Dicynodon Assemblage Zone Research Articles

Did gorgonopsians survive the end-Permian “Great Dying”? A re-appraisal of three gorgonopsian specimens (Therapsida, Theriodontia) reported from the Triassic Lystrosaurus declivis Assemblage Zone, Karoo Basin, South Africa

Gorgonopsians were the dominant carnivores of the late Permian (Lopingian) and it is widely accepted that the clade became extinct at the Permian-Triassic boundary, almost 252 million years ago. However, South African collections house three historically-collected gorgonopsian specimens listed as Early Triassic in age, based on their discovery at localities producing the index fossil Lystrosaurus. Initial reports suggested that these specimens had been reworked from underlying Permian strata, but this possibility was never thoroughly addressed. The possible survival of gorgonopsians into the Triassic would significantly alter our understanding of the end-Permian mass extinction and post-extinction ecosystem dynamics. Here we use Synchrotron X-ray micro-computed microtomography to confirm the identifications and investigate the taphonomic histories of these three specimens. We also relocated the original localities to determine their stratigraphic position. We confirm that all three specimens are indeed gorgonopsians, belonging to the small-bodied genus Cyonosaurus, and that taphonomic assessments do not support reworking. Two of them can be confidently assigned to the latest Permian Lystrosaurus maccaigi-Moschorhinus Subzone of the Daptocephalus Assemblage Zone. In contrast, at the locality listed for the third specimen, NMQR 389, the lowermost outcropping strata belong to the upper Palingkloof Member of the Balfour Formation, which is Early Triassic in age. Despite the evident absence of Permian-aged rocks, other Permian fossils were reported from the same locality, thus casting doubts about the age of NMQR 389. Additionally, differences in preservation style between this skull and the newly collected material at the site cast doubt on its provenance. Although not supporting gorgonopsian survival into the Triassic, these new occurrences expand the range of the genus Cyonosaurus higher up in the extinction zone, increasing the complexity of the ecological turmoil that carnivores endured during “The Great Dying”.

Earliest evidence of Inostrancevia in the southern hemisphere: new data from the Usili Formation of Tanzania

ABSTRACT Gorgonopsia is an iconic group of saber-toothed, carnivorous therapsids. They have a rich fossil record in the Karoo Basin of South Africa, but are also relatively common components of coeval Malawian, Tanzanian, Zambian, and Russian assemblages. Phylogenetic analyses have demonstrated that African gorgonopsians form a monophyletic subclade distinct from their Russian relatives, which all fall out near the root of the cladogram, thus suggesting a northern hemisphere origin for the clade as a whole. Surprisingly, recent research has demonstrated that a species of Inostrancevia, a genus previously recorded solely in Russia, occurs in the upper Daptocephalus Assemblage Zone of the Karoo Basin, perhaps the result of immigration following the demise of endemic rubidgeine gorgonopsians in the lower subzone of that unit. Here we describe a large, isolated gorgonopsian premaxilla from a bone-rich, conglomeratic interval at the base of the Usili Formation of Tanzania’s Ruhuhu Basin. Based on its stratigraphic position and fossil content, this unit likely correlates with the Cistecephalus Assemblage Zone. The premaxilla can be confidently referred to the genus Inostrancevia on the basis of its four incisors, a feature unique to Inostrancevia among gorgonopsians. In contrast to the disjunct distribution of inostranceviines and rubidgeines in the uppermost Permian of South Africa, the Tanzanian Inostrancevia likely overlapped with large-bodied rubidgeines such as Dinogorgon and Rubidgea.

The tetrapod fauna of the upper Permian Naobaogou Formation of China: 6. Turfanodon jiufengensis sp. nov. (Dicynodontia).

The dicynodont fossils from the Naobaogou Formation of Nei Mongol, China are abundant and diverse but poorly studied. In this article, one nearly complete skeleton and four cranial specimens from the Naobaogou Formation are referred to the dicynodontoid genus Turfanodon as a new species, T. jiufengensis. Previously, Turfanodon was known only from upper Permian sites in Xinjiang and Gansu. The new specimens are referred to Turfanodon based on the following characters: snout tall with steeply sloping profile, anterior tip of the snout squared off, facial region heavily pitted, nasal bosses present as paired swellings near the posterodorsal margin of the external nares, preparietal depressed, intertemporal bar long and narrow, premaxilla contacting frontal, palatal surface of premaxilla exposed in lateral view, and anterior pterygoid keel restricted to the anterior tip of the anterior ramus of the pterygoid. Turfanodon jiufengensis is differentiated from the type species, T. bogdaensis, by a contact of the lacrimal with the septomaxilla, discrete, raised nasal bosses, the dorsal edge of the erupted portion of the canine tusk slightly posterior to the anterior orbital margin, an anterior extension of the lacrimal distinctly shorter than that of the prefrontal, and a premaxillary dorsal surface with a median ridge. The holotype skeleton of T. jiufengensis includes a complete axial column with 50 vertebrae (six cervical, 23 dorsal, six sacral, and 15 caudal). Turfanodon represents the first confirmed tetrapod genus shared by the late Permian faunas of the Junggar and Ordos basins, and appears to be the first dicynodont genus distributed across both tropical and temperate zones (based on paleoclimate reconstructions). Based on tetrapod fossil content, the Naobaogou Formation can be roughly correlated to the Daptocephalus Assemblage Zone of South Africa (255–252 Ma in age).

Calcic Vertisols in the upper Daptocephalus Assemblage Zone, Balfour Formation, Karoo Basin, South Africa: Implications for Late Permian Climate

ABSTRACT The fully continental succession of the Beaufort Group, Karoo Basin, South Africa, has been used in the development of environmental models proposed for the interval that spans the contact between the Daptocephalus to Lystrosaurus Assemblage Zones, associated by some workers with the end-Permian extinction event. An aridification trend is widely accepted, yet geochemical data indicate that the majority of in situ paleosols encountered in this interval developed in waterlogged environments. To date, the presence of calcic paleosols in the latest Permian can be inferred only from the presence of calcite-cemented pedogenic nodules concentrated in fluvial channel-lag deposits. Here, we report on the first empirical evidence of in situ calcic Vertisols found in the upper Daptocephalus Assemblage Zone near Old Wapadsberg Pass, one of eight classic localities in which the vertebrate turnover is reported in the Karoo Basin. Seven discrete intervals of calcic Vertisols, exposed over a very limited lateral extent, occur in an ∼ 25 m stratigraphic interval. Estimates of mean annual temperature and mean annual precipitation are calculated from geochemical measurements of one paleosol, and these estimates indicate that the prevailing climate at the time of pedogenesis was seasonally cold and humid. Correlation with adjacent stratigraphic sections indicates that the late Permian landscape experienced poorly drained and better-drained phases, interpreted to reflect a climate that varied between episodically dry and episodically wet. In contrast to a paleoenvironmental reconstruction of unidirectional aridification from strata in the Wapadsberg Pass region, this study provides new evidence for a wetting trend towards the Daptocephalus–Lystrosaurus Assemblage-Zone boundary.

Biostratigraphy of theDaptocephalusAssemblage Zone (Beaufort Group, Karoo Supergroup), South Africa

AbstractThe 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.

A new large cynodont from the Late Permian (Lopingian) of the South African Karoo Basin and its phylogenetic significance

AbstractThe Karoo Basin of South Africa has the best global record of Lopingian (Late Permian) non-mammaliaform cynodonts, currently represented by five species. We describe Vetusodon elikhulu gen. et sp. nov., documented by four specimens from the Daptocephalus Assemblage Zone. With a basal skull length of ~18 cm, it is the largest Lopingian cynodont and is also larger than Induan representatives of the group. Vetusodon elikhulu has a cranial morphology that departs notably from that previously documented for Permo-Triassic cynodonts. It features a short and extremely wide snout, resembling that of the contemporaneous therocephalian Moschorhinus, and has large incisors and canines that contrast with the small unicusped postcanines, suggesting a more important role of the anterior dentition for feeding. The dentary is extremely long and robust, with the posterior margin located closer to the craniomandibular joint than in other Lopingian and Induan cynodonts (e.g. Thrinaxodon). The secondary palate morphology of V. elikhulu is unique, being short and incomplete and with the posterior portion of the maxilla partly covering the vomer. A phylogenetic analysis suggests that V. elikhulu is the sister taxon of Eucynodontia and thus the most derived of the Lopingian to Induan cynodonts yet discovered.

Changing palaeoenvironments and tetrapod populations in the Daptocephalus Assemblage Zone (Karoo Basin, South Africa) indicate early onset of the Permo-Triassic mass extinction

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.

PALEONTOLOGY OF THE BLAAUWATER 67 AND 65 FARMS, SOUTH AFRICA: TESTING THE DAPTOCEPHALUS/LYSTROSAURUS BIOZONE BOUNDARY IN A STRATIGRAPHIC FRAMEWORK

Abstract: Vertebrate paleontologists have proposed a model for the terrestrial end-Permian event in the Karoo Basin, South Africa. The scenario envisions vegetational collapse that resulted in a phased extinction of vertebrate taxa in the uppermost Daptocephalus Assemblage Zone and overlying Lystrosaurus Assemblage Zone. These biodiversity patterns are placed into composite stratigraphic sections at key localities, several of which are in close spatial proximity. We present a stratigraphic framework at two of these localities, Old Lootsberg Pass and Tweefontein, physically correlated over ∼ 2 km distance into which new and previously reported fossils are placed. Glossopterid-dominated megafloras occur in both the Daptocephalus and Lystrosaurus biozones, along with palynological assemblages. Katbergia, a burrow used by others as an indicator of the transition and post-transition interval, occurs in paleosols much lower in the upper Daptocephalus Assemblage Zone, along with various subhorizontal cylindrical...

Redescription of the geikiid Pelanomodon (Therapsida, Dicynodontia), with a reconsideration of ‘Propelanomodon’

ABSTRACTCryptodont dicynodonts are some of the most abundant therapsid taxa in the upper Permian fossil record. Despite extensive taxonomic study of these families, the species diversity of geikiid cryptodonts remains problematic, particularly for the set of edentulous taxa in the genera Pelanomodon, Propelanomodon, and Geikia. Here, all known specimens of tuskless geikiid dicynodonts from the upper Permian Karoo Basin of South Africa are reevaluated. The genus Pelanomodon is redescribed based on a series of skulls representing a range of sizes. All tuskless geikiids from the Karoo Basin are considered to represent a single species (Pelanomodon moschops) that exhibited cranial dimorphism as adults. The nominal species Pe. moschops and Pe. rubidgei differ only in degree of facial boss development and are most parsimoniously interpreted as sexual dimorphs. Propelanomodon is considered to represent the juvenile morphotype of Pelanomodon moschops, as indicated by the geographic and stratigraphic overlap of the two taxa, the lack of any small skulls of the Pelanomodon morphotype in well-sampled localities, and the presence of specimens of intermediate size and morphology. ‘Propelanomodon’ specimens are distinctive among juvenile dicynodonts in having a significantly narrower intertemporal region than adults. Analysis of intertemporal width relative to total skull size in Pelanomodon and the abundant cryptodont taxa Aulacephalodon, Oudenodon, and Tropidostoma suggests that Pelanomodon had a unique growth trajectory. Based on available stratigraphic data, Pelanomodon was restricted to the uppermost Permian Daptocephalus Assemblage Zone of the South African Beaufort Group and was a victim of the end-Permian mass extinction.SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVPCitation for this article: Kammerer, C. F., K. D. Angielczyk, and Jörg Fröbisch. 2015. Redescription of the geikiid Pelanomodon (Therapsida, Dicynodontia), with a reconsideration of ‘Propelanomodon’. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2015.1030408.

Lende chiweta, a new therapsid from Malawi, and its influence on burnetiamorph phylogeny and biogeography

ABSTRACTThe Chiweta Beds of Malawi have yielded a diverse late Permian fossil tetrapod fauna that correlates with that of the Cistecephalus Assemblage Zone of the South African Karoo Supergroup. Amongst the fossil therapsids from the Chiweta Beds is the well-preserved skull and lower jaw of a burnetiamorph, a group of biarmosuchians with numerous bosses and swellings on the skull. This specimen was reported in a preliminary paper in 2005 as the first burnetiamorph described outside of South Africa and Russia. Reanalysis of the morphology and phylogeny of this specimen places Lende chiweta, gen. et sp. nov., as the sister taxon to the clade formed by Proburnetia (Paraburnetia (Pachydectes, Bullacephalus, Burnetia, Niuksenitia)). The greatest diversity of this basal therapsid group is from South Africa, with six of nine described genera and a stratigraphic range that extends from the middle Permian Tapinocephalus Assemblage Zone to the upper Permian Dicynodon Assemblage Zone. Bearing in mind the constraints that govern fossil preservation, current data suggest that what is now southern Africa may have been the area of origin for burnetiamorphs. Under this premise, what is now central Africa represented a corridor that allowed migration of representatives of the group between the southern and northern portions of Pangea during the late Permian.http://zoobank.org/urn:lsid:zoobank.org:pub:BB094736-24AE-4B98-A33CBD7B7668DC2FSUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVPCitation for this article: Kruger, A., B. S. Rubidge, F. Abdala, E. Gomani Chindebvu, and L. L. Jacobs. 2015. Lende chiweta, a new therapsid from Malawi, and its influence on burnetiamorph phylogeny and biogeography. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2015.1008698.

The Daptocephalus Assemblage Zone (Lopingian), South Africa: A proposed biostratigraphy based on a new compilation of stratigraphic ranges

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.

Is the vertebrate-defined Permian-Triassic boundary in the Karoo Basin, South Africa, the terrestrial expression of the end-Permian marine event?

The end-Permian extinction records the greatest ecological catastrophe in Earth history. The vertebrate fossil record in the Karoo Basin, South Africa, has been used for more than a century as the standard for understanding turnover in terrestrial ecosystems, recently claimed to be in synchrony with the marine crisis. Workers assumed that systematic turnover at the Dicynodon assemblage zone boundary, followed by the appearance of new taxa directly above the base of the Lystrosaurus assemblage zone, is the continental expression of the end-Permian event and recovery. To test this hypothesis, we present the first highprecision age on strata close to the inferred Permian-Triassic boundary. A U-Pb isotope dilution–thermal ionization mass spectrometry zircon age of 253.48 ± 0.15 Ma (early Changhsingian) is from a silicified ash layer ~60 m below the current vertebrate-defined boundary at Old Lootsberg Pass (southern South Africa). This section yields newly discovered plants and vertebrates, and is dominated by a normal polarity signature. Our collective data suggest that the Dicynodon-Lystrosaurus assemblage zone boundary is stratigraphically higher than currently reported, and older than the marine extinction event. Therefore, the turnover in vertebrate taxa at this biozone boundary probably does not represent the biological expression of the terrestrial end-Permian mass extinction. The actual Permian-Triassic boundary in the Karoo Basin is either higher in the Katberg Formation or is not preserved. The currently accepted model of the terrestrial ecosystem response to the crisis, both in this basin and its extension globally, requires reevaluation.

A comprehensive taxonomic revision of Dicynodon (Therapsida, Anomodontia) and its implications for dicynodont phylogeny, biogeography, and biostratigraphy

ABSTRACT The dicynodont wastebasket genus Dicynodon is revised following a comprehensive review of nominal species. Most nominal species of Dicynodon pertain to other well-known dicynodont genera, especially Oudenodon and Diictodon. Of the Karoo Permian species that are referable to “Dicynodon” sensu lato, we recognize four common, valid morphospecies: Dicynodon lacerticeps, D. leoniceps, D. woodwardi, and Dinanomodon gilli, comb. nov. Eleven additional species of “Dicynodon” are recognized worldwide: D. alticeps, D. amalitzkii, D. bathyrhynchus, D. benjamini, D. bogdaensis, D. huenei, D. limbus, D. sinkianensis, D. traquairi, D. trautscholdi, and D. vanhoepeni. Morphometric analysis of D. lacerticeps and D. leoniceps specimens recovers statistically significant separation between these species in snout profile and squamosal shape, supporting their distinction. A new phylogenetic analysis of Anomodontia reveals that “Dicynodon” is polyphyletic, necessitating taxonomic revision at the generic level. D. benjamini and D. limbus are basal cryptodonts, whereas the other valid “Dicynodon” species are basal dicynodontoids. The genus Dicynodon is restricted to D. lacerticeps and D. huenei. We reinstate use of Daptocephalus, Sintocephalus, Turfanodon, Daqingshanodon, Jimusaria, and Gordonia for other species. We synonymize Vivaxosaurus permirus and Dicynodon trautscholdi (as V. trautscholdi, comb. nov.) We establish new generic names for several species formerly included in Dicynodon: Peramodon amalitzkii, comb. nov., Keyseria benjamini, comb. nov., Euptychognathus bathyrhynchus, comb. nov., Syops vanhoepeni, comb. nov., and Basilodon woodwardi, comb. nov. Of the main Karoo Permian taxa, Dicynodon, Basilodon, and Dinanomodon range throughout the Cistecephalus and Dicynodon assemblage zones, but Daptocephalus is restricted to the Dicynodon Assemblage Zone. An online version of this Memoir containing color versions of Figures 4 to 152 is available online on the publishers' website. Subscribers accessing the Memoir online may also download a high-resolution version of the pages, but due to its size please note that it is available in 4 parts in the “supplemental files” area. Supplemental data matrices and specimen lists are also available in the “supplemental files” area.

Tetrapod fauna of the lowermost Usili Formation (Songea Group, Ruhuhu Basin) of southern Tanzania, with a new burnetiid record

ABSTRACT Vertebrate fossils from the Ruhuhu Basin of southern Tanzania have been known for over 75 years, but the details of their stratigraphic distribution remain imperfectly understood. Recent fieldwork in the Upper Permian Usili Formation (Songea Group) has led to the discovery of a tetrapod assemblage in a conglomeratic unit at its base. The fossils are concentrated in matrix-supported intraformational clay pebble conglomerates interpreted as mass flow deposits in wide, shallow channels in the distal reaches of an alluvial fan. Included in this new collection are fossils representing the first record of a burnetiid therapsid from Tanzania. The anatomy of the interorbital and intertemporal skull roof indicates that the Usili burnetiid most closely resembles Burnetia from the Dicynodon Assemblage Zone of South Africa's Beaufort Group. Review of the Usili Formation tetrapod fauna recognizes 29 genera, 6 of which are endemic (Katumbia, Kawingasaurus, Pachytegos, Peltobatrachus, Ruhuhucerberus, Titanogorgon, as well as a new, undescribed cryptodontian dicynodont). In addition, eight genera are shared between the basal conglomerate and rocks higher in section, which suggests that the available data fail to support the recognition of two faunal horizons within the Usili Formation, as was suggested previously. The recognition of a single (undivided) Usili tetrapod fauna calls for several therapsid genera to have unequal stratigraphic ranges (and temporal durations) in the Ruhuhu and Karoo basins. We suggest that the fine-scale biostratigraphic utility of therapsids likely diminishes between basins, especially when rates of subsidence, depositional setting, and paleoenvironment are taken into consideration.

An autochthonous glossopterid flora with latest Permian palynomorphs and its depositional setting in the Dicynodon Assemblage Zone of the southern Karoo Basin, South Africa

The discovery of a plant-fossil assemblage, situated ∼ 70 m below the vertebrate-defined Permian–Triassic boundary, allows for the characterization of part of the Late Permian landscape in the southern Karoo Basin. The megafloral and microfloral assemblages are preserved in association with an O-horizon above a weakly developed palaeosol, exposed in both New and Old Wapadsberg Pass, Eastern Cape Province, South Africa. Stable-isotope geochemical evidence indicates that pedogenesis occurred under conditions of a high regional water table, and the palaeosol was entombed by overbank or avulsion deposits in an aggradational landscape that includes tuffite. The low-diversity macroflora contains gymnospermous ( Glossopteris) and sphenopsid ( Phyllotheca, Trizygia) elements that include vegetative (axial, leaf) and reproductive (strobilar) remains. Glossopteris leaves are microphyllous and may reflect the taxon's physiological response to purported climate perturbation or wetland edaphic conditions, and exhibit a range of plant–animal interactions. Palynological residues contain sphenophyllalean cuticles, and the microfloral assemblage is consistent with a low-diversity glossoperid-dominated woodland with a sphenopsid understory. Extrabasinal elements include representatives of peltasperms ( Alisporites), corystosperms ( Falcisporites), and conifers ( Lueckisporites). Pollen conforming to Lunatisporites pellucidus is present in the assemblage and is considered an indicator taxon for the latest Permian to Early Triassic. When compared to palynological assemblage zones in Australia, the Wapadsberg Pass flora is assigned a Late Changhsingian age and, therefore, represents the youngest autochthonous, Glossopteris-dominated flora to be reported from Gondwana. These results extend a palynostratigraphic framework across the Southern Hemisphere that complements other zonations presently applied to the Karoo Basin succession.

Portrait of a Gondwanan ecosystem: A new late Permian fossil locality from KwaZulu-Natal, South Africa

The Clouston Farm locality, assigned to the Lopingian Epoch and occurring within the Normandien Formation of the northeastern Karoo Basin, provides evidence for a community of diverse vascular plants occupying riparian woodland. The depositional environment is interpreted as an abandoned trunk channel that preserved a megaflora in slack-water phases punctuated by overbank deposits from rare flood events. Of 9772 plant specimens tabulated from an unbiased census of all fragments greater than ~ 1 cm 2, there are 51 distinct organ morphotypes, including glossopterids, sphenopsids, and ferns, collectively represented as foliage, axes, fructifications, and dispersed seeds. Of the 11 most abundant morphotypes 10 are glossopterid morphotypes or variant subtypes, in addition to a sphenopsid. Glossopterid morphotype dominance also is reflected in the palynoflora. Palynological data indicate a Wuchiapingian age for the locality. A specimen of the dicynodont ‘ Oudenodon,’ found in a nearby stratigraphically equivalent outcrop, is attributable to the Dicynodon Assemblage Zone, assigned a younger Changhsingian age. A rich record of plant–insect associations demonstrates an elevated frequency of external foliage feeding by mandibulate insects and lower incidence of oviposition by palaeodictyopteroid and odonatopteroid taxa. Evidence for piercing-and-sucking and galling is rare. The most abundant plant taxon (glossopterid Morphotype C2a) is the most intensively herbivorized, overwhelmingly by external feeding and ovipositing insects. Insect damage on this host is beyond that predicted by floristic abundance alone. This specificity, and high herbivory levels on other glossopterid taxa, demonstrates extension of the Euramerican pattern toward the preferential targeting of pteridosperms. The Clouston Farm site provides a glimpse into a late Permian ecosystem of primary producers, herbivores, and insectivores—a prelude to the crisis that engulfed life at the end of the period.

Analysis of millerettid parareptile relationships in the light of new material of Broomia perplexa Watson, 1914, from the Permian of South Africa

Synopsis A second specimen of the poorly known millerettid Broomia perplexa is reported. It consists of a cranium and partially articulated postcranium. As indicated by its small size (ca. 35% shorter skull than the holotype) and unfused pelvis and limbs, the new specimen is a sub‐adult individual. Comparison with the holotype reveals only minor differences that are ascribed to ontogenetic or individual variation. Accordingly we consider the new specimen to represent the second record of Broomia, discovered 90 years after the description of the holotype. A preliminary phylogenetic analysis of millerettid inter‐relationships identifies Broomia as a millerettid related to the genus Millerosaurus. The enigmatic parareptile Eunotosaurus africanus is nested within Millerettidae as the sister taxon of Milleretta rubidgei. Whereas millerettids are well known from the latest Permian Dicynodon Assemblage Zone of the Beaufort Group of South Africa, Broomia and Eunotosaurus are found in the Middle Permian Tapinocephalus Assemblage Zone. The new Broomia specimen not only complements our knowledge of this early millerettid but also shows, in addition to recent findings in the same area, that the lowermost Beaufort Group is at least 1200 m thick in this area compared with ca. 2500 m in the western part of the Karoo Basin.

A new burnetiamorph (Therapsida: Biarmosuchia) from the Lower Beaufort Group of South Africa

The basal clade Burnetiamorpha is known from only two specimens representing two genera, Proburnetia from the Severodvinskian horizon of the Vyatka River Basin in the Kotelnich district of Russia, and Burnetia from the Dicynodon Assemblage Zone of the Beaufort Group of South Africa. Both genera are of Late Tatarian (Late Permian) age. This paper describes the cranial morphology of a new genus of burnetiamorph, Bullacephalus, from the Late Permian Tapinocephalus Assemblage Zone of the Beaufort Group of South Africa. It is known from a relatively complete skull and lower jaw and is the best preserved burnetiamorph yet discovered. Apart from being the oldest member of the clade, Bullacephalus is also morphologically the least derived and provides new evidence on the phylogeny of this poorly understood group of basal therapsids.

A New Basal Lystrosaurid Dicynodont from the Upper Permian of South Africa

A new genus and species of late Permian dicynodont, Kwazulusaurus shakai, is described on the basis of a complete skull from the late Permian Dicynodon Assemblage Zone of the South African Beaufort Group. It is an advanced form which shows characters, such as the shape of the snout and the loss of the ectopterygoid, that link it to the early Triassic genus Lystrosaurus. Kwazulusaurus represents the most basal member of the lystrosaurian lineage. The phylogeny of progressive pristerodontian dicynodonts is discussed. It appears possible that the Kannemeyeriiformes and Lystrosauridae do not form a monophylum, as previously assumed. Instead a sister‐group relationship between lystrosaurids and dicynodontids plus kannemeyeriiforms is suggested.

Palaeomagnetism and palaeozoic palaeogeography of Gondwana and European terranes

Over the past decade researchers working on the rocks of the Beaufort Group in the main Karoo Basin of South Africa have vastly increased our understanding of this important Permo-Triassic sequence. Many new fossil forms have been discovered, allowing for breakthroughs into the biodiversity, biogeography and biostratigraphy of the group. Taxonomic and phylogenetic advances are many and varied, and cover most of the vertebrate taxa, but with emphasis placed on the temnospondyl amphibians, archosauriforms and non-mammalian synapsids, in particular the anomodontia. Biostratigraphic breakthroughs have centered on the Middle Permian Eodicynodon and Tapinocephalus assemblage zones, the Late Permian Dicynodon Assemblage Zone, and the Triassic Lystrosaurus and Cynognathus assemblage zones. Correlation of these biozones with better dated sequences in Europe, Russia and China has allowed for many chronostratigraphic refinements, which are in turn vital for sequence stratigraphical analysis of the basin fill. Based on fossil data, both the lower (Ecca–Beaufort) and upper (Beaufort–Molteno) contacts of the group have been proved to be highly diachronous. The refined chronostratigraphic framework has also allowed for a better analysis of the basin evolution through time, particularly in terms of the correlation of external stimuli that affect basin sedimentation patterns.