Volume 18 1975

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Browsing Volume 18 1975 by Keyword "ichnotaxon"

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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 "trilobite” trackways in the Table Mountain Group (Ordovician) of South Africa
    (Bernard Price Institute for Palaeontological Research, 1975) Anderson, Anne M
    A terminology for arthropod trackways is defined and the nomenclature of trace fossils is discussed briefly. Most of the trackways from the reddish sandstone Graafwater Formation are assigned to the ichnospecies Petalichnus capensis sp. nov. which includes bilaterally symmetrical walking Irails consisting of a repetition of 9-12 pairs of unifid tracks sometimes accompanied by a median drag line. These trackways are associated with hemispherical burrows Metaichna rustica gen. et sp. nov. The same animals possibly made both the trackways and the burrows, but whether or not they were trilobites is not clear.