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Resumen: En este trabajo se analiza la morfología de Phyllozoon hanseni Jenkins y Gehling, un organismo fósil con forma de fronde y de simetría deslizada del Ediacárico de la Sierra de Flinders, Australia del Sur. El estudio se centra en la medición de los parámetros básicos de estos fósiles con la intención de identificar tendencias que sean diagnósticas para P. hanseni, ayudar a definir su morfología funcional, y reconciliar esta información con el contexto paleobiológico. Los principales hallazgos han sido que el tamaño de los ejemplares presenta una distribución no-normal y de sesgo negativo, y que los extremos de P. hanseni son muy distintos. Uno lo denominamos ‘cuchara’, y es redondeado, con unidades anchas dispuestas en ángulo agudo respecto al eje sagital. Dicho ángulo es mayor hacia el ápice y le confiere a éste un aspecto de pimpollo de rosa. La primera unidad consistentemente está en el lado izquierdo del epirelieve positivo. El otro extremo, el ‘cuchillo’, tiene un característico descenso lineal de anchura y longitud de sus unidades, que se mantienen perpendicular al eje del organismo. El área central, entre estas dos secciones, presenta bordes subparalelos, y lo denominamos ‘tronco’. Se ha detectado una fuerte correlación positiva entre la Longitud Mínima del Ejemplar y el Número Mínimo de Unidades, así como una moderada correlación positiva entre anchura y longitud de las unidades en la región central. Adicionalmente, los resultados sugieren un patrón de crecimiento asimétrico entre el incremento de tamaño y el número total de unidades desde el ápice del ‘cuchillo’. La morfología observada en P. hanseni se interpreta como un indicio de hábito bentónico postrado. Abstract: We have investigated the morphology of Phyllozoon hanseni Jenkins and Gehling, a frond-like fossil organism with glide reflection symmetry from the Ediacaran of the Flinders Ranges, South Australia. The focus of this study was to measure some basic physical parameters of these fossils to identify some distinguishing trends, to help build a picture of the functional morphology of P. hanseni, and then to reconcile this information in a palaeobiological context. The main findings are that specimen length displayed a non-normal, negatively skewed distribution, and that P. hanseni possesses two distinct ends. One dubbed here the ‘spoon’, is rounded in profile, with steep-angled positioning of thicker units and a rosebud-like appearance at the terminus, found to always begin on the left bank of the positive hyporelief. The other end, the ‘knife’, displays instead a gradual decrease in both unit width and length with positioning of units perpendicular to the body axis. The area between these two sections, with sub-parallel edges, is referred to as the ‘trunk’. Specimen length was found to be positively associated with both unit number and specimen width. Additionally, the findings suggest a longitudinally asymmetrical growth pattern of increasing size and number of units, with serial addition of units at the knife terminus. The observed morphology of P. hanseni suggests a lifestyle as a benthic, prostrate organism.

Comunicaciones presentadas en la LXXI Sesión Científica / Geoparque Montañas do Courel (Lugo), 26 de noviembre de 2021, [EN] A third specimen of Megistaspis (Ekeraspis) cf. hammondi is described from the most important Ordovician Burgess Shale-type Fossil-Lagerstätte in Morocco. The trilobite specimens with soft-part preservation are located in late Tremadocian levels within the Fezouata Formation, but are very rare. The studied specimen preserves the right antenna, and nine appendages under the right side of the exoskeleton, only evident when a break in the rock released part of the exoskeleton and revealed the underlying biramous appendages. These mostly consist of endopods, but also at least a couple of exopods, recognizable by their long lamellae. The first endopod seems to correspond to the distal tip of the third cephalic appendage, while the rest are thoracic appendages. The features of the preserved antenna indicate that most such appendages in other specimens from the same area are created or enhanced during preparation. Besides the studied asaphid, soft-part preservation of digestive tract and appendages are known from four coeval species, totalling about fifty published specimens. But it is quite possible that, like in the present specimen, biramous appendages may be preserved under the carapace of other specimens with antennae., [ES] Se presenta el tercer ejemplar del trilobites asáfido Megistaspis (Ekeraspis) cf. hammondi con Conservación excepcional de apéndices, procedente del Fossil-Lagerstätte ordovícico de tipo Burgess Shale más importante del mundo, localizado en Marruecos. Los trilobites con apéndices o partes blandas se detectan en niveles del Tremadociense superior dentro de la Formación de Fezouata, pero son fósiles muy raros. El ejemplar estudiado conserva la antena derecha y nueve apéndices situados bajo el exoesqueleto, localizados en la parte derecha del cuerpo. Se trata principalmente de endópodos, pero al menos en dos apéndices se reconocen partes de los exópodos porque conservan sus largas lamelas. El primer endópodo parece corresponder al extremo distal del tercer apéndice cefálico, y el resto son apéndices torácicos. Las antenas observadas en ejemplares comerciales de la misma especie suelen estar manipuladas por los preparadores y son poco fiables. Además del asáfido estudiado, la conservación de partes blandas y apéndices se conoce en otras cuatro especies coetáneas, totalizando medio centenar de ejemplares publicados. Pero es muy posible que existan muchos más casos en los que los apéndices de aquellos ejemplares que conserven las antenas permanezcan en realidad ocultos bajo el caparazón dorsal., El presente trabajo es una contribución a los proyectos CGL2017-87631-P del MICINN y 735 del PICG (IUGS-UNESCO), habiendo recibido financiación en especie de la empresa Jurassic Dreams (Alicante). AAS es beneficiario de fondos de investigación portugueses de la FCT – Fundação para a Ciência e Tecnologia, I.P. (ref. UIDB/00073/2020), en el ámbito de la Unidad de I&D Centro de Geociências (CGEO).

The trilobite Redlichia Cossmann, 1902 is an abundant element of the lower Cambrian (Series 2, Stage 4) Emu Bay Shale (EBS) Konservat-Lagerstätte on Kangaroo Island, South Australia. Well-preserved, fully articulated specimens from this deposit are known to reach lengths of up to 25 cm, representing one of the largest known Cambrian trilobites. Until now, all Redlichia specimens from the EBS have been referred to Redlichia takooensis Lu, 1950, a species originally described from South China. Previous work recognized considerable differences in exoskeletal morphology among specimens of varying sizes, which was attributed to ontogeny. However, close examination of a large collection of recently acquired specimens shows that this variation actually represents two distinct morphs, interpreted here as separate species: R. takooensis, and a large, new species, Redlichia rex sp. nov. An analysis of morphological variation in holaspides (‘adults’) of the more common R. takooensis reveals considerable ontogenetic change occurred even during this later phase of growth. Some specimens of both Redlichia species from the EBS also exhibit exceptionally preserved soft-part anatomy, particularly the antennae and biramous appendages. Here, appendages (antenniform and biramous) and digestive structures are described, and biramous appendage reconstructions of R. rex sp. nov. are presented, which show a striking resemblance to some early Cambrian trilobites from South China. In particular, R. rex has a tripartite exopodite, as well as a dorsoventrally deep protopodite with gnathobasic spines used to shred or crush food items. Based on recent phylogenetic analyses, it is possible that an exopodite with tripartite subdivisions represents the plesiomorphic condition for Artiopoda (trilobites and kin). The digestive system of R. takooensis exhibits a series of paired digestive glands in the cephalon and anterior thorax, similar to those described for a number of other Cambrian and Ordovician trilobites. http://zoobank.org/urn:lsid:zoobank.org:pub:507BEAFC-4AFA-43F4-A5C4-49E4B58C658E

Trabajo presentado en el II Simposio Internacional de Paleontología del Perú, celebrado en Lima (Perú), del 27 al 30 de noviembre de 2018

International Conference on Trilobites and Their Relatives (6ª. 2017. Tallinn, Estonia), The goal of the conference is to present and discuss recent progress in studies on all aspects of trilobites and their relatives (e.g. morphology, evolution, phylogeny, ecology, geography). The pre- and post-conference field trips will examine trilobite-bearing rocks from the lower Cambrian to upper Silurian., Instituto Geológico y Minero de España, España

International Conference on Trilobites and Their Relatives (6ª. 2017. Tallinn, Estonia), The claimed report of the Scandinavian trilobite Symphysurus angustatus (Sars & Boeck in Boeck) in the Fezouata Shale (Lower Ordovician) of the Moroccan central Anti‐Atlas is reviewed here, and two distinctive Gondwanan species are recognized instead. The older one occurs in upper Tremadocian mudstones belonging to the Fezouata Fossil‐Lagerstätte. It is here described as Symphysurus ebbestadi n. sp., commonly occurring in monospecific groups of tens to hundreds of individuals and rarely preserving soft‐bodied features. A second species is from slightly higher beds and corresponds to Symphysurus sicardi (Bergeron). It is found isolated in nodules of slightly uncertain stratigraphical position, but near the Tremadocian–Floian boundary. Additionally, a third species left in open nomenclature (Symphysurus? n. sp.) comes from an unknown locality also in the Zagora area. The new Moroccan records of Symphysurus occur in a pilekiid‐bavarillid assemblage that has been attributed to a proximal biofacies of lower shoreface affinities, but typical shallower water trilobites as Taihungshania are lacking. The record of associated genera such as Platypeltoides also suggests relatively deeper environments, as in the Euloma Association of Bohemia, somewhat comparable with the nileid biofacies. The abundance of mesopelagic graptolites on the same beds, in some cases covering complete carapaces of Symphysurus, also indicates a deeper placement, well below storm wave base., Consejo Superior de Investigaciones Científicas, España, Instituto Geológico y Minero de España, España, University of Adelaide, Australia

Trabajo presentado en el 4th International Congress on Ichnology - ICHNIA 2016: Ichnology for the 21st century: (Palaeo) Biological Traces towards Sustainable Development, celebrado en Idanha-a-Nova (Portugal), del 6 al 9 de mayo de 2016, Middle Ordovician shales from the Valongo and Moncorvo formations recorded temporary dysoxic environments, inhabited by opportunistic faunas that also include highly specialized deposit feeders. Resulting ichnofossils include Phycodes noa Mikuláš, a horizontally-ramified burrow complex, so far only known from older beds in the Prague Basin, as well as a large spiral grazing trace close to Rotundusichnium zumayensis Gómez de Llarena, which is widely distributed in Alpine flysch deposits. Phycodes noa from the Valongo Formation occurs as quite large, horizontally flabellate structure with up to 10 diverging passages. Specimens from the Canelas quarry (Arouca) are commonly infilled by pellets (Tomaculum), and are preserved flattened and tectonically expanded. Giant Rotundusichnium-like forms are exclusive from the Canelas quarry and consist of ?concentric to tightly spiral traces with a large elliptical outline (major axis up to 130 cm long), showing endichnial ribbons inclined to the centre of the structure. These are associated with imploded fragmocones of nautiloids preserved under them, and the trace maker harvested the microbial proliferation around them in tight centrifugal coils. The third remarkable trace corresponds to bite marks preserved in large trilobite carapaces. They have a consistent acute V-shaped outline and represent marginal breakage, usually placed in the right pygidial pleural border of asaphids, in diverse margins of calymenaceans or in semi-infaunal molluscs. These triangular bite marks are attributed to large nautiloid predators or scavengers, sometimes attacking freshly-molted giant trilobites., This research is a contribution to the projects CGL2012-39471 of the Spanish MINECO and IGCP-591 (IUGS-UNESCO).

Trabajo presentado en el IGCP 591 Closing Meeting: A combined data-model approach to understand the Early to Middle Palaeozoic Revolution, celebrado en Ghent (Bélgica), del 6 al 9 de julio de 2016

Trabajo presentado en el IX Congreso Geológico de España, celebrado en Huelva (España), del 12 al 14 de septiembre de 2016, [ES] La nuevas divisiones de la escala global del Sistema Ordovícico, con excepción de los pisos Tremadociense e Hirnantiense, son difíciles de aplicar en la Península Ibérica, pues sus estratotipos de límite radican en facies y faunas de aguas profundas, desconocidas en las plataformas someras y de paleolatitud elevada del ámbito peri-gondwánico. Antes de ello, la escala regional británico-avalónica fue utilizada en Iberia durante todo el siglo XX, pero presenta serios inconvenientes de correlación vinculados con la propia evolución, conceptual y de criterio, registrada en las áreas tipo británicas durante los últimos 40 años. Sin embargo, la escala regional bohemo-ibérica es la que actualmente aporta una mayor precisión a las correlaciones, pues se basa en elementos bioestratigráficos y biocronológicos de distribución común a todo el margen peri-gondwánico europeo y norteafricano, y la que mantiene vínculos episódicos con otras escalas regionales, que permitirán resolver progresivamente las equivalencias con la escala global, [EN] The new divisions from the global scale for the Ordovician System, except for the Tremadocian and Hirnantian stages, are difficult to correlate in the Iberian Ordovician, because their GSSPs involve deep-water facies and faunas not recorded in the shallow, high-paleolatitudinal settings of the peri-Gondwanan area. Previously to the Global scale, the British-Avalonian regional scale had been widely adopted in the Iberian Ordovician during all the 20th Century, but there are serious correlation problems due to the former’s conceptual evolution and variable criteria used for the British type areas during the last 40 years. However, the use of the Bohemo-Iberian scale instead, provides better precision to Iberian correlations, because it is based in some local biostratigraphical and biochronological markers, widely recorded over an extensive area of the European and North African peri-Gondwanan margin. The Bohemo-Iberian scale shows episodic links with other regional scales, which will provide indirect correlations also with the global Ordovician scale., Este trabajo es una contribución al proyecto IBEROR (CGL2012-39471) del MINECO.

Trabajo presentado en el 60th Annual Meeting of the Palaeontological Association, celebrado en Lyon (Francia), del 14 al 17 de diciembre de 2016, We have revisited the stratotype area of the Lower Formation of the Second Bani Group, west of Tagounite in the Moroccan Anti-Atlas, and sampled brachiopods and trilobites from its uppermost quartzitic horizons. In addition to those brachiopods listed in previous papers on the region, we have found Plectothyrella sp. and Kinnella sp. Both genera are exclusive of the pandemic Hirnantia fauna, which allows confirmation of a Hirnantian age for the upper member of the Lower Second Bani Formation. By contrast, the lower member of the same unit has yielded Katian brachiopods and trilobites, such as Eostropheodonta intermedia, Destombesium sp., Hirnantia sp. (species other than H. sagittifera), Actinopeltis aff. insocialis, Mucronaspis termieri and Cekovia aff. perplexa. According to the lithostratigraphic framework, the Katian/Hirnantian boundary lies within the Lower Formation of the Second Bani Group and lithostratigraphically correlative horizons, such as those reported in Bou Ingarf. The latter were mainly dated as a result of lithostratigraphic and sequential correlations and, based on correlation with the Tagounite area, are in need of revision. The age of the lower part of the chitinozoan Tanuchinita elongata Biozone should be re-evaluated, and the suggested delayed onset of the Hirnantian glaciation reconsidered.

Trabajo presentado en el IX Congreso Geológico de España, celebrado en Huelva (España), del 12 al 14 de septiembre de 2016, [ES] Se presenta el caso de los peruanos Klaus Hönninger Mitrani y Carlos A. Vildoso Morales, considerados como paleontólogos de prestigio en los medios de comunicación de su país. Ambos lideran empresas de apariencia institucional, el llamado “Museo Paleontológico Meyer-Hönninger” y el “Instituto Peruano de Estudios en Paleovertebrados”, respectivamente. Las actividades de “investigación científica” del primero han sido prácticamente desactivadas por las autoridades del Ministerio de Cultura, tras exigirle permisos de prospección, y también por la denuncia pública de fraude en el I Simposio Internacional Paleontología del Perú (Lima, 2013). Sin embargo, las operaciones del segundo, quien esgrime una falsa titulación en Paleontología por la Universidad de La Plata (Argentina), han experimentado un incremento sustantivo, con contratos sobre patrimonio paleontológico suscritos con la organización del rally Dakar 2014 y compañías mineras, hasta el punto de que C.A. Vildoso ostenta actualmente el cargo de presidente del comité organizador del IX Congreso Latinoamericano de Paleontología., [EN] The case of Klaus Hönninger Mitrani and Carlos A. Vildoso Morales from Peru, considered prestigious palaeontologists by the media in their country is discussed here. They both lead official-looking businesses, the “Meyer-Hönninger Palaeontological Museum” and the “Peruvian Institute of Palaeovertebrate Studies”, respectively. The “scientific research” activities of the former have been basically desactivated by authorities of the Ministry of Culture, after requiring it to obtain prospection permits, and after a public complaint for fraud in the First International Simposium of Palaeontology of Peru (Lima, 2013). However, the dealings of the latter, who claims to have a title on Palaeontology from the University of La Plata (Argentina), which is fake, has experienced a considerable increase, with palaeontological heritage contracts with the organization of the 2014 Dakar Rally and mining companies. The prominence of the position he has attained is such that he is the President of the Organising Committee of the IX Latinamerican Palaeontological Congress.

La nuevas divisiones de la escala global del Sistema Ordovícico, con excepción de los pisos Tremadociense e Hirnantiense, son difíciles de aplicar en la Península Ibérica, pues sus estratotipos de límite radican en facies y faunas de aguas profundas, desconocidas en las plataformas someras y de paleolatitud elevada del ámbito peri-gondwánico. Antes de ello, la escala regional británico-avalónica fue utilizada en Iberia durante todo el siglo XX, pero presenta serios inconvenientes de correlación vinculados con la propia evolución, conceptual y de criterio, registrada en las áreas tipo británicas durante los últimos 40 años. Sin embargo, la escala regional bohemo-ibérica es la que actualmente aporta una mayor precisión a las correlaciones, pues se basa en elementos bioestratigráficos y biocronológicos de distribución común a todo el margen peri-gondwánico europeo y norteafricano, y la que mantiene vínculos episódicos con otras escalas regionales, que permitirán resolver progresivamente las equivalencias con la escala global.

Comunicación presentada en STRATI 2015, 2 International Congress on Stratigraphy, 19. - 23. July 2015, Graz, Austria

Comunicación presentada en STRATI 2015, 2 International Congress on Stratigraphy, 19. - 23. July 2015, Graz, Austria

The first Furongian trilobites are described herein from the Cambrian of the Cantabrian Zone, NW Spain. They were collected during the construction of the >Túnel Ordovícico del Fabar> from the shales of >El Fabar Beds> in the La Matosa member of the Barrios Formation. The assemblage includes the aphelaspidine genus Maladioidella, with a specimen identified as M. cf. colcheni, a species previously known from Sierra de la Demanda (Spain), and possibly Sardinia and Oman. Fragments of an indeterminate olenid trilobite and phyllocarid crustaceans have also been recorded. Based on the acritarch assemblage, these beds are considered as late Jiangshanian or earliest Stage 10 of the Cambrian System. The ichnofossil Cruziana semiplicata has also been collected in the tunnel from the upper part of the Ligüeria Member (Tremadocian) of the Barrios Formation, clearly postdating the occurrence of Maladioidella colcheni, its supposed tracemarker according to some authors. The separate record of both taxa (a Furongian trilobite and a Cambro-Ordovic-ian trace fossil) does not support this statement, so their relationship would be refuted in this case.

Illaenid trilobites were relatively scarce in south-polar peri-Gondwanan areas during the Ordovician, with all their African occurrences restricted to the Middle and Upper Ordovician of Morocco. At a specific level, only the Bohemian form Ectillaenus benignensis (Novák) has been positively identified from the Middle Ordovician of that region. In the present work we add the discovery of the new form Caudillaenus nicolasi gen. et sp. nov., occurring in a single bed of late Darriwilian 2 age within the Taddrist Formation of the Rahiat region (south of Alnif), in the central Moroccan Anti-Atlas. The new genus is characterized by a large and subtriangular pygidium, a cephalon with relatively large eyes, a broad rostral plate with a short upwardly and forwardly turned posterior flange, and a globose hypostome. It shows a spheroidal enrolment type previously unknown in illaenids, with the pygidium protruding beyond the cephalon, and the cephalic margin fitting into a shallow and wide coaptative furrow on the pygidial doublure.

The Armorican Quartzite is one of the most characteristic units of the Paleozoic of SW Europe, being represented in the Lower Ordovician succession of Brittany and Normandy (western France), and also over most of the Hesperian and Iberian massifs of the Iberian Peninsula (in the clarified sense of San José, 2006), with the exception of the Ossa-Morena and South-Portuguese zones (Gutiérrez-Marco et al., 2002; Vera, 2004; Ribeiro, 2006). In Portugal and from north to south, the Armorican Quartzite facies is equivalent to the Marão Formation of Trás-os-Montes (Sá et al., 2005), the Santa Justa Formation of the Tabagón-Valongo-Tamames domain (Romano and Diggens, 1974), the Armorican Quartzite Formation of the Buçaco and Amêndoa-Mação areas (Young, 1988; Romão, 2000a) and the Serra do Brejo Formation in the Dornes area (Cooper, 1980). In spite of the generalized absence of biostratigraphical ties for correlation other than ichnofossils and a few chitinozoan or graptolite data, the latter generally coming from the overlying shales, the Armorican Quartzite in Portugal have been considered as involving a diachronism in sedimentation from Arenig to Llandeilo, becoming younger from west to east (Ribeiro, 1974) according to regional data from the Valongo to Trás-os-Montes areas. These data have been compiled in some syntheses (Hammann et al., 1982; Romano, 1982; Oliveira et al., 1992). However, the single paleontological argument in support of such diachronism, a Llandeilian trilobite found in the middle part of the Marão Formation at Moncorvo (Teixeira and Rebelo, 1976) was later reviewed by Gutiérrez- Marco et al. (1995), and Sá et al. (2003, 2009), who demonstrated that the supposed trilobite was in reality the trace fossil Rusophycus carleyi (James), also recorded in other Gondwanan areas within the Arenigian succession (Seilacher, 1970; Gibb et al., 2010). No other authors were able to demonstrate the claimed diachronism in the sedimentation of the Armorican Quartzite, whose deposit took place entirely in the Eremochitina brevis chitinozoan biozone (Paris, 1981, 1990; Paris et al., 1982, 2007), regarded as “early-mid Arenigian” or as late Floian according to the global scale (Paris et al., 2007; Videt et al., 2010). Romão et al. (2010) recently questioned the current age of the Armorican Quartzite in the southern Central Iberian Zone, and supported a local late Cambrian age for this formation in the Amêndoa- Carvoeiro synform based in a couple of ichnological data, a single U-Pb dating, and some highly speculative tectonostratigraphic inferences which in our opinion are far from being demonstrated. Also with reference to this area, Romão et al. (2010) envisaged the Armorican Quartzite as a highly diachronic late Cambrian to Early Ordovician unit for the Iberian Peninsula. This statement is refuted here with the presentation of new ichnologic evidence that supports the previous Early Ordovician dating of the Armorican Quartzite in the Amêndoa-Carvoeiro synform.

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p. 33-110 En este capítulo se tratan una serie de grupos que son típicamente bioconstructores o formadores de arrecifes. Aunque otros grupos de organismos de diversa afinidad biológica, tales como procariotas (bacterias, cianobac­terias), algas, braquiópodos, bivalvos, etc., pueden cons­truir o participar en la construcción de arrecifes, a lo lar­go de la historia geológica de la Tierra y en la actualidad, po­ríferos, cnidarios y afines han sido y son los más impor­tantes componentes de los depósitos arrecifales.

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 correspondingδ¹⁸O 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 theexcursions. Positive excursion II straddles the boundary between the Kulparina rostrata and Micrina etheridgeizones, 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. Refereed/Peer-reviewed

Ediacara fossil surfaces from the Flinders Ranges (South Australia) commonly record excellent preservation quality and can provide a palaeoecological window into some of the oldest communities on Earth (ca. 555 Ma). An excavated semi-contiguous sandstone bed of 6.5 m2 from a fossil locality at Crisp Gorge in the central Flinders Ranges records an abundance of taxa and structures characteristic of White Sea assemblage communities. Stratigraphic analysis places the fossil surface within the Oscillation Rippled Sandstone Facies of the Ediacara Member at Crisp Gorge. The community appears to be predominantly juvenile forms, with Dickinsonia costata, Parvancorina minchami and Tribrachidium heraldicum present only within interpreted juvenile size ranges. The textured organic surface contains structures including low relief ridges and round bosses, but overall records a smooth bed surface and is interpreted as representing a surface with only an immature microbial mat developed before burial. No effaced or decayed organisms were identified. Community analysis describes an intermediate Shannon diversity (1.27) and an uneven community dominated by the population of D. costata, which comprises more than 50% of the individuals. The examined parameters, when combined with the presence of small, juvenile taxa and an immature organic mat, suggests that the community inhabiting this surface prior to its catastrophic burial may have been comparable to a modern early-stage, primary successional community. The Crisp Gorge bed emphasizes that Ediacara fossil surfaces from South Australia span a range of developmental stages and offer a window into Ediacaran sea-floor communities at various stages of maturity. Refereed/Peer-reviewed

The Emu Bay Shale Lagerstätte (Cambrian Series 2, Stage 4) occurs on the north coast of Kangaroo Island, South Australia. Over 50 species are known from here, including trilobites and non-biomineralized arthropods, palaeoscolecids, a lobopodian, a polychaete, vetulicolians, nectocaridids, hyoliths, brachiopods, sponges and chancelloriids. A new chelicerate, Wisangocaris barbarahardyae gen. et sp. nov., is described herein, based on a collection of some 270 specimens. It is up to 60 mm long, with the length of the cephalic shield comprising about 30% that of the exoskeleton. The cephalic margin has three pairs of bilaterally-symmetrical small triangular spines. A pair of small eyes is placed well forwards on the ventral margin of the cephalic shield. The trunk comprises 11 segments that increase in length while narrowing posteriorly, each possibly bearing a pair of biramous appendages; the most posterior segment is almost square whereas the others are transversely elongated. The spatulate telson is proportionately longer than in taxa such as Sanctacaris, Utahcaris and Leanchoilia. Up to eight (?four pairs) of 3 mm-long elements bearing alternating inward-curving short and long spines beneath the cephalic shield are interpreted as basipodal gnathobases, part of a complex feeding apparatus. A well-developed gut includes a stomach within the cephalic shield; it extends to the base of the telson. In a few specimens there are shell fragments within the gut, including those of the trilobite Estaingia bilobata (the most common species in the biota); these fragments have sharp margins and extend across the gut lumen. The species may have been a predator or a scavenger, ingesting material already broken up by a larger predator/scavenger. The morphology of this taxon shares many overall body features with Sanctacaris, and some with Sidneyia, particularly its gnathobasic complex. These chelicerate affinities are corroborated by phylogenetic analyses. Refereed/Peer-reviewed

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-Lagerstatten. 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-Lagerstatten. Refereed/Peer-reviewed

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. Electronic supplementary material The online version of this article (doi:10.1186/s12862-014-0214-z) contains supplementary material, which is available to authorized users.