmented matrices results in numerous optimal trees (8 and 15 optimal trees), i.e. the inclusion of Sauropareion greatly weakens the resolution of the tree topologies; in one case the inclusion of Sauropareion highlights the lack of anatomical information available for most ...

A mid-Permian (Guadalupian epoch) extinction event at approximately 260 Ma has been mooted for two decades. This is based primarily on invertebrate biostratigraphy of Guadalupian–Lopingian marine carbonate platforms in southern China, which are temporally constrained by correlation to the associated Emeishan Large Igneous Province (LIP). Despite attempts to identify a similar biodiversity crisis in the terrestrial realm, the low resolution of mid-Permian tetrapod biostratigraphy and a lack of robust geochronological constraints have until now hampered both the correlation and quantification of terrestrial extinctions. Here we present an extensive compilation of tetrapod-stratigraphic data analysed by the constrained optimization (CONOP) algorithm that reveals a significant extinction event among tetrapods within the lower Beaufort Group of the Karoo Basin, South Africa, in the latest Capitanian. Our fossil dataset reveals a 74–80% loss of generic richness between the upper Tapinocephalus Assemblage Zone (AZ) and the mid- Pristerognathus AZ that is temporally constrained by a U–Pb zircon date (CA-TIMS method) of 260.259 ± 0.081 Ma from a tuff near the top of the Tapinocephalus AZ. This strengthens the biochronology of the Permian Beaufort Group and supports the existence of a mid-Permian mass extinction event on land near the end of the Guadalupian. Our results permit a temporal association between the extinction of dinocephalian therapsids and the LIP volcanism at Emeishan, as well as the marine end-Guadalupian extinctions.

The resistivity structure of the Karoo Basin has been determined by an extensive programme of some 280 deep electrical soundings (maximum current electrode spacing = 40 km). The very conductive carbon and pyrite- rich Whitehill Formation acts as an electrical basement to deep soundings where it is well developed. Beyond its limit in the east, the electrical basement consists of granites and metamorphic rocks and is highly resistive. Notwithstanding an appreciable difference in resistivity between the sandstone and mudstone components, the sandstones are neither sufficiently massive nor continuous to be detected separately in sounding curves. Exceptions are a few, thick, massive arenaceous turbidite fans occurring under an appreciable cover in the downwarped Karoo Trough, straddling the Lower Beaufort and Upper Ecca Subgroups at the southern extremity of the basin. The average resistivity of the sedimentary pile above the Whitehill Formation increases from north to south by more than an order of magnitude substantiating geological evidence of a sympathetic increase in diagenesis and metamorphosis. The Karoo Supergroup comprises one of the rare instances of a sedimentary basin where dolerite intrusions occur interbedded with sediments. The very high resistivity contrast between the resistive dolerite and the conductive sediment, results in an exceptionally high degree of electrical anisotropy. This feature has provided a unique opportunity to study the configuration of the network of dolerite intrusions in the sedimentary succession but simultaneously has often seriously restricted the depth of investigation. Previous geological investigations have demonstrated a tri-zonal vertical variation in intrusive style. The resistivity study has shown that elements in each of these zones have their own specific geophysical signature. The largest portion of the basal zone 3 with its flat lying dolerite sills of great lateral extent is confined to well-laminated, homogeneous shales with a high degree of anisotropy in the Lower Ecca Subgroup and is characterized by a low transverse resistance on sounding curves corresponding to a concomitant low content of dolerite. The onset of zone 2, which coincides with the appearance of the first sandstones in the Waterford Formation, is accompanied by a dramatic increase in transverse resistance and hence the amount of dolerite. This dolerite-rich zone, which continues through the Beaufort Group and partially into the higher Formations is characterised by a multitude of basin structures. The variation in structure of the network of dolerites correlates with that of the nexus of lenticular sandstones intercalated with shales and mudstones. Detailed investigations, such as the one in the De Aar area, show that the average percentage of dolerite in the dolerite bearing layer of zone 2 is 45% with a high of 85% and a low of about 10%. Regionally, zone 2 thins to the south but thickens to the east by a factor of at least 5, at the expense of zone 3. The thickening is associated with a lateral increase in the amount of dolerite. Towards the upper portion of zone 2 there is a lower concentration of intrusions and a trend towards smaller basin structures in the Molteno, Elliot and Clarens Formations. Arguably, the most important contribution of the resistivity soundings is the conclusive finding that in the uppermost zone 1, which extends from the surface to a depth of about 700 m, the dominant style of intrusion is that of steeply dipping sheets and vertical dykes and that the zone is especially dolerite-poor with the amount of dolerite only making up about 0.5% or less of the sediments. The nature of zone 1 is independent of the lithology and is due to the decrease of overburden pressure.