A phosphatic stromatolite (Ilicta cf. composita Sidorov) from the Middle Cambrian,northern Australia

Phosphatic stromatolites from the early Middle Cambrian (Ordian) of the Georgina Basin are described and identified as Ilicta cf. composita Sidorov. Based on Öpik's interpretation of the early Middle Cambrian, the age of the Georgina Basin specimens is similar to that of the type specimens described from the late Early Cambrian of Eastern Siberia. Phosphatic stromatolites occur at the base of dolomitized and partially silicified bioherms up to 4 m thick. The phosphatic forms overlie impermeable, cemented pavement surfaces which were covered by stratiform stromatolites from which rose columnar forms up to 5 cm in height. The stromatolites were phosphatized by penecontemporaneous diagenetic reactions that took place just below the sediment water interface and above the impermeable substrates.     

Ordovician biostratigraphy of the Canning Basin,Western Australia

Six biostratigraphically distinct faunas based largely on trilobites and graptolites are defined from the Lower to Middle Ordovician limestone, sandstone and shale sequence of the Canning Basin. They range in age from the Tremadoc (fauna 1), through the Arenig (faunas 2, 3) to the Llanvirn (faunas 4–6).     

The radiation of early Silurian spiriferide brachiopods,with new taxa from the Llandovery of Iran

Popov, L.E. & Cocks, L.R.M., 2013. The radiation of early Silurian spiriferide brachiopods, with new taxa from the Llandovery of Iran. Alcheringa 38, 560–566. ISSN 0311–5518.

Although there were Late Ordovician spiriferides in the superfamily Cyrtioidea, namely Eospirifer and Odakella, only the former genus survived the terminal Ordovician extinction, and only Eospirifer is known from the earliest Llandovery (Rhuddanian). However, in the succeeding mid-Llandovery (Aeronian), the spiriferides radiated to include not only more species within Eospirifer and Striispirifer in the Eospiriferidae, but also the new genus Iranospirifer described here, which is the earliest representative of the other family within the superfamily, the Hedeinopsidae. The Ordovician species were confined to the South China continent and the Boshchekul volcanic island arc in Kazakhstan, but by the Aeronian the superfamily had spread westwards to various other continents, including the main Gondwanan superterrane (which included Iran) in the early Aeronian, and Avalonia-Baltica and Laurentia in the late Aeronian. The new species Eospirifer ghobadiae and Iranospirifer qarabilensis are both described from the lower Aeronian of Iran, and there is a note on the Aeronian rhynchonellide Stegocornu, which is endemic to Iran and nearby areas.

Leonid E. Popov [lepbarry@yahoo.co.uk; leonid.popov@museumwales.ac.uk] Department of Geology, National Museum of Wales, Cathays Park, Cardiff CF10 3NP, UK. L. Robin M. Cocks [r.cocks@nhm.ac.uk], Department of Earth Sciences, The Natural History Museum, Cromwell Road, London SW7 5BD, UK. Received 29.5.2013, revised 12.7.2013, accepted 21.7.2013.