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Continental ecosystems of the middle Permian Period (273–259 million years ago) are poorly understood. In South Africa, the vertebrate fossil record is well documented for this time interval, but the plants and insects are virtually unknown, and are rare globally. This scarcity of data has hampered studies of the evolution and diversification of life, and has precluded detailed reconstructions and analyses of ecosystems of this critical period in Earth's history. Here we introduce a new locality in the southern Karoo Basin that is producing exceptionally well-preserved and abundant fossils of novel freshwater and terrestrial insects, arachnids, and plants. Within a robust regional geochronological, geological and biostratigraphic context, this Konservat- and Konzentrat-Lagerstätte offers a unique opportunity for the study and reconstruction of a southern Gondwanan deltaic ecosystem that thrived 266–268 million years ago, and will serve as a high-resolution ecological baseline towards a better understanding of Permian extinction events. A new middle Permian fossil locality featuring a large abundance of exceptionally preserved plants and insects is identified in the Karoo Basin of South Africa. [ABSTRACT FROM AUTHOR]

Catastrophic ecosystem disruption in the late Permian period resulted in the greatest loss of biodiversity in Earth's history, the Permian-Triassic mass extinction (PTME). 1 The dominant terrestrial vertebrates of the Permian (synapsids) suffered major losses at this time, leading to their replacement by reptiles in the Triassic. 2 The dominant late Permian predatory synapsids, gorgonopsians, were completely extirpated by the PTME. The largest African gorgonopsians, the Rubidgeinae, have traditionally been assumed to go extinct at the Permo-Triassic boundary (PTB). 3,4,5 However, this apparent persistence through the sustained extinction interval characterizing the continental PTME 6 is at odds with ecological theory indicating that top predators have high extinction risk. 7 Here, we report the youngest known large-bodied gorgonopsians, gigantic specimens from the PTB site of Nooitgedacht 68 in South Africa. These specimens are not rubidgeine, and instead are referable to Inostrancevia , a taxon previously thought to be a Russian endemic. 8 Based on comprehensive review of the South African gorgonopsian record, we show that rubidgeines were early victims of ecosystem disruption preceding the PTME and were replaced as top predators by Laurasian immigrant inostranceviines. The reign of this latter group was short-lived, however; by the PTB, gorgonopsians were extinct, and a different group (therocephalians) became the largest synapsid predators, before themselves going extinct. The extinction and replacement of top predators in rapid succession at the clade level underlines the extreme degree of ecosystem instability in the latest Permian and earliest Triassic, a phenomenon that was likely global in extent. • New saber-toothed Permian predator connects northern and southern hemisphere faunas • Local extinctions of Gondwanan carnivores facilitated influx of Laurasian taxa • Top predatory niches extremely unstable during Permian-Triassic extinction • Large predators are early victims of ecosystem destabilization in deep time Kammerer et al. present a new species of large, saber-toothed predatory synapsid from rocks of late Permian age in South Africa. Study of tetrapod stratigraphic ranges shows extreme instability in top predator niches around the Permian-Triassic mass extinction, with four shifts at higher clade levels within a span of roughly two million years. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The Middle Permian tetrapod fauna of the South African Beaufort Group is taxonomically diverse and includes representatives of all major therapsid groups, including the earliest records of Eutheriodontia. In the Middle Permian, eutheriodonts are represented mainly by large therocephalians, which made up a large proportion of the vertebrate predators in these faunas. Here we describe the skull and partial skeleton of a large therocephalian from the uppermost Tapinocephalus Assemblage Zone (AZ) of South Africa. A combination of features, including the short snout, presence of three to four upper postcanines and presence of teeth on the pterygoid processes, indicates that the new specimen belongs to the earliest-diverging therocephalian family, Lycosuchidae. The presence of a well-developed midline ridge on the ventral surface of the vomer indicates that the new specimen can be referred to Simorhinella baini, a species previously represented only by a tiny juvenile skull. The new specimen forms the basis for a taxonomic re-evaluation of the Lycosuchidae as well as of the geographic and stratigraphic range of the family. We recognize two valid species within the Lycosuchidae: the type species Lycosuchus vanderrieti represented by five specimens and Simorhinella baini represented by two specimens, with an additional 22 specimens currently identifiable as Lycosuchidae incertae sedis. Lycosuchid specimens range throughout the Tapinocephalus and Pristerognathus AZs; specimens of Simorhinella are restricted to the Tapinocephalus AZ, whereas Lycosuchus specimens are documented in both the Tapinocephalus and Pristerognathus AZs. [ABSTRACT FROM AUTHOR]

Abstract: Earth experienced its most devastating extinction event at the end of the Permian period 251million years ago (Ma). Despite an estimated 75 to 90% loss of species globally in both marine and terrestrial realms across the Permian–Triassic Boundary (PTB), around 20% of the terrestrial tetrapod genera in southwestern Gondwana survived and were immediately joined by a number of immigrant taxa to occupy most of the vacant niches of the earliest Triassic. Preserved in the Karoo Basin of South Africa is an almost continuous stratigraphic record of terrestrial sedimentation through the PTB that hosts a fossil record of ecosystem collapse, survivorship and recovery. The adaptation of the mammal like reptiles (therapsids) of the Lystrosaurus Assemblage Zone to a highly seasonal, potentially drought prone semi-arid earliest Triassic Karoo Basin is associated with changes in modes of fossilisation. Isolated dicynodont skulls and postcranial elements are commonly found in the latest Permian. However, in the earliest Triassic the dicynodonts occur as articulated, curled-up skeletons and multi-individual monotaxic bonebeds. Lack of epiphyses and relatively small skull length confirm that the bonebeds comprise several subadult Lystrosaurus declivis (L. declivis) carcasses. No significant evidence for hydraulic bone concentration along with clusters of ribs in life position points to complete carcasses being present at the site of death, and suggests that animals behaviourally congregated before perishing together. The bonebeds are hosted by an 8m thick horizon of floodplain mudrocks in the lower Katberg Formation named the Lystrosaurus abundant zone. The bonebed horizon is overlain by sand-filled mud cracks capped by coarse sediments indicative of rapid deposition during waning floods. Stable isotope analyses of pedogenic and early diagenetic calcite nodules in association with the bonebeds yield average δ13C values ranging from −9.5 to −5‰ and δ18O values of 13.5 to 16‰, respectively. These isotope values support a seasonally cold, semi-arid climate at high latitude (~55°S). The presence of vertebrate burrow casts on bonebed horizons and evidence of shelter sharing suggests that tetrapods were attempting to escape extreme climatic conditions. Aggregation behaviour of subadult Lystrosaurus during unusual cold snaps may best explain the origin of bonebed assemblages. [Copyright &y& Elsevier]

Robert Broom describedEosimops newtoniin 1921 based on a skull collected inTapinocephalusAssemblage Zone strata in South Africa, and the species has been largely overlooked since that time. Here we present several new specimens ofE. newtoni, including a nearly complete skeleton, that allow a much more thorough description of its morphology.Eosimops newtoniis diagnosed by two autapomorphies, a postorbital bar that is anteroposteriorly expanded in lateral view and a posterior median palatal ridge that forms a flattened, Y-shaped platform surrounding the anterior median palatal ridges. Other characters include a single median nasal boss; parietals widely exposed on the skull roof; presence of lateral anterior palatal ridges; anterior edge of caniniform process set off from the palatal rim forming a notch; a small number of ‘postcanine' teeth on the maxilla; a large, ventrally directed transverse flange on the anterior pterygoid ramus; a robust, tall, blocky crista oesophagea; a shovel-shaped jaw symphysis; dentary tables absent; posterior dentary sulcus present and bounded medially by a dorsally convex blade; at least one ‘postcanine' tooth present on the dentary blade; three sacral vertebrae; cleithrum present; dorsal margin of the coracoid foramen formed by the scapula; proximal and distal ends of the humerus offset by approximately 90°; ectepicondylar foramen present; and trochlea and capitellum distinct. Comparison withBrachyprosopus broomiandKoupia koupensisshows that neither species is likely to be a junior synonym ofE. newtoni. Phylogenetic analysis reconstructsE. newtonias the most basal member of Pylaecephalidae. We also reassess the homologies and distribution of the dentary table and posterior dentary sulcus in dicynodonts in light of the jaw morphology ofE. newtoni. The stratigraphic range ofEosimops newtonibegins in theTapinocephalusAssemblage Zone, 1565 metres above the Ecca–Beaufort contact, and extends into thePristerognathusAssemblage Zone. [ABSTRACT FROM AUTHOR]

During the Permian, tetrapods showed a major transition from basal synapsid-dominated faunas in the first half to therapsid-dominated faunas in the second. The transition was significant in marking the beginning of richer and more complex communities, a precursor to modern terrestrial ecosystems. This changeover may have been gradual or abrupt, but its study has been complicated by the postulated occurrence of a substantial hiatus in the fossil record, termed "Olson's Gap", which obscured the nature of the turnover. New evidence from redating of key tetrapod-bearing units of the American southwest and European Russia confirms that there is no gap in the fossil record of Permian tetrapods. Indeed, evidence for substantial sampling bias in the Permian tetrapod fossil record as a whole is queried. [ABSTRACT FROM AUTHOR]

At the Upper Permian site in a quarry at Wagondrift, near Estcourt (KwaZulu-Natal, South Africa), many Glossopteris leaves are found at various angles to the horizontal in unbedded, structureless sediments, suggesting slumping in a subaqueous levee setting. Other Glossopteris leaves are found associated with small ripples in very fine sandstone, suggesting overbank spill. The presence of a whorl of the fragile sphenopsid Sphenophyllum and the delicate wing of a plecopteran (Perlaria, Stone-fly) of which the nymph is fully aquatic, suggest proximity to a fresh-water environment, rather than deposition in turbidites. [ABSTRACT FROM AUTHOR]