Volume 53 2018–2019

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Now showing 1 - 5 of 12
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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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    Postcranial osteology of the neotype specimen of Massospondylus carinatus Owen, 1854 (Dinosauria: Sauropodomorpha) from the upper Elliot formation of South Africa
    (Evolutionary Studies Institute, 2019-04) Barrett, Paul M.; Chapelle, Kimberley E.J.; Staunton, Casey K.; Botha, Jennifer; Choiniere, Jonah N.
    Massospondylus carinatus Owen, 1854, from the earliest Jurassic upper Elliot Formation of South Africa, was one of the first dinosaurs to be described from Gondwana. It has been incorporated into numerous phylogenetic, palaeobiological and biostratigraphic analyses, is often viewed as an exemplar for understanding sauropodomorph anatomy and is a key taxon in studies of early dinosaur evolution. Since its initial description, numerous specimens have been referred to this species, ranging from isolated postcranial elements to complete skeletons with three-dimensional skulls. In addition,M. carinatus has been identified in areas outside of the main Karoo Basin. Surprisingly, however, there have been few attempts to define the taxon rigorously, so that the basis for many of these referrals is weak, undermining the utility of this abundant material. Here, we provide the first detailed postcranial description of the neotype specimen ofM. carinatus, use it as a basis for diagnosing the species on the basis of cranial, axial and appendicular characters, demonstrate that it represents an adult individual on the basis of osteohistology, and discuss ways in which these data can assist in providing a better understanding of Karoo-aged African dinosaur faunas.
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    A fossil chrysochlorid skull in the Ditsong National Museum of Natural History: Robert Broom’s missing specimen unearthed?
    (Evolutionary Studies Institute, 2019-04) Mason, Matthew J.; Bennett, Nigel C.; Pickford, Martin
    An unlabelled, fossilized skull of a golden mole from the Ditsong National Museum of Natural History, Pretoria, was examined through micro-computed tomography. Reconstructions show that the species in question has alveoli for nine teeth in each upper jaw, although only six teeth in total remain. The skull resembles those of the extant chrysochlorids Amblysomus and Calcochloris, which also have nine teeth, but in most respects it is closer to Amblysomus. The ear region, examined in detail, also proved to be very similar to that of Amblysomus. Damage to the teeth and palate are consistent with the brief descriptions of a fossil golden mole skull first mentioned by Robert Broom in 1948. This specimen, dating from the Plio-Pleistocene and provisionally identified as Proamblysomus antiquus, subsequently went missing. We argue that the skull described here is Broom’s lost specimen, but whether this fossil species really deserves generic distinction from extant groups remains unclear.
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    The inner craniodental anatomy of the Papio specimen U.W. 88-886 from the Early Pleistocene site of Malapa, Gauteng, South Africa
    (Evolutionary Studies Institute, 2019-04) Bouchet, Florian; Ribéron, Alexandre; Heaton, Jason L.; Hoffman, Jakobus; Bam, Lunga; Jakata, Kudakwashe; Tawane, Mirriam; Tenailleau, Christophe; Zipfel, Bernhard; Beaudet, Amélie
    Cercopithecoids represent an essential component of the Plio-Pleistocene faunal assemblage. However, despite the abundance of the cercopithecoid fossil remains in African Plio-Pleistocene deposits, the chronological and geographic contexts from which the modern baboons (i.e. Papio hamadryas ssp.) emerged are still debated. The recently discovered Papio (hamadryas) angusticeps specimen (U.W. 88-886) from the Australopithecus sediba-bearing site of Malapa, Gauteng, South Africa, may represent the first modern baboon occurrence in the fossil record. Given the implication of U.W. 88-886 for the understanding of the papionin evolutionary history and the potential of internal craniodental structures for exploring evolutionary trends in fossil monkey taxa, we use X-ray microtomography to investigate the inner craniodental anatomy of this critical specimen. Our goal is to provide additional evidence to examine the origins of modern baboons. In particular,we explore (i) the tissue proportions and the dentine topographic distribution in dental roots and (ii) the endocranial organization. Consistent with the previous description and metrical analyses of its external cranial morphology, U.W. 88-886 shares internal craniodental anatomy similarities with Plio-Pleistocene and modern Papio, supporting its attribution to Papio (hamadryas) angusticeps. Interestingly, average dentine thickness and distribution in U.W. 88-886 fit more closely to the extinct Papio condition, while the sulcal pattern and relative dentine thickness are more like the extant Papio states. Besides providing additional evidence for characterizing South African fossil papionins, our study sheds new light on the polarity of inner craniodental features in the papionin lineage.
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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.