Volume 18 1975

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    Palaeontologia africana Volume 18
    (Bernard Price Institute for Palaeontological Research, 1975)
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    Planktonic foraminifera and calcareous nannofossils at the Cretaceous-Tertiary contact in Zululand
    (Bernard Price Institute for Palaeontological Research, 1975) Stapleton, R P
    Assemblages of planktonic foraminifera and calcareous nannofossils for the Maestrichtian and Danian of Zululand are listed and illustrated. The Globotruncana gansseri and G. mayorensis foraminiferal zones are present in the Maestrichtian. The Globigerina triloculinoides and Globorotalia compressa foraminiferal subzones are present in the Danian. The Maestrichtian in this area cannot be subdivided on the basis of calcareous nannofossils. Danian nannofossil zones present are those of Cruciplacolithus tenuis and Chiasmolithus danicus . The Cretaceous-Tertiary faunal extinctions are briefly discussed and it is concluded that lowered temperatures were a factor in this extinction.
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    A problematical element in the Glossopteris flora of Vereeniging
    (Bernard Price Institute for Palaeontological Research, 1975) LeRoux, S F
    An unusual element, not previously recorded from the mixed Glossopteris Flora of Vereeniging, is described here. The type material was obtained from a rich fossiliferous zone, previously described by the author (Le Roux, 1963, pp. 1-2). The material available for study consists of a single specimen of an incomplete frond preserved in the form of an impression in fine-grained laminated clay.
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    Trace fossils in the Ecca of northern Natal and their palaeoenviromental significance
    (Bernard Price Institute for Palaeontological Research, 1975) Hobday, D K; Tavener-Smith, R
    Because of the rarity of body fossils in the Ecca Group fossil burrows, tracks and trails are of potential value in supplementing primary sedimentary evidence concerning the palaeoenvironmental factors of bathymetry, energy level and food supply. The three most important ichnogenera are Skolithos, Corophioides and Scolicia. The first two are restricted to the upper portions or Middle Ecca upward-coarsening regressive cycles attributed to delta progradation. They arc representatives of Seilacher's (1967) Skolithos and Glossijungites communities, indicating shallow water conditions with diastems. Scolicia occurs at lower levels in the cycles and corresponds to Seilacher's deeper water Cruziana community. Meandering trails Helminthopsis and Taphrhelminthopsis in the Lower Ecca belong to Seilacher's deep water Nereites community. Less common ichnogenera include the U-burrows Diplocraterion and Rhizocorallium. It has proved impossible positivelv to identify many trace fossils such as short ramifying burrows, chevron trails, dumbbell-shaped surface impressions, digitate tracks and problematic elliptical casts. Trace fossils have not been recognised with certainty in the fluviatile deposits which comprise the bulk or the coal-bearing strata of northern Natal.
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    The morphology and relationships of Youngina capensis Broom and Prolacerta broomi Parrington
    (Bernard Price Institute for Palaeontological Research, 1975) Gow, Chris E
    Comprehensive descriptions of the osteology of Youngina capensis Broom and Prolacerta broomi Parrington are presented. New details of the braincase of Proterosuchus fergusi Broom are given as these became necessary for comparative purposes. It is suggested that the initial radiation of sauropsid reptiles was a Permian event as yet poorly documented. The phylogenetic position of Youngina forward and backward in time cannot be narrowly defined, though certain characters seem specifically to preclude it from lizard ancestry. Prolacerta, on the basis of tooth implantation, braincase morphology and postcranial anatomy is shown to be closest to the proterosuchian thecodonts. It is very definitely not concerned with lizard origins, but would on available evidence seem to be a perfectly good ancestor for the middle Triassic forms Macrocnemus and Tanystropheus which latter must cease to be regarded as lizard ancestors. We have here a rather distinct reptilian lineage which branched off from common ancestral stock just prior to the advent of archosaurs.