The Memoirs series publishes peer reviewed papers on all aspects of palaeontology and its applications in the earth and biological sciences, including taxonomy, biostratigraphy, vertebrate and invertebrate palaontology, palaeoichnology, palaeobotany, palynology, palaeobiology, palaeoecology, palaeobiogeography and biogeochemistry amon others. The Memoir series is designed for longer monographic treatments, but will also consider thematic sets of papers and commonly publishes conference proceedings.

Trilobites from the Lower Cambrian succession at Angorichina in the eastern Flinders Ranges, South Australia, are described. Silicified material from the Mernmerna Formation reveals the presence of a new assemblage from the 'Pararaia bunyerooensis' Zone, including the eponymous species, 'Yorkella' aff. 'australis, Eoredlichia' sp. 'Redlichia' sp., and the new species 'Wutingaspis euryoptilos' and 'Yunnaocephalus macromelos'. Trilobites of the 'Pararaia bunyerooensis' Zone show a strong affinity with those from the Yu'anshan Member of the Heilinpu Formation in Chengjiang and Jinning Countries, Yunnan Province, southwest China. The 'Pararaia bunyerooensis' Zone is correlated with the 'Yunnanocephalus' Assemblage subzone (upper 'Eoredlichia-Wutungaspis' Zone) of the Chiungchussuan (=Qiongzhusian) Stage of China. Additional trilobites from Angorichina include 'Elicicola calva' from the Wilkawillina Limestone, 'Estaingia occipitospina' (Jell) new combination form the Oraparinna Shale, and 'Redlichia guizhouensis' Zhou from the Wirrealpa Limestone. Australian Early Cambrian trilobite biozonation is reviewed, with discussion of distinct assemblages within the 'Pararaia janeae' Zone that have the potential for zonal subdivision, and evidence to support the placement of the northern Australian Ordian/Early Templetonian Stage within the late Early Cambrian. A possible paedomorphic lineage between 'Pararaia bunyeriiensis' and 'P. janeae' is proposed. Adult specimens of 'P. janeae' retain juvenile characteristics of the progenitor 'P. bunyerooensis'. Retardation in onset of maturity in 'P. janeae' resulted in the attainment of a larger adult size than in P. bunyerooensis', indicating the former species evolved via neoteny.

Two new late Early Ordovician orthide brachiopods, 'Celsiorthis bulancis' n.gen. and n.sp. and Alocorthis psygmatelos n.gen. and n.sp., are described from the Tabita and Pingbilly formations at Mount Arrowsmith, northwestern New South Wales. The associated conodont assemblage from the succession at Mount Arrowsmith indicates a late Bendigonian to Chewtonian age for the brachiopod bearing horizons.

Copper isotope fractionation factors have been determined experimentally at temperatures of 250 and 300 °C for fluid salinities of 1, 3, 5 and 7 molal Cl-, and starting acidity of 0, 0.01, 0.1, 0.2 and 0.6 molar HCl. The experiments, which follow a partial dissolution of natural chalcopyrite in a hydrothermal fluid from 7 to 30 days, yield a significant range of leached copper-residual chalcopyrite isotopic fractionations. These appear to be pH, temperature and salinity dependent, with pH showing the greatest apparent control over the magnitude of fractionation. For weakly acidic conditions, preferential incorporation of the light isotope into the leached phase(s) generally occurred. Experiments gained a maximum fractionation magnitude at intermediate pH (4-7), where the leached copper-chalcopyrite fractionation magnitude reached to - 1‰, depending on fluid salinity and temperature. Fractionation decreased at higher and lower solubility (pH) conditions. The highest pH experiments showed a small positive fractionation (approx. + 0.2 to 0.3‰). Limited reproducibility of the experiments is related to unconstrained physicochemical conditions (primarily pH and fO₂). A major control on the fractionation magnitude appears to be the degree of partitioning of Cu between vapor and liquid phases, which is controlled by pH and salinity. The copper-bearing vapor species permitting significant mass transfer to the vapor apparently differ with salinity and temperature. Under certain experimental conditions one or more vapor species forms and produces significant isotopic fractionation between the copper in the liquid and copper in the vapor. The experiments indicate that the likelihood of observing significant isotopic fractionation in hypogene ore forming systems depends on the pH of the mineralizing fluid and the controls over partitioning of Cu between a vapor and liquid phase.

An early Late Cambrian (late Mindyallan-Idamean) trilobite fauna is described from limestone bodies in the Dolodrook River area, eastern Victoria. Seven taxa are referred to previously described species: 'Innitagnostus inexpectans' (Kobayashi, 1938), 'Pseudagnostus idalis' Öpik, 1967, 'Corynexochus plumula' Whitehouse, 1939, 'Rhyssometopus thielei' (Chapman, 1911), 'Eugonocare tessellatum' Whitehouse, 1939, 'Protemnites magnificans' Shergold & Webers, 1992 arid 'Meteoraspis etheridgei' (Chapman, 1911), seven taxa are left under open nomenclature: 'Idolagnostus ?agrestis' Öpik, 1967, Peratagnostus aff.'invalidus' (Lu & Lin, 1989), 'Amrnagnostus' sp., 'Tomagnostella' sp., 'Pterocephaliid?' gen. et sp. indet., Tsinaniid gen. et sp. indet. 1 and Tsinaniid gen. et sp. indet. 2, and one represents a new species: 'Mindycrusta oepiki' sp. nov. 'Protemnites' Whitehouse, 1939 is considered to be a senior subjective synonym of 'Prismenaspis' Henderson, I976a. Two trilobite assemblages are recognised: the 'Protemnites' Assemblage aid the 'Mindycrusta' Assemblage. The Protemnites Assemblage is interpreted as representing an autochthonous assemblage inhabiting a moderate to high energy, inner shelf (peritidal) environment. The Mindycrusta Assemblage represents a parautochthonous assemblage inhabi ing a low to moderate energy, open ocean-facing, outer shelf to upper slope environment.

Two new trilobites from the Lower Cambrian Emu Bay Shale Lagerstätte at Big Gully, Kangaroo Island, are described. 'Megapharanaspis nedini' gen. et sp. nov. is placed in the Megapharanaspidae, a new family of the Emuelloidea. 'Holyoakia simpsoni' sp. nov. represents the first occurrence of the genus outside Antarctica, providing further confirmation of the close faunal affinity between Cambrian trilobite faunas from Australia and East Antarctica. New specimens of 'Redlichia takooensis' are documented that provide new morphological information, including a description of the rostral plate and hypostome.

Shells of 'Oikozetetes' and isolated halkieriid sclerites from a section of the lower Cambrian Mernmerna Formation in the Flinders Ranges, South Australia, are tentatively considered as being derived from the same scleritome. Details of shell morphology and the possible combination of biomineralized shell and sclerites suggest that 'Oikozetetes', if interpreted correctly, is closely related to 'Halkieria'. A new interpretation of 'Oikozetetes' shell morphology, in addition to the first report of paired muscle scars on the interior surface, sheds new light on the possible functional morphology of halkieriid shells and the means of attaching the shell to the body. The occurrence of 'Oikozetetes' in South Australia extends its biostratigraphic range to the lower Cambrian and biogeographic range to East Gondwana.

Radiolarian discoveries indicate that deep-marine conditions prevailed in central Tibet from the early Middle Jurassic until well into the Early Cretaceous (late Hauterivian-early Aptian; 131-121 Ma) and help to constrain the temporal extent of oceanic conditions along the Bangong-Nujiang suture. These new fossils occur in chert or siliceous mudstone blocks associated with the Lagkor Tso ophiolitic mélange. Basin inversion associated with closure of Mesotethys between the Qiangtang and Lhasa terranes was accompanied by mélange formation and predated regionally widespread deposition of overlying shallow-marine late Aptian-Albian orbitolinid limestones.