Internal moulds of complete shells, including conch and associated opercula, of the hyolith 'Triplicatella disdoma' from Cambrian Series 2, Stages 3-4 of South Australia are described. The conch of 'T. disdoma' is shown to be narrow and cone-shaped, and with a rounded triangular cross-section. The conch shows a gentle dorsal curvature in lateral view. The fossils lack evidence of helens, and the operculum was smaller than the apertural diameter of the conch and could be withdrawn a short distance into the conch. 'Triplicatella' was probably closely related to orthothecid hyoliths.

An assemblage of bivalved arthropods from the Memmema Formation on 'Angorichina' Station in the Flinders Ranges, South Australia contains six bradoriid species, one phosphatocopid, and the spine of 'Isoxys'. The assemblage includes several species that facilitate correlation with the Stansbury Basinof South Australia, but also with faunas from other Cambrian palaeocontinents, including Antarctica, China and Laurentia. One new taxon, 'Spinospitella coronata' gen.et sp.nov. is described. This species is represented by both complete shields and numerous characteristic spines and fragments, fuelling a general discussion on the possible identification of bradoriid remains among the numerous problematic 'small shelly fossils' of the Lower and Middle Cambrian.

Mode of preservation and method of recovery strongly influences our understanding of the life habits of extinct organisms. Bradoriid arthropods were abundant, and diverse members of early Cambrian ecosystems and most life reconstructions display these animals with the two shields of the carapace open in a 'butterfly' configuration. This favoured reconstruction is largely based on the abundance of 'crack-out' specimens preserved in this position (e.g. 'Kunmingella' from the early Cambrian of China). In contrast, large collections of acid processed bradoriids from the Arrowie Basin of South Australia (Cambrian Stage 3) are preserved with a narrow gape at the ventral margin or completely closed with the carapace folded along the dorsal midline. The relative abundance of conjoined, closed (or partially closed) specimens from the lower Cambrian Hawker Group succession suggests that at least some bradoriid taxa were capable of withdrawing appendages and tightly closing the shields, challenging the common view that the majority of bradoriids usually held their carapaces open in a 'butterfly' configuration during life. New data show that layers of the bradoriid carapace are continuous through the dorsal fold with no evidence for complex articulating structures as in ostracod hinges. The relatively pliable, sclerotized or lightly mineralized calcium phosphate composition of the carapace and the simple, flexible dorsal fold facilitated opening and closing of the shields. Despite not being closely related, ostracods share close biomechanical and ecological similarities with bradoriids. The evolution of more complex articulating hinge structures - together with well-developed musculature - in ostracods during the Early Ordovician, may have provided more efficient means for shield articulation and movement, thus promoting the ecological success of ostracods throughout the Phanerozoic.

The lower Cambrian sediments of the Flinders Ranges, South Australia can be divided into three sequence sets. They rest unconformably on the Ediacaran succession. Sequence set ϵ1 comprises lower clastic units overlain by a carbonate dominated marine succession that shows marked lateral and vertical facies changes. Sequence sets ϵ2 and ϵ3 together comprise a largely clastic dominated succession of marginal marine to non-marine sediments with subordinate shallow marine carbonates. Sequence set ϵ1 is richly fossiliferous at some levels with biostratigraphy established for trilobites, archaeocyaths, brachiopods, small shelly fossils, acritarchs and molluscs. The Emu Bay Shale Lagerstätte (Cambrian Series 2) from the north coast of Kangaroo Island occurs within a clastic-rich shelf succession dominated by conglomerate and sandstone. The fossil content is dominated by trilobites in terms of relative abundance and currently over 50 taxa are known including, Anomalocaris, the bivalved arthropods 'Isoxys' and 'Tuzoia', the nektaspids 'Emucaris' and 'Kangacaris', the megacheiran 'Oestokerkus' amongst a variety of other arthropods. Other common taxa include palaeoscolecid worms, 'Myoscolex', sponges, hyoliths, brachiopods, a vetulicolian and several other enigmatic forms. The oldest known well preserved complex arthropod eyes occur in this biota.

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 among others. The Memoir series is designed for longer monographic treatments, but will also consider thematic sets of papers and commonly publishes conference proceedings.

Cambrian Series 2 shelly fossils from thick carbonate successions in East Antarctica have received limited systematic treatment through the 20th century. Described here are the East Antarctic camenellan tommotiids from the Shackleton Limestone in the Central Transantarctic Mountains and the Schneider Hills limestone in the Argentina Range. This material comes from both newly sampled collections and incompletely described material from older collections. The assemblage supports correlation to the Dailyatia odyssei Zone and Pararaia janeae Trilobite Zone of South Australia, with the newly examined specimens of Dailyatia decobruta from the Shackleton Limestone providing direct correlation to the Mernmerna Formation of the Ikara-Flinders Ranges and White Point Conglomerate of Kangaroo Island. These East Antarctic assemblages include five species referred to Dailyatia, in addition to an undetermined kennardiid species and fragments of the problematic Shetlandia multiplicata. The results further corroborate the notion that fossiliferous carbonate clasts found on King George Island were sourced from the same carbonate shelf as the Shackleton Limestone, with the taxon S. multiplicata found in both units. The Schneider Hills limestone in the Argentina Range has yielded sclerites of Dailyatia icari sp. nov., currently only known from this location.

The purpose of this comment is to question the organic nature of the material described by Retallack (2011) as 'problematic megafossils' from the Moodlatana and Balcoracana Formations, Lake Frome Group of the Flinders Ranges, South Australia. By way of introduction, we note that there is a considerable history of structures described from sedimentary rocks as fossils that do not stand up to scrutiny (Hofmann 1971, 1992, 2005). The literature is replete with what Hofmann (1992) regarded as dubiofossils. The onus should always be on the author to demonstrate biological origins. Retallack (2011, p.1223) in discussing the need to name problematic fossils states that 'Vendobionta were informally noted by Mawson (1938, p. 259) as 'fossil impressions resembling brachiopod or bivalve form', but formal description of five species by Sprigg (1947) was needed before their global distribution and importance as Ediacaran fossils could be appreciated (Fedonkin et al. 2007).' This is misleading because Mawson's complete sentence is 'Fossil impressions resembling brachiopod or bivalve form, but probably merely impressions of clay galls'. Mawson was in fact describing a section through what would now be termed the Ediacaran Rawnsley Quartzite, from about 1.6 km north of Parachilna Creek and about 50 km to the south east of where Sprigg (1947) initially found the Ediacara biota near Ediacara in the Rawnsley Quartzite.

The most successful chronostratigraphic correlation methods enlist multiple proxies such as biostratigraphy and chemostratigraphy to constrain the timing of globally important bio- and geo-events. Here we present the first regional, high-resolution shelly fossil biostratigraphy integrated with δ¹³C chemostratigraphy (and corresponding δ¹⁸O data) from the traditional lower Cambrian (Terreneuvian and provisional Cambrian Series 2) of South Australia. The global ZHUCE, SHICE, positive excursions II and III and the CARE are captured in lower Cambrian successions from the Arrowie and Stansbury basins. The South Australian shelly fossil biostratigraphy has a consistent relationship with the δ¹³C results, bolstering interpretation, identification and correlation of the excursions. Positive excursion II straddles the boundary between the Kulparina rostrata and Micrina etheridgei zones, and the CARE straddles the boundary between the M. etheridgei and Dailyatia odyssei zones, peaking in the lower parts of the latter zone. New CA-TIMS zircon dates from the upper Hawker Group and Billy Creek Formation provide geochronologic calibration points for the upper D. odyssei Zone and corresponding chemostratigraphic curve, embedding the lower Cambrian successions from South Australia into a global chronostratigraphic context. This multi-proxy investigation demonstrates the power of integrated methods for developing regional biostratigraphic schemes and facilitating robust global correlation of lower Cambrian successions from South Australia (part of East Gondwana) with coeval terranes on other Cambrian palaeocontinents, including South and North China, Siberia, Laurentia, Avalonia and West Gondwana.

An early Cambrian shelly faunule from the Koolywurtie Limestone Member (Parara Limestone) at Teppers Knoll on Yorke Peninsula, South Australia, includes lingulate brachiopods, a variety of small shelly fossils such as tommotiids, hyolithelminth tubes and orthothecides, chancelloriid sclerites, sponge spicules, in addition to the oldest known occurrence of the redlichioid trilobite Xela. Correlation using faunas from other South Australian successions suggests that the member, in addition to the archaeocyathan fauna referred to as the 'Syringocnema favus beds', are early Botoman (pre-Pararaia janeae Zone) in age.

Predation is arguably one of the main driving forces of early metazoan evolution, yet the fossil record of predation during the Ediacaran-Early Cambrian transition is relatively poor. Here, we present direct evidence of failed durophagous (shell-breaking) predation and subsequent shell repair in the Early Cambrian (Botoman) epibenthic mollusc Marocella from the Mernmerna Formation and Oraparinna Shale in the Flinders Ranges, South Australia. This record pushes back the first appearance of durophagy on molluscs by approximately 40Myr.

The tannuolinid 'Micrina' belongs to the tommotiids - a common and widely distributed, but poorly understood, group of Early Cambrian fossil metazoans with multiple external organophosphatic sclerites. Recent findings of sessile articulated tommotiid scleritomes indicate that previous reconstructions of tommotiids as slug-like bilaterians with a dorsal cover of sclerites require detailed re-evaluation. Comparative ultrastructural work has already indicated that the tommotiids might be a sister group to the Brachiopoda, with 'Micrina' representing the most derived and brachiopod-like bimembrate tommotiid. Here we further develop and strengthen this controversial phylogenetic model with a new reconstruction of 'Micrina', where the two types of sclerites - mitral and sellate - belong to a near bilaterally symmetrical bivalved sessile organism. This new scleritome configuration was tested by recreating an articulated bivalved 'Micrina' from isolated mitral and sellate sclerites. The mitral and sellate sclerites of 'Micrina' are considered to be homologous with the ventral and dorsal valves, respectively, of organophosphatic linguliform brachiopods, indicating that a simple type of filter-feeding within an enclosed bivalved shell had started to evolve in derived tannuolinids. The new reconstruction also indicates that the phylogenetic range of 'bivalved', sessile lophophorates is larger than previously suspected.

The camenellan tommotiid Dailyatia is one of the most common fossils in shallow water carbonates from Cambrian Stages 2-4 in South Australia (Arrowie and Stansbury basins). Six species of Dailyatia are documented and new terminology for describing camenellan sclerites is introduced. Dailyatia sclerites are found in three fundamental sclerite types (A-C), each of which may be present in one to three sub-types depending on species. The previously described species Dailyatia ajax Bischoff 1976 and D. macroptera (Tate 1892) are revised and four additional species are described for the first time from South Australia. These include D. odyssei Evans & Rowell 1990, previously known only from Antarctica, and two new species; D. bacata sp. nov. and D. helica sp. nov. as well as a species left under open nomenclature. Two of the recognised species (D. macroptera and D. helica) occur in two different ecophenotypic variants. Species and variants are defined by differences in sclerite types present in the scleritome, sclerite morphology and ornament. The sclerites of Dailyatia are finely laminated with distal expansion of laminae supporting the prominent concentric ribs. The external surface is covered by a fine reticulate network which indicates that the sclerites were at least partly embedded in soft integument. The pattern of incremental growth reveals specific initial and possible gerontic growth stages with unique surface sculptures. Evidence of physical damage and growth disturbances is common in Dailyatia sclerites and many specimens reveal preferential abrasion of the apex. Apical canals are present in all sclerites and are connected to specialised internal apical structures. The internal surface of the sclerites in most species reveals raised platforms and depressed, scar like areas forming unique patterns in each sclerite type, presumably representing muscular attachment. Two specimens revealing ontogenetic fusion of Dailyatia sclerites have been recovered. Based on all available evidence, a new reconstruction of the Dailyatia scleritome is proposed. In the reconstruction, a central row of A and paired B sclerites is flanked on both sides by one or two lateral rows of C sclerites. The exact number of sclerites may vary between species. This reconstruction is based on an assumed slug-like bodyplan and the Dailyatia animal is considered to be a vagrant, benthic animal living in and around archaeocyathan-microbial buildups and in other shallow water carbonate environments.

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.

Rare specimens of eldonioids recovered from the lower Cambrian (Series 2, Stage 4) Emu Bay Shale (EBS) Konservat-Lagerstätte represent the first record of the group for the Cambrian of East Gondwana. The disc-shaped body of the EBS taxon bears fine concentric corrugations on the dorsal surface and, ventrally, a series of internal lobes that have primary and secondary bifurcations, as well as a coiled sac. It appears to be most similar to Rotadiscus and Pararotadiscus of the Cambrian Chengjiang and Kaili biotas of South China, respectively. While the structure of the internal lobes would indicate that this occurrence in the EBS represents a new taxon within the Rotadiscidae, lack of detail regarding the precise number of internal lobes and the condition of the circumoral tentacles warrants a more conservative approach in leaving the genus and species under open nomenclature. The EBS specimens also host trace fossils, including the remains of a burrow, which are generally lacking in the body-fossil-bearing layers of the Konservat-Lagerstätte interval. These traces appear to have been made by small organisms and are similar to traces associated with the discs of Pararotadiscus guizhouensis (Zhao and Zhu, 1994) from the Kaili Biota. The available taphonomic, paleoenvironmental, and ichnological evidence indicates that the EBS eldonioids are most likely vagrants that were transported or settled into the 'preservational trap' and subsequently exposed on the substrate for a brief period before burial, thereby allowing organisms to exploit their carcasses for nutrients or other purposes.

The effects of sedimentological, depositional and taphonomic processes on preservation potential of Cambrian small shelly fossils (SSF) have important implications for their utility in biostratigraphy and high-resolution correlation. To investigate the effects of these processes on fossil occurrence, detailed microfacies analysis, biostratigraphic data, and multivariate analyses are integrated from an exemplar stratigraphic section intersecting a suite of lower Cambrian carbonate palaeoenvironments in the northern Flinders Ranges, South Australia. The succession deepens upsection, across a low-gradient shallow-marine shelf. Six depositional Facies Sequences are identified ranging from protected (FS1) and open (FS2) shelf/lagoonal systems, high-energy inner ramp shoal complex (FS3), mid-shelf (FS4), mid- to outer-shelf (FS5) and outer-shelf (FS6) environments. Non-metric multi-dimensional scaling ordination and two-way cluster analysis reveal an underlying bathymetric gradient as the main control on the distribution of SSFs. Unlike groups that produced primary organophosphatic biominerals, taxa that built calcareous skeletons are more taphonomically-controlled, which is further exacerbated by sampling and processing biases. A strong facies association with condensed and reworked horizons suggests the stratigraphic occurrence of calcareous groups reflects conditions conducive to preservation (phosphogenesis and phosphatization) rather than true stratigraphic ranges. Consequently, organophosphatic taxa should take precedence in the erection of biostratigraphic zones for subdivision of lower Cambrian successions.

A new faunal assemblage is reported from the Tempe Formation (Cambrian Series 2, Stage 4; Ordian) retrieved from the Hermannsburg 41 drillcore, Amadeus Basin, central Australia. Two trilobite taxa, including one new species 'Gunnia fava' sp. nov., four brachiopod taxa, including the age-diagnostic 'Karathele napuru' (Kruse), 'Kostjubella djagoran' (Kruse) and 'Micromitra nerranubawu' Kruse, together with a bradoriid, helcionellids, hyoliths, echinoderms, chancelloriids, sponges and problematic tubes are described. The fauna has close links to those of the neighbouring Daly, Georgina and Wiso basins and suggests that the Tempe Formation correlates with the Australian Ordian stage (either the 'Redlichia forresti' or 'Xystridura negrina' assemblage zones). The Giles Creek Dolostone in the eastern Amadeus Basin, previously regarded as coeval with the Tempe Formation, has recently been reported to be of early Templetonian age in its type section. The described taxa from the Tempe Formation confirm that these two sedimentary units are not contemporaneous and that regional stratigraphic schemes should be amended.

The first mickwitziid brachiopod, 'Mickwitzia' sp., from East Gondwana is described from the lower Cambrian Ajax Limestone, Mt Scott Range in South Australia. The shells are fragmentary, but preserve sufficient details of morphology and micro-structure to allow positive identification to genus. The morphology of the dorsal valve apex and the extended cones on the internal surface indicate a close affinity with 'Mickwitzia muralensis' Walcott, 1913 from the early Cambrian of British Columbia, but scarcity of material precludes detailed comparison. This find extends the known range of the pivotal stem group brachiopod 'Mickwitzia' to East Gondwana.

A lack of well resolved biostratigraphic data has prevented robust regional and global correlation of lower Cambrian successions from South Australia. A new early Cambrian biostratigraphy, based on data derived from 21 measured stratigraphic sections and drill cores (11 described herein) reveals the abundance and diversity of shelly fauna from the Arrowie Basin, and the value of early Cambrian "small shelly fossils" (SSF) for biostratigraphic studies. Here we examine shelly fauna associated with the youngest of three recently established biozones, the Dailyatia odyssei Taxon Range Zone (hereafter D. odyssei Zone), and their correlative potential. The D. odyssei Zone features a diverse suite of tommotiids, organophosphatic brachiopods, bradoriid arthropods, molluscs and phosphatic problematica. This fauna permits strong correlation (often at species-level) with other major early Cambrian terranes, particularly Antarctica, South China and Laurentia, and suggest a Cambrian Series 2, Stages 3-4 age for the D. odyssei Zone. Bradoriids have proven to be useful biostratigraphic tools. Four new species and three new genera are described herein: Acutobalteus sinuosus gen. et sp. nov., Eozhexiella adnyamathanha gen. et sp. nov., Manawarra jonesi gen. et sp. nov. and Mongolitubulus descensus sp. nov. The description of Eohadrotreta sp. cf. zhenbaensis represents the first occurrence of the acrotretoid brachiopod Eohadrotreta from Australia.

A small assemblage of linguliformean brachiopods (nine taxa) is documented from the Giles Creek Dolostone (Cambrian Series 3, Stage 5; Templetonian) in the Ross River Gorge area, NE Amadeus Basin, central Australia. Taxa described include: 'Aksarinaia subtilicrusta' Percival and Kruse 2014, 'Aphelotreta' cf. 'minuta' Rowell 1980, 'Eothele granulata' Roberts in Roberts and Jell 1990, 'Hadrotreta' sp., 'Micromitra nerranubawu' Kruse 1990, 'Prototreta millsi' Brock and Percival 2006, 'Westonia' cf. 'nyapungensis' Kruse 1990, as well as two species left under open nomenclature: Linguloidea gen. et sp. indet. and Acrotheloidea gen. et sp. indet. The Giles Creek Dolostone fauna has strong similarities to those described from the Koonenberry Belt (far western New South Wales), and the Gum Ridge Formation from the neighboring Georgina Basin (Northern Territory and Queensland). These comparable linguliformean brachiopod faunas are all considered to be of Ordian to early Templetonian age (Cambrian Series 2, Stage 4-Series 3, Stage 5), which agrees with the early Templetonian (Cambrian Series 3, Stage 5) age assessment for the Giles Creek Dolostone based on co-occurring trilobite fauna. The absence of typical Ordian brachiopods 'Schizopholis napuru' (='Karathele napuru') (Kruse 1990) and 'Kostjubella djagoran' (='Vandalotreta djagoran') (Kruse 1990) suggests that these taxa may have shorter ranges and, therefore, would be useful for stage subdivision.