High latitude Gondwanan famennian biodiversity patterns : evidence from the South African Witpoort Formation (Cape Supergroup, Witteberg Group)
Reassessment of the stratigraphic position of the Waterloo Farm black shale from Grahamstown, South Africa, revealed that it is situated in the uppermost Witpoort Formation, as opposed to the middle of the Witpoort Formation as previously reported. This argillaceous unit appears to be contemporaneous with globally correlated black anaerobic sediments intimately associated with the Hangenberg Extinction, the final and most important pulse of the end Devonian extinction event. The Waterloo Farm fauna is one of only seven significant faunas from the end Famennian, and one of only two from Gondwana. The other one, from Morocco, was situated in the palaeotropics of northern Gondwana whereas Waterloo Farm, situated near the palaeo South Pole, provides the only high latitude locality. Extensive fieldwork resulted in 511 catalogued fossil fish specimens. These comprise at least 21 taxa of which least 2 are agnathan, 7 placoderm, 4 acanthodian, 2 chondrichthyan, 1 actinopterygian and 5 sarcopterygian. Sarcopterygians include an onychodont, a coelacanth, a tristichopterid and an isolated cleithrPriscomyzon riniensis, the oldest lamprey, exhibits many of the key specialisations of modern lampreys including a large oral disc, circumoral teeth and a branchial basket. Analysis of Priscomyzon revealed that lampreys are ancient specialists that, having acquired key specialisations before the end of the Devonian period, survived with relatively little change for 360 million years. Shark fossils include Antarctilamna ultima (sp. nov.), a new species of a Gondwanan genus previously considered to have gone extinct before the late Devonian, and Plesioselachus doryssa. These taxa are basal to the crowngroup chondrichthyan radiation and provide insight into the primitive condition of chondrichthyans. A new coelacanth species, Paradiplocercides kowiensis (gen. et sp. nov.), represents one of the most completely preserved early coelacanths and offers insights into the early diversification
Computer Program, English, 2012-05-14
University of the Witwatersrand, 2012-05-14