Palaeontologia africana

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ISSN (print): 0078-8554 ISSN (electronic): 2410-4418 For queries regarding content of Palaeontologia africana collections please contact Jonah Choiniere by email : jonah.choiniere@wits.ac.za or Tel : 011 717 6684

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    Biostratigraphic refinement of tetrapod-bearing beds from the Metangula Graben (Niassa Province, Mozambique). New radiometric dating and the first Lower Triassic tetrapod fossils from Mozambique
    (Evolutionary Studies Institute, 2020-12) Aráujo, Ricardo; Macungo, Zanildo; Smith, Roger M H; Tolan, Stephen; Angielczyk, Kenneth D; Crowley, James; Milisse, Dino; Mugabe, João
    Numerous fossils of the toothed dicynodont Endothiodon have been collected previously from the Permian K5 formation of the Metangula Graben (Niassa, Mozambique). However, no identifiable vertebrate fossils have been reported from other stratigraphic units in the basin. Here we report likely Triassic tetrapod remains from the base of the Fubué Formation some 700 stratigraphic metres above the dated K5 Formation. We present anatomical comparisons and a phylogenetic analysis that confirm that they have close affinities to the well-known Early Triassic dicynodont therapsid Lystrosaurus. Thus, the Metangula Graben can now join the few regions in the world that preserve terrestrial tetrapod fossils from before and after Permian-Triassic mass extinction event, giving it the potential to provide further insights into the evolution of terrestrial organisms during this major biotic crisis. We present an updated geological section and paleoenvironmental interpretations, as well as the first assessment of the vertebrate taphonomy of the K5, K6, Mount Lilonga, and Fubué Formations. We also report the first radiometric dates for the K5c member of the K5 formation. The K5c has a maximum depositional age of 258.85 ± 0.41 Ma and is thus older than previously thought, falling near the boundary between the Lycosuchus-Eunotosaurus and Tropidostoma-Gorgonops subzones of the Endothiodon Assemblage Zone, rather than being coeval with the Cistecephalus Assemblage Zone.
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    First occurrence of the dicynodont Digalodon (Therapsida, Anomodontia) from the Lopingian upper Madumabisa Mudstone Formation, Luangwa Basin, Zambia
    (Evolutionary Studies Institute, 2019-04) Angielczyk, Kenneth D.
    Digalodon is a rare emydopoid dicynodont first described from upper Permian rocks in the Karoo Basin of South Africa. During fieldwork in the upper Madumabisa Mudstone Formation of the Luangwa Basin (Zambia) in 2014, a small dicynodont skull was discovered that conforms very well to the recently revised diagnosis of Digalodon rubidgei, although some minor differences between the Zambian and South African specimens are apparent. The Zambian occurrence of Digalodon expands the known geographic range of the genus, which was previously limited to a small set of localities in the vicinity of the town of Graaff-Reinet (Eastern Cape). Based on historical specimens, Digalodon is thought to have a comparatively short stratigraphic range in the Balfour Formation that spans the boundary between the Cistecephalus and Daptocephalus assemblage zones. This observation may allow refinement of biostratigraphic correlations between the Karoo and Luangwa Basins, but discovery of more precisely-provenanced specimens in the Karoo is needed to fully assess Digalodon’s biostratigraphic utility.
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    A new dicynodont (Anomodontia: Emydopoidea) from the terminal Permian of KwaZulu-Natal, South Africa
    (Evolutionary Studies Institute, 2019-04) Kammerer, Christian F.
    A new taxon of dicynodont (Thliptosaurus imperforatus gen. et sp. nov.) is described based on a dorsoventrally-crushed skull from latest Permian (upper Daptocephalus Assemblage Zone) strata in KwaZulu-Natal, South Africa. Thliptosaurus is distinguished from all other dicynodonts by an elongate intertemporal bar with broad dorsal exposure of the parietals but apparently no pineal foramen. Absence of the pineal foramen in dicynodonts is exceedingly rare; the only other taxa which exhibit this feature either have substantially broader (Kawingasaurus fossilis) or narrower (Kombuisia frerensis) intertemporal regions. Inclusion of Thliptosaurus in a phylogenetic analysis of dicynodonts recovers it as a kingoriid emydopoid, a position supported by its anteriorly-restricted pterygoid keel, elongate, curved anterior process of the lacrimal, relatively posterior position of the median pterygoid plate, and occlusion of the mandibular fenestra by a lateral plate of the dentary. Intriguingly, even in the other kingoriids which retain a pineal foramen (Dicynodontoides spp. and Kombuisia antarctica), this structure is reduced in size relative to other dicynodonts, suggesting that the pineal eye was less important for thermoregulatory activity in this clade than in other anomodonts. Although part of a local fauna including taxa that are otherwise widespread in the Karoo Basin (Daptocephalus, Lystrosaurus), the unique presence of Thliptosaurus in the relatively poorly-sampled Daptocephalus Assemblage Zone deposits of KwaZulu-Natal suggests that this region may preserve endemic taxa, and should be prioritized for future fieldwork.
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    Histological evidence of trauma in tusks of southern African dicynodonts
    (Evolutionary Studies Institute, 2019-01) Whitney, Megan R.; Tse, Yuen Ting; Sidor, Christian A.
    Dicynodonts were a clade of globally-distributed therapsids known for their abundance in the fossil record and for surviving the Permo-Triassic mass extinction. The group had distinctive dental adaptations including a beak and, in many species, paired maxillary tusks. The function of these tusks has long been of interest, yet remains poorly understood.We report here on two instances of unusual morphology in tusk dentine from specimens of: 1) Lystrosaurus from the Karoo Basin of South Africa and, 2) an unidentified dicynodontoid from the Luangwa Basin of Zambia. In both, the cross-sectional shape of the tusk root is lobed and infolded, which histological features suggest is a result of abnormal dentine deposition. We infer that this abnormal morphology is likely the consequence of trauma given its reparative nature and structural similarities to trauma-related morphologies reported in the tusks of modern elephants. This study demonstrates that histological sampling of dicynodont tusks can shed light on the biology of this important clade of therapsids.
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    The first skeletal evidence of a dicynodont from the lower Elliot Formation of South Africa
    (Evolutionary Studies Institute, 2018) Kammerer, Christian F.
    Historical fossil specimens from the lower Elliot Formation are identified as representing a large-bodied dicynodont, the first known from skeletal material in the Late Triassic of South Africa. Although fragmentary, these fossils differ from all other known Triassic dicynodonts and are here described as a new taxon, Pentasaurus goggai gen. et sp. nov. Pentasaurus can be distinguished from other Triassic dicynodonts by a number of mandibular characters, most importantly the well-developed, unusually anteriorly-positioned lateral dentary shelf. Phylogenetic analysis indicates that Pentasaurus is a placeriine stahleckeriid. Placeriines include the latestsurviving dicynodonts but their remains are primarily known from the Northern Hemisphere, with their only previously-known Southern Hemisphere representative being the Middle Triassic Zambian taxon Zambiasaurus. The discovery of a placeriine in the Late Triassic of SouthAfrica supports recent proposals that local climatic conditions, not broad-scale biogeographic patterns, best explain the observed distribution of Triassic tetrapods. The tetrapod fauna of the lower Elliot Formation is highly unusual among Triassic assemblages in combining ‘relictual’ taxa like dicynodonts and gomphodont cynodonts with abundant, diverse sauropodomorph dinosaurs.
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    The skeleton of the Triassic anomodont Kannemeyeria wilsoni Broom
    (Bernard Price Institute for Palaeontological Research, 1975) Cruickshank, Arthur R I
    The general structure of the post-cranial skeleton of many Triassic anomodonts is now well known, but in Africa that of the stratigraphically important Lower Triassic (? Scythian) genus Kannemeyeria is known only from dissociated elements. A brief description is given for the first time of an almost complete skeleton ascribed to this genus. The environment of deposition is described briefly. The locality of the type species of the genus is also noted .
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    A detailed description of the internal structure of the skull of Emydops (Therapsida: Dicynodontia)
    (Bernard Price Institute for Palaeontological Research, 1993) Fourie, Heidi
    A detailed morphological study of two skulls of Emydops was undertaken by using the serial grinding technique. Graphic reconstructions of various aspects of the skulls were made. The internal structures are described in detail and compared to other small dicynodonts such as Eodicynodon, Pristerodon, Cistecephalus and Diictodon. Emydops and Cistecephalus show more advanced features in common with each other than with other dicynodonts. The structure of the skull of Emydops conforms within the limits of variation known for this genus, to descriptions given in the literature. It was found that Emydops differs from other dicynodonts in that the parasphenoid has a definite suture with the pterygoid anterior to the pterygoid-basisphenoid suture, instead of passing between the pterygoids without contacting them, as reported by Olson (1944).