John Pickett

Ordovician faunas and biostratigraphy in the Gunningbland area, central New South Wales, Australia

The Billabong Creek Formation and overlying Gunningbland Formation within the Northparkes Group in the Gunningbland area, 28 km west of Parkes, range in age from late Darriwilian (late Middle Ordovician) to late Eastonian (middle Late Ordovician). These strata provide the most complete sequence through this interval in the central Lachlan Orogen in New South Wales. A biostratigraphic zonation spanning the Darriwilian to Gisbornian is proposed, employing conodonts and corals. This supplements the existing coral/stromatoporoid, brachiopod and trilobite faunal assemblages defining Eastonian and Bolindian shelly fossil zones. The Pygodus anserinus Zone (late Darriwilian) in the basal Billabong Creek Formation is succeeded by the Foerstephyllum-Billingsaria-Stratodictyon Assemblage-Zone (of Gisbornian age) in the middle Billabong Creek Formation. A further five Assemblage-Zones extending through the Eastonian succession are formally defined to replace the existing shelly fossil ‘faunas’. New coral species described are Billingsaria domica, Eofletcheria subcerioidea, Foerstephyllum nelungaloo, and ?Paleoalveolites explanatus; a possible new species of the conodont Eoplacognathus is described, but not formally named.

Vaceletia progenitor, the first Tertiary sphinctozoan (Porifera)

Vaceletia progenitor sp. nov., the first sphinctozoan of Tertiary age, is described from the Late Eocene Pallinup Siltstone of Western Australia. The name Vaceletia is introduced as a nomen novum for Neocoelia Vacelet (1977), the first extant sphinctozoan, preoccupied by Neocoelia McKellar (1966).

Conodont assemblages from the Cobar Supergroup (Early Devonian), New South Wales

Conodont assemblages identified as representing the Early Devonian zones of Icriodus woschmidti, Pedavis pesavis and Polygnathus gronbergi have been obtained from limestone horizons within the Cobar Supergroup. These assemblages provide the first accurate correlation for any horizons within the Supergroup. Age determinations of the Rookery Limestone and White Tank Limestone Members of the Meryula Formation suggest the presence of strike faulting not detected by field mapping. Ozarkodina druceana nom. nov. (pro Spathognathodus philipi Druce 1970) and Delotaxis tenuistriata sp. nov. are discriminated on the basis of their apparatuses of distinctive elements.

The succession of early carboniferous coral faunas in eastern Australia and China

The stratigraphic distribution of coral species in the Carboniferous of eastern Australia is re-examined in the light of advances in bio- and lithostratigraphy, enabling recognition of five informal coral faunas. Coral assemblages persist longer in Queensland than in New South Wales, a reflection of the southward migration of the continent and a meridional trend of the eastern seaboard. The area formed a single biogeographic province. Distribution of coral species in the Peoples Republic of China is reviewed and stratigraphic zonations are summarised. Four biogeographic provinces are recognised within China. Similarities and differences in coral assemblages between the four provinces are found to be in general agreement with a proposed Early Carboniferous palaeogeography.

Jurassic Invertebrates from the Himalayan Central Gneiss

Poorly preserved scleractinian corals and cephalopod molluscs occur in metamorphosed and foliated limestones in the Himalayas of northwest India. The nautiloid Cenoceras and macrocephalitid ammonites indicate a Middle Jurassic age. The fossils occur within a zone of high grade metamorphic rocks known as the Central Gneiss, previously regarded as an axial massif of Precambrian basement. Most palaeogeographic reconstructions feature this zone as a prominent topographic arch or ‘Himalayan Ridge’ which arose in the late Precambrian or early Palaeozoic and, through periodic rejuvenation, persisted throughout the Phanerozoic. Many workers believe that the ‘Himalayan Ridge’ constituted an effective barrier to north-south faunal migration because the terrains of sedimentary rock which flank the Central Gneiss contain quite different faunas. The Jurassic fossils provide new stratigraphic evidence that the tectonic events which generated the Central Gneiss are relatively young, and this, together with structural co...

A Late Pleistocene coral fauna from Evans Head, N.S.W.

An assemblage of hermatypic scleractinian corals occurring landwards of the Pleistocene sandy Inner Barrier system has been referred to the last interglacial period. It comprises at least 20 species, many of which are in growth position, and is accompanied by a substantial association of molluscans. The richness of the assemblage is indicative of good access of oceanic waters at the time of its formation, so the deposit predates barrier emplacement. The coral occurrences are compared with present-day southern ranges of the scleractinian species (all extant), and the implications for climatic and sea-level conditions in the last interglacial are discussed. A sea-level stand of 4–6 m above that at present obtaining (in accord with Marshall & Thom, 1976) and a climatic shift towards a cooler regime equivalent to a minimum of 2° of latitude are concluded.

Webbygnathus, a new Late Ordovician conodont genus from New South Wales

The new conodont Webbygnathus munusculum gen. et sp. nov. is described from Eastonian (early Late Ordovician) strata from the central part of the Parkes Zone of the Lachlan Fold Belt and the New England Fold Belt in New South Wales. In the type area south of Gunningbland, central New South Wales, the genus occurs associated with macrofossils of the coral/stromatoporoid assemblage Fauna II (early Eastonian or Ea2); in the New England region it has been obtained from strata on both sides of a major structural feature, the Peel Fault, the associated conodont assemblages indicating an age equivalent to that of coral/stromatoporoid assemblage Fauna III or late Eastonian (Ea3). The apparatus of this species, as presently known, comprises two pectiniform elements, one stellate with a four-rayed basal cavity, the other fundamentally pastinate, with a three-rayed basal cavity.