Abundant material from a new quarry excavated in the lower Cambrian Emu Bay Shale (Kangaroo Island, South Australia) and, particularly, the preservation of softbodied features previously unknown from this Burgess Shaletype locality, permit the revision of two bivalved arthropod taxa described in the late 1970s, 'Isoxys communis' and 'Tuzoia australis'. The collections have also produced fossils belonging to two new species: 'Isoxys glaessneri' and 'Tuzoia sp.' Among the soft parts preserved in these taxa are stalked eyes, digestive structures and cephalic and trunk appendages, rivalling in quality and quantity those described from better-known Lagerstätten, notably the lower Cambrian Chengjiang fauna of China and the middle Cambrian Burgess Shale of Canada.

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 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.

Recent fossil discoveries from the lower Cambrian Emu Bay Shale (EBS) on Kangaroo Island, South Australia, have provided critical insights into the tempo of the Cambrian explosion of animals, such as the origin and seemingly rapid evolution of arthropod compound eyes, as well as extending the geographical ranges of several groups to the East Gondwanan margin, supporting close faunal affinities with South China. The EBS also holds great potential for broadening knowledge on taphonomic pathways involved in the exceptional preservation of fossils in Cambrian Konservat-Lagerstätten. EBS fossils display a range of taphonomic modes for a variety of soft tissues, especially phosphatization and pyritization, in some cases recording a level of anatomical detail that is absent from most Cambrian Konservat-Lagerstätten.

The lower Cambrian Emu Bay Shale on Kangaroo Island, South Australia, contains the only known Cambrian Burgess Shale-type biota in Australia. Two new lamellipedian arthropods, 'Emucaris fava' gen. et sp. nov. and Kangacaris zhangi gen. et sp. nov., from the Emu Bay Shale Lagerstätte are described as monotypic genera that are resolved cladistically as a monophyletic group that is sister to Naraoiidae + Liwiidae and classified within the Nektaspida as a new family Emucarididae. Shared derived characters of Emucarididae involve a bipartite, elongate hypostome and elongation of the pygidium relative to the cephalic shield and very short thorax. A monophyletic Liwiidae is composed of 'Liwia' and the Ordovician 'Tariccoia' + 'Soomaspis' but excludes 'Buenaspis', and even the membership of 'Buenaspis' in Nektaspida is contradicted amongst the shortest cladograms. New morphological interpretations favour affinities of 'Kwanyinaspis' with Conciliterga rather than with Aglaspidida, and 'Phytophilaspis' with Petalopleura.

Background: Vetulicolians are one of the most problematic and controversial Cambrian fossil groups, having been considered as arthropods, chordates, kinorhynchs, or their own phylum. Mounting evidence suggests that vetulicolians are deuterostomes, but affinities to crown-group phyla are unresolved. Results: A new vetulicolian from the Emu Bay Shale Konservat-Lagerstätte, South Australia, 'Nesonektris aldridgei' gen. et sp. nov., preserves an axial, rod-like structure in the posterior body region that resembles a notochord in its morphology and taphonomy, with notable similarity to early decay stages of the notochord of extant cephalochordates and vertebrates. Some of its features are also consistent with other structures, such as a gut or a coelomic cavity. Conclusions: Phylogenetic analyses resolve a monophyletic Vetulicolia as sister-group to tunicates (Urochordata) within crown Chordata, and this holds even if they are scored as unknown for all notochord characters. The hypothesis that the free-swimming vetulicolians are the nearest relatives of tunicates suggests that a perpetual free-living life cycle was primitive for tunicates. Characters of the common ancestor of Vetulicolia + Tunicata include distinct anterior and posterior body regions - the former being non-fusiform and used for filter feeding and the latter originally segmented - plus a terminal mouth, absence of pharyngeal bars, the notochord restricted to the posterior body region, and the gut extending to the end of the tail.

Diverse interpretations of Ediacaran organisms arise not only from their enigmatic body plans, but also from confusion surrounding the sedimentary environments they inhabited and the processes responsible for their preservation. Excavation of Ediacaran bedding surfaces of the Rawnsley Quartzite in South Australia has provided the opportunity to study the community structure of the Ediacara biota, as well as the autecology of individual organisms. Analysis of two bedding surfaces preserving large numbers of Parvancorina illustrates that individuals display a preferred, unidirectional orientation aligned with current, as indicated by the identified current proxies: tool marks, overfolded edges of Dickinsonia, felled fronds and drag structures generated by uprooted frond holdfasts. Taphonomic and morphological evidence suggests that the preferred orientations of Parvancorina individuals are not the result of passive current alignment, but represent a rheotactic response at some stage during their life cycle. These results illustrate a previously unrecognized life mode for an Ediacaran organism and arguably the oldest known example of rheotaxis in the fossil record. The morphology and previously suggested phylogenetic affinities of Parvancorina are also re-evaluated. Apart from possessing a bilaterally symmetrical body, there are no unequivocal morphological characters to support placement of Parvancorina within the Euarthropoda or even the Bilateria.