Bruce Sidney Rubidge

Pareiasaurs were an enigmatic and diverse group of parareptilian herbivores of the middle and late Permian. Nanoparialuckhoffi was erected in 1936 but remains the least well-known member of four “dwarf” pareiasaurs that comprise Pumiliopareiasauria. After new preparation of the holotype, we present the first detailed cranial description of Nanoparialuckhoffi and a new diagnosis for the taxon based on seven autapomorphies: (1) an additional bone on the posterior margin of the cheek flange between the squamosal and quadratojugal; (2) a pyramidal-shaped parietal; (3) a very short, square lacrimal; (4) paired prepalatal foramina positioned anterolaterally on the internal premaxillary palatal flange; (5) notch on anteromedial border of the choana; (6) a ventral flange formed by the lateral margin of the internal tabulars; and (7) tabulars that extend posteriorly further than the supratemporals. We find evidence supporting a juvenile ontogenetic state for the holotype, including small skull; unossified open cranial sutures; an unossified dorsal braincase; and fewer marginal teeth than most pareiasaurs. An updated phylogeny recovers Nanoparia as a sister taxon to Provelosaurusamericanus from Brazil and remains a constituent member of Pumiliopareiasauria. Keywords: Nanoparia, Pumiliopareiasauria, Pareiasauria, Parareptilia, late Permian, Gondwana.

The main Karoo Basin of South Africa and Lesotho preserves c. 120 myr of Earth's history. The sedimentary rocks of its Karoo Supergroup record massive environmental changes from the glacial Carboniferous to desert dunes and fiery flood basalts in the Early Jurassic. From the early Permian, the Karoo Basin was gradually filled with fluvial and lacustrine deposits, and the alluvial plains were successively colonized by a diverse suite of plants and animals. The fossils of these ancient inhabitants and their behavioural traces form an astounding Gondwanan geoheritage legacy in southern Africa, providing fossil evidence for the moving lithospheric plates and the effects of four mass extinctions and their subsequent biotic recovery. Here, we present six Karoo sites of global geoscientific importance that best display that heritage, with the caveat that these sites only touch upon the Karoo riches that are available for academic research and the emerging palaeotourism industry. It is our hope that these sites will become anchor points for a sustainable geoheritage future in southern Africa.

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.

The origin and radiation of therapsids from non-therapsid synapsid ancestors (“pelycosaurs” for brevity) was a key event in the evolution of the mammalian lineage. Distinct from the problem of the ...

Pareiasaurs were relatively abundant, globally-distributed, herbivorous parareptiles of the mid to late Permian. The basal-most forms, all members of the Bradysauria, are restricted to the Guadalupian (mid-Permian) of South Africa and went extinct in the late Capitanian near the top of the Tapinocephalus Assemblage Zone. Currently four species are recognized in this group: Bradysaurus seeleyi, B. baini, Embrithosaurus schwarzi and Nochelesaurus alexanderi. These taxa have been poorly defined historically and based on a limited number of specimens, leaving the taxonomic diversity of the group open to doubt and limiting their utility in biostratigraphy. Here, we present our fourth and final contribution to improve the understanding of this group by providing a taxonomical and phylogenetic review, updated stratigraphical ranges, and updated diagnoses for each taxon within Bradysauria. Bradysaurus seeleyi is synonymized with Bradysaurus baini, resulting in three valid mid-Permian pareiasaur taxa: Bradysaurus baini, Embrithosaurus schwarzi and Nochelesaurus alexanderi. Our cladistic analysis of cranial and postcranial characters supports the monophyly of Bradysauria with five synapomorphies. Embrithosaurus schwarzi is recovered as the sister taxon to a clade containing Bradysaurus baini and Nochelesaurus alexanderi. By identifying 157 pareiasaur specimens in fossil collections we show that the Bradysauria are stratigraphically restricted to the Abrahamskraal Formation of the Beaufort Group and suggest a staggered appearance. Bradysaurus baini is first to appear, followed by Nochelesaurus alexanderi, and lastly by Embrithosaurus schwarzi. All three taxa perished during the Capitanian mass extinction, and have their highest occurrences near the top of the Abrahamskraal Formation.

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