Cambrian rocks in South Australia occur in the Stansbury, Arrowie, eastern Officer and Warburton Basins. The succession in the Stansbury and Arrowie Basins can be divided into three sequence sets (supersequences), C1, C2 and C3. Sequence set C1 can be divided into five third-order sequences: C1.0, C1.1A, C1.1B, C1.2 and C1.3. Trilobites from the Stansbury and Arrowie Basins are restricted largely to the lower part of the succession. Four trilobite zones are recognized: 'Abadiella huoi' (latest Atdabanian–earliest Botoman), 'Pararaia tatei', 'Pararaia bunyerooensis' and 'Pararaia janeae' Zones (all Botoman). Trilobites higher in the succession are known from only a few horizons and in part correlate with the upper Lower Cambrian Lungwangmiaoan Stage of China, equivalent to the top Toyonian. 'Pagetia sp.' has been reported in the Coobowie Formation of the Stansbury Basin, thus suggesting an early Middle Cambrian age. The Cambrian faunas of the Warburton Basin range in age from early Middle Cambrian (Late Templetonian) to very Late Cambrian, although the richest faunal assemblages are late Middle Cambrian ('Ptychagnostus punctuosus to Goniagnostus nathorsti' Zones). Conodonts, including 'Cordylodus proavus', occur in a Datsonian fauna. The Arrowie Basin contains the most complete and best studied archaeocyath succession in the Australia–Antarctica region. The 'Warriootacyathus wilkawillensis', 'Spirillicyathus tenuis' and 'Jugalicyathus tardus' Zones from the lower Wilkawillina Limestone (Arrowie Basin) and equivalents are correlated with the Atdabanian. Botoman archaeocyathids occur higher in the Wilkawillina Limestone. The youngest (Toyonian) archaeocyath fauna in Australia occurs in the Wirrealpa Limestone (Arrowie Basin). Brachiopods and molluscs of the Arrowie and Stansbury Basins can be divided into four biostratigraphic assemblages. Several informal Early Cambrian SSF biostratigraphic assemblages are recognized. Probable tabulate-like corals occur in the Botoman Moorowie Formation. Seven informal acritarch assemblages occur in the Early Cambrian of the Stansbury and Arrowie Basins. Trace fossils may mark the Precambrian–Cambrian boundary. Only two of several tuffaceous horizons from the Stansbury and Arrowie Basins have been dated (i) a date of 522.0 ± 2.1 Ma from the Heatherdale Shale of the Stansbury Basin, about 400m above latest Atdabanian archaeocyathids and (ii) a date of 522.0 ± 1.8 Ma from the lower part of the Billy Creek Formation in the Arrowie Basin. Neither date is regarded as reliable.

An assemblage of bradoriid arthropods from the Mernmerna Formation in the Donkey Bore Syncline, central Flinders Ranges, South Australia contains eleven species, including three species of the enigmatic ornamented spine 'Mongolitubulus'. Four new taxa are described, 'Onagrocharion tuberosus' gen. et sp. nov., 'Amphikeropsis myklosis' gen. et sp. nov., 'Hipponicharion australis' sp. nov. and 'Mongolitubulus unispinosa' sp. nov. The presence of 'Hipponicharion australis' sp. nov. in the upper Mernmerna Formation represents the first occurence of the genus in Australia and extends the biogeographic range of Hipponicharion to eastern Gondwana. Bradoriid specimens of 'Mongolitubulus unispinosa' sp. nov. exhibiting a single mature ornamented spine attached to the central portion of the carapace provides definitive evidence of a bradoriid affinity for the enigmatic, widespread 'Mongolitubulus' small shelly fossil taxon. The assemblage includes several species that facilitate correlation with the Stansbury Basin of South Australia, but also with faunas from other Cambrian palaeocontinents, including Antarctica and Laurentia.

Phosphatized articulated palaeoscolecid scleritome fragments with attached 'Hadimopanella' Gedik, 1977 plates are described from the lower Cambrian Mernmerna Formation of South Australia. 'Hadimopanella' is principally known from single, isolated, button-shaped, phosphatic sclerites. The new articulated material from South Australia reveals for the first time the configuration of plates referable to Hadimopanella within the scleritome. The scleritome fragments represent the main trunk sections of the cuticle with anterior and posterior terminations lacking. Each annulus on the trunk is ornamented by rows of irregularly alternating 'Hadimopanella' plates. The large majority of plates display a single, centrally located, conical node referable to the form species 'H. apicata' Wrona, 1982. However, individual plates display considerable morphological variation with plates situated along the flattened trunk margin identical to the form species 'H. antarctica' Wrona, 1987. The South Australian material displays the detailed scleritome configuration of cuticular plates and platelets and demonstrates irrefutably that plates of the form species 'H. apicata' and 'H. antarctica' occur as mineralized cuticular elements on the same palaeoscolecid scleritome.

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.

Early Cambrian tommotiids are problematic fossil metazoans with external organophosphatic sclerites that have been considered to be basal members of the lophophorate stem group. Tommotiids are almost exclusively known from isolated or rarely fused individual sclerites, which made previous reconstructions of the actual organism highly conjectural. However, the recent discovery of the first articulated specimens of the tommotiid 'Eccentrotheca' revealed a tubular sclerite arrangement (scleritome) that limited the possible life habit to sessile filter feeding and thus further supported a lophophorate affinity. Here, we report the first articulated specimens of a second tommotiid taxon, 'Paterimitra' from the Early Cambrian of the Arrowie Basin, South Australia. Articulated specimens of 'Paterimitra' are composed of two bilaterally symmetrical sclerite types and an unresolved number of small, asymmetrical and irregular crescent-shaped sclerites that attached to the anterior margin of the symmetrical sclerites. Together, the sclerites form an open cone in which the symmetrical sclerites are joined together and form a small posterior opening near the base of the scleritome, while the irregular crescent-shaped sclerites defined a broad anterior opening. The coniform scleritome of 'Paterimitra' is interpreted to have attached to hard substrates via a pedicle that emerged through the small posterior opening (sometimes forming a tube) and was probably a sessile filter feeder. The scleritome of 'Paterimitra' can be derived from the tubular scleritome of 'Eccentrotheca' by modification of basal sclerites and reduction in tube height, and probably represents a more derived member of the brachiopod stem group with the paired symmetrical sclerites possibly homologous to brachiopod valves.

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.

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.

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.

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.

A diverse, well preserved fossil assemblage consisting of micro- and macro-sized molluscs, sponge spicules, chancelloriid sclerites, hyolithelminth tubes, tommotiids, protoconodonts and lobopodian sclerites from the Third Plain Creek Member (Pararaia bunyerooensis Zone) of the Mernmerna Formation in the eastern Flinders Ranges, Arrowie Basin, South Australia is described. Molluscs are represented by hyoliths, helcionellids and a single bivalve species. The enigmatic helcionellid taxon Marocella mira is formally described for the first time from the Arrowie Basin and forms the basis of a new helcionellid family, the Marocellidae. Sclerites of the lobopodian Microdictyon jinshaense Zhang and Aldridge are described for the first time outside South China. Whilst many of the taxa are biostratigraphically long ranging, several species in the assemblage facilitate correlation across the Arrowie Basin, with the neighbouring Stansbury Basin to the south, and also with faunas from other Cambrian palaeocontinents, including Antarctica, South China and Laurentia.