Browsing by Author "Fordyce, Nicholas"

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    Cold case files : palaeoforensic and taphonomic study of the Mamafura dicynodont from the end permian
    (2010) Fordyce, Nicholas; Chinsamy-Turan, Anusuya; Smith, Roger
    Dicynodonts were non-mammalian herbivorous therapsids (mammal-like reptiles) that flourished world-wide during the Permian and Triassic Periods. They are nowhere more abundant than in the rock strata of the Karoo basin in South Afiica. Taphonomy, the transition from biosphere to lithosphere, is of great geological and biological significance and has provided remarkable insight into palaeoenvironments. A partially articulated dicynodont that has been fossilised alongside an unidentified predator tooth shows evidence of predation and is analysed here. The dicynodont is possibly Oudenodon grandis and was most likely drowned after which it was scavenged from by a gorgonopsian predator, Aelurognathus. The fossil is important as it provides further insight into the ecology of the Late Permian and it enhances our taphonomic understanding.
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    Evidence of a therapsid scavenger in the Late Permian Karoo Basin, South Africa
    (2012) Fordyce, Nicholas; Smith, Roger; Chinsamy, Anusuya
    Dicynodonts are an extinct group of herbivorous non-mammalian therapsids (‘mammal-like’ reptiles) that are widely known from terrestrial Permo-Triassic strata throughout Pangaea. Dicynodont fossil remains are common within the Late Permian Beaufort Group of the Karoo Basin in South Africa. A large, partially articulated dicynodont skeleton recovered from the Tropidostoma Assemblage Zone is taphonomically important in having an unusual disarticulation pattern, bone surface punctures and a broken tooth of an unidentified carnivore associated with it. Here we report on the nature of the bone damage, and the identity of the carnivore that lost a canine tooth whilst scavenging the dicynodont carcass. The morphological characteristics of the serrations on the unidentified tooth were compared with those of contemporaneous carnivores, the gorgonopsians and therocephalians. Scanning electron microscopy analysis of a silicone cast of the unidentified tooth revealed distinctive 0.5-mm square-shaped serrations. Our comparative assessment of the tooth size, curvature, cross-sectional shape and morphology of the serrations revealed that the unidentified canine most closely matched Aelurognathus, a gorgonopsian known from the same assemblage zone.
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    Muddy memories : environmental change at Hluhluwe Imfolozi Game Reserve, KwaZulu-Natal, South Africa - evidence from diatoms
    (2010) Fordyce, Nicholas; Gillson, Lindsey; Kirsten-Sardinha, Kelly
    Diatoms are microscopic algae found in almost all aquatic environments. They are habitat specific and have silica frustules which preserve well in sediments. They have been used extensively to provide a multitude of palaeoecological data relating to pH, nutrient loads and water levels. Here, the diatoms in a lake sediment core from Hluhluwe-Imfolozi, South Africa, are analysed to show fluctuations in littoral to benthic taxa, and brackish to freshwater taxa as indicators of lake level changes over time. Changes in lake level act as a proxy for warm/dry or cold/wet periods over time. During the last 240 years lake levels have remained consistently low but nevertheless indicate four alternating periods of cold/wet and warm/dry climate. From c. A.D. 1770 (the last few decades of the Little Ice Age) to the c. A.D. 1840 the climate was cool and wet, but nonetheless gradually warmed up and became drier. From c. A.D. 1840 through to c. A.D. 1920 a there was a gradual increase in temperature and corresponding decrease in rainfall. Then, from c. A.D. 1920 till c. A.D. 1980 there was another colder, wetter period. Finally, very recently, from around c. A.D. 1980 till the present day, Hluhluwe-Imfolozi has experienced warmer, drier conditions once. Pollution-tolerant diatoms increase during the last 100 years and indicate eutrophication of the lake, a consequence of anthropogenic activity in the region. The diatom sequence from Phindiswene provides a high resolution climatic proxy for the critical period covering the latter stages of the Little Ice Age (LIA), post LIA warming, and recent increasing anthropogenic impacts.