A cryptic record of Burgess Shale‐type diversity from the early Cambrian of Baltica

Exceptionally preserved ‘Burgess Shale‐type’ fossil assemblages from the Cambrian of Laurentia, South China and Australia record a diverse array of non‐biomineralizing organisms. During this time, the palaeocontinent Baltica was geographically isolated from these regions, and is conspicuously lacking in terms of comparable accessible early Cambrian Lagerstätten. Here we report a diverse assemblage of small carbonaceous fossils (SCFs) from the early Cambrian (Stage 4) File Haidar Formation of southeast Sweden and surrounding areas of the Baltoscandian Basin, including exceptionally preserved remains of Burgess Shale‐type metazoans and other organisms. Recovered SCFs include taxonomically resolvable ecdysozoan elements (priapulid and palaeoscolecid worms), lophotrochozoan elements (annelid chaetae and wiwaxiid sclerites), as well as ‘protoconodonts’, denticulate feeding structures, and a background of filamentous and spheroidal microbes. The annelids, wiwaxiids and priapulids are the first recorded from the Cambrian of Baltica. The File Haidar SCF assemblage is broadly comparable to those recovered from Cambrian basins in Laurentia and South China, though differences at lower taxonomic levels point to possible environmental or palaeogeographical controls on taxon ranges. These data reveal a fundamentally expanded picture of early Cambrian diversity on Baltica, and provide key insights into high‐latitude Cambrian faunas and patterns of SCF preservation. We establish three new taxa based on large populations of distinctive SCFs: Baltiscalida njorda gen. et sp. nov. (a priapulid), Baltichaeta jormunganda gen. et sp. nov. (an annelid) and Baltinema rana gen. et sp. nov. (a filamentous problematicum).     

Gut Contents as Direct Indicators for Trophic Relationships in the Cambrian Marine Ecosystem

Present-day ecosystems host a huge variety of organisms that interact and transfer mass and energy via a cascade of trophic levels. When and how this complex machinery was established remains largely unknown. Although exceptionally preserved biotas clearly show that Early Cambrian animals had already acquired functionalities that enabled them to exploit a wide range of food resources, there is scant direct evidence concerning their diet and exact trophic relationships. Here I describe the gut contents of Ottoia prolifica, an abundant priapulid worm from the middle Cambrian (Stage 5) Burgess Shale biota. I identify the undigested exoskeletal remains of a wide range of small invertebrates that lived at or near the water sediment interface such as hyolithids, brachiopods, different types of arthropods, polychaetes and wiwaxiids. This set of direct fossil evidence allows the first detailed reconstruction of the diet of a 505-million-year-old animal. Ottoia was a dietary generalist and had no strict feeding regime. It fed on both living individuals and decaying organic matter present in its habitat. The feeding behavior of Ottoia was remarkably simple, reduced to the transit of food through an eversible pharynx and a tubular gut with limited physical breakdown and no storage. The recognition of generalist feeding strategies, exemplified by Ottoia, reveals key-aspects of modern-style trophic complexity in the immediate aftermath of the Cambrian explosion. It also shows that the middle Cambrian ecosystem was already too complex to be understood in terms of simple linear dynamics and unique pathways.     

Explaining gregarious behaviour in Banffia constricta from the Middle Cambrian Burgess Shale,British Columbia

Banffia constricta is an enigmatic Burgess Shale animal originally described by Charles Walcott in 1911 as an annelid, and more recently as a stem‐group deuterostome. Interpreted, on the basis of anatomy, to have been bottom‐feeders, there are few other data from which to draw interpretations of Banffia's life habit. A slab of Burgess Shale with a dense aggregation of B. constricta may indicate a gregarious habit for the animal, as taphonomic and stratigraphical data indicate an in situ origin for the assemblage. Clustering of individuals, high density of the individuals and non‐random within‐cluster orientation support the hypothesis that detritus‐feeding B. constricta congregated to feed on a local, rich food source. Presumed opportunistic feeding aggregations have been documented in at least one other Burgess Shale taxon and have been described for other fossil benthic marine invertebrates. Extant benthic marine invertebrates such as holothurians and echinoids exhibit mass feeding behaviour and may serve as modern analogs for the behaviour represented by the B. constricta assemblage.     

Dynamic palaeoredox and exceptional preservation in the Cambrian Spence Shale of Utah

Garson, D.E., Gaines, R.R., Droser, M.L., Liddell, W.D. & Sappenfield, A. 2011: Dynamic palaeoredox and exceptional preservation in the Cambrian Spence Shale of Utah. Lethaia, Vol. 45, pp. 164–177. Burgess Shale‐type faunas provide a unique glimpse into the diversification of metazoan life during the Cambrian. Although anoxia has long been thought to be a pre‐requisite for this particular type of soft‐bodied preservation, the palaeoenvironmental conditions that regulated extraordinary preservation have not been fully constrained. In particular, the necessity of bottom water anoxia, long considered a pre‐requisite, has been the subject of recent debate. In this study, we apply a micro‐stratigraphical, ichnological approach to determine bottom water oxygen conditions under, which Burgess Shale‐type biotas were preserved in the Middle Cambrian Spence Shale of Utah. Mudstones of the Spence Shale are characterized by fine scale (mm‐cm) alternation between laminated and bioturbated intervals, suggesting high‐frequency fluctuations in bottom water oxygenation. Whilst background oxygen levels were not high enough to support continuous infaunal activity, brief intervals of improved bottom water oxygen conditions punctuate the succession. A diverse skeletonized benthic fauna, including various polymerid trilobites, hyolithids, brachiopods and ctenocystoids suggests that complex dysoxic benthic community was established during times when bottom water oxygen conditions were permissive. Burgess Shale‐type preservation within the Spence Shale is largely confined to non‐bioturbated horizons, suggesting that benthic anoxia prevailed in intervals, where these fossils were preserved. However, some soft‐bodied fossils are found within weakly to moderately bioturbated intervals (Ichnofabric Index 2 and 3). This suggests that Burgess Shale‐type preservation is strongly favoured by bottom water anoxia, but may not require it in all cases. □Anoxia, Burgess Shale, Burgess Shale type‐preservation, Langston Formation, Spence Shale Member, Utah.     

First record of the brachiopod Lingulella waptaensis with pedicle from the Middle Cambrian Burgess Shale

Pettersson Stolk, S., Holmer, L. E. and Caron, J ‐B. 2010. First record of the brachiopod Lingulella waptaensis with pedicle from the Middle Cambrian Burgess Shale. —Acta Zoologica (Stockholm) 91 : 150–162 The organophosphatic shells of linguloid brachiopods are a common component of normal Cambrian–Ordovician shelly assemblages. Preservation of linguloid soft‐part anatomy, however, is extremely rare, and restricted to a few species in Lower Cambrian Konservat Lagerstätten. Such remarkable occurrences provide unique insights into the biology and ecology of early linguloids that are not available from the study of shells alone. Based on its shells, Lingulella waptaensis Walcott, was originally described in 1924 from the Middle Cambrian Burgess Shale but despite the widespread occurrence of soft‐part preservation associated with fossils from the same levels, no preserved soft parts have been reported. Lingulella waptaensis is restudied herein based on 396 specimens collected by Royal Ontario Museum field parties from the Greater Phyllopod Bed (Walcott Quarry Shale Member, British Columbia). The new specimens, including three with exceptional preservation of the pedicle, were collected in situ in discrete obrution beds. Census counts show that L. waptaensis is rare but recurrent in the Greater Phyllopod Bed, suggesting that this species might have been generalist. The wrinkled pedicle protruded posteriorly between the valves, was composed of a central coelomic space, and was slender and flexible enough to be tightly folded, suggesting a thin chitinous cuticle and underlying muscular layers. The nearly circular shell and the long, slender and highly flexible pedicle suggest that L. waptaensis lived epifaunally, probably attached to the substrate. Vertical cross‐sections of the shells show that L. waptaensis possessed a virgose secondary layer, which has previously only been known from Devonian to Recent members of the Family Lingulidae.     

Anatomy and lifestyles of Early Cambrian priapulid worms exemplified by Corynetis and Anningvermis from the Maotianshan Shale (SW China)

Accurate information on the anatomy and ecology of worms from the Cambrian Lagerstätten of SW China is sparse. The present study of two priapulid worms Anningvermis n. gen. and Corynetis Luo & Hu, 1999 from the Lower Cambrian Maotianshan Shale biota brings new information concerning the anatomical complexity, functional morphology and lifestyles of the Early Cambrian priapulids. Comparisons are made with Recent priapulids from Sweden (live observations, SEM). The cuspidate pharyngeal teeth of Anningvermis (circumoral pentagons) and the most peculiar radiating oral crown of Corynetis added to the very elongate pharynx of these two forms are interpreted as two different types of grasping apparatus possibly involved in the capture of small prey. Corynetis and Anningvermis are two representative examples of the Early Cambrian endobenthic communities largely dominated by priapulid worms (more than ten species in the Maotianshan Shale biota) and to a much lesser extent by brachiopods. Corynetis and Anningvermis were probably active mud-burrowers and predators of small meiobenthic animals. Likewise predator priapulid worms exploited the interface layer between the seawater and bottom sediment, where meiobenthic organisms were abundant and functioned as prey. This implies that complex prey-predator relationship between communities already existed in the Early Cambrian. This study also shows that the circumoral pentagonal teeth and caudal appendage were present in the early stages of the evolutionary history of the group and were important features of the priapulid body plan already in the Early Cambrian. Two new families, one new genus and new species are introduced and described in the appendix.     

The bivalved arthropods Isoxys and Tuzoia with soft‐part preservation from the Lower Cambrian Emu Bay Shale Lagerstätte (Kangaroo Island,Australia)

Abstract: Abundant material from a new quarry excavated in the lower Cambrian Emu Bay Shale (Kangaroo Island, South Australia) and, particularly, the preservation of soft‐bodied features previously unknown from this Burgess Shale‐type 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.     

New Middle Cambrian bivalved arthropods from the Burgess Shale (British Columbia,Canada)

The morphology of two new bivalved arthropods, Loricicaris spinocaudatus gen. et sp. nov. and Nereocaris briggsi sp. nov. from the middle Cambrian (Series 3, Stage 5) Burgess Shale Formation (Collins Quarry locality on Mount Stephen, Yoho National Park, British Columbia, Canada), is described. The material was originally assigned to the genus Branchiocaris, but exhibits distinctive character combinations meriting its assignment to other taxa. Loricicaris spinocaudatus possesses an elongate and spinose abdomen comparable to the contemporaneous Perspicaris and Canadaspis, as well as chelate second head appendages and subtriangular exopods, comparable to Branchiocaris. Nereocaris briggsi possesses a laterally compressed carapace, elongate and delicate appendages and a medial eye located between a pair of lateral eyes on a rhomboidal eye stalk. Although undoubtedly congeneric with Nereocaris exilis from a slightly younger horizon of the Burgess Shale Formation, N. briggsi differs in overall proportions and segment number, warranting assignment to a new species. The newly described taxa were coded into an extensive cladistic analysis of 755 characters, and 312 extinct and extant panarthropods, including a variety of Cambrian bivalved arthropods from both the Burgess Shale and the Chengjiang Lagerstätten. Cambrian bivalved arthropods consistently resolved as a paraphyletic assemblage at the base of Arthropoda. Important innovations in arthropod history such as the specialization of the deutocerebral head appendages and a shift from a nekton‐benthic deposit feeding habit to a benthic scavenging/predatory habit, the symplesiomorphic feeding condition of Euarthropoda (crown‐group arthropods), were found to have occurred among basal bivalved arthropods.     

A spinose stem group brachiopod with pedicle from the Middle Cambrian Burgess Shale

A new genus and species of a Middle Cambrian stem group brachiopod, Acanthotretella spinosa n. gen. and n. sp., is described from the Burgess Shale Formation. Most of the 42 specimens studied came from the Greater Phyllopod bed (Walcott Quarry) and were collected from five bed assemblages, each representing a single obrution event. Specimens are probably preserved within their original habitat. In contrast to all brachiopods known from the Burgess Shale, the shells of the new stem group brachiopod are often deformed and do not show signs of brittle breakage, which suggests that the valves were originally either entirely organic in composition or, more likely, had just a minor mineral component. Acanthotretella spinosa differs from all the other described Cambrian brachiopods in that it is covered by long, slender and possibly partly mineralized spines that are posteriorly inclined at an oblique angle away from the anterior margin. The spines penetrate the shell and are mainly comparable with the thorn‐like organic objects that have been inferred from early siphonotretoid brachiopods. The pedicle was slender and was composed of a central coelomic region and emerged from an apical foramen at the end of an internal pedicle tube. The finding of a pedicle attached to the macrobenthic algae Dictyophycus and other epibenthos implies that A. spinosa did not have an infaunal mode of life. The visceral region and interior characters are poorly preserved.     

The cuticle of the enigmatic arthropod Phytophilaspis and biomineralization in Cambrian arthropods

Lin, J.‐P., Ivantsov, A.Y. & Briggs, D.E.G. 2011: The cuticle of the enigmatic arthropod Phytophilaspis and biomineralization in Cambrian arthropods. Lethaia, Vol. 44, pp. 344–349. Many non‐trilobite arthropods occur in Cambrian Burgess Shale‐type (BST) biotas, but most of these are preserved in fine‐grained siliciclastics. Only one important occurrence of Cambrian non‐trilobite arthropods, the Sinsk biota (lower Sinsk Formation, Botomian) from the Siberian Platform, has been discovered in carbonates. The chemical compositions of samples of the enigmatic arthropod Phytophilaspis pergamena Ivantsov, 1999 and the co‐occurring trilobite Jakutus primigenius Ivantsov in Ponomarenko, 2005 from this deposit were analysed. The cuticle of P. pergamena is composed of mainly calcium phosphate and differs from the cuticle of J. primigenius, which contains only calcium carbonate. Phosphatized cuticles are rare among large Cambrian arthropods, except for aglaspidids and a few trilobites. Based on recent phylogenetic studies, phosphatization of arthropod cuticle is likely to have evolved several times. □arthropod cuticle, Burgess Shale‐type preservation, fossil‐diagenesis, phosphatization.     

Recent Priapulidae and their Early Cambrian ancestors: comparisons and evolutionary significance

Although priapulid worms form a relatively small phylum in present-day marine environments, they were important animals in Cambrian endobenthic communities. Two Early Cambrian priapulids, namely Xiaoheiqingella peculiaris and Yunnanpriapulus halteroformis nov. gen., nov. sp. from the Maotianshan Shale Lagerstätte of SW China are revised and described. Several key-features of the body plan of Recent Priapulidae are recognized in these two forms: 1) the four-fold body division (introvert, neck, trunk, and caudal appendage); 2) the well-developed introvert armed with ca. 25 longitudinal rows of scalids; 3) the caudal appendage; 4) the pharyngeal teeth arranged in a pentagonal disposition (Xiaoheiqingella); 5) the ventral nerve cord present in Yunnanpriapulus. This morphology indicates close evolutionary relationships with modern priapulids. Xiaoheiqingella and Yunnanpriapulus nov. gen. are tentatively placed within the recent family Priapulidae. The Priapulidae lineage may therefore have a remote origin (Early Cambrian) much older than was previously assumed (Priapulites; Late Carboniferous). The functional morphology of Xiaoheiqingella and Yunnanpriapulus nov. gen. suggests that these two worms were chiefly carnivorous with possible occasional mud-eating habits.     

A palaeoscolecid worm from the Burgess Shale

Palaeoscolecid worms are a ubiquitous group of Early Palaeozoic ecdysozoans that are curiously lacking in the archetypal Cambrian Lagerstätten, the Burgess Shale. Here I describe Scathascolex minor gen. et sp. nov, the first unequivocal palaeoscolecid from this site. Scathascolex is armoured with simple Hadimopanella‐like plates, but lacks smaller platelets, pointing to a close affinity with the Palaeoscolecida sensu stricto. Neither preservational nor environmental factors account for the scarcity of palaeoscolecids in the Burgess Shale, which presumably represents an ecological phenomenon.     

英文贵州中寒武世凯里生物群中宏观藻类化石新材料(英文)

贵州省台江县中寒武世凯里生物群含有丰富的非钙质藻类和具有软躯体后生动物化石 ,它为布尔吉斯页岩型生物群在世界广泛分布提供了更有力的证据。在生物群的宏观藻类中描述了 5个属 5个种 ,包括 2个新属。它们是MarpoliaspissaWalcott、AcinocricusstichusConwayMorrisandRobison、UdotealgaerectaYang、EosargassumsawataYang和RhizophytonzhaoyuanlongiiYang ,并且将凯里生物群中的宏观藻类化石组合与加拿大布尔吉斯页岩生物群中的宏观藻类进行了对比 ,发现两个生物群不仅具有相似的动物化石组成 ,而且宏观藻类化石组成也很相似。     

The cuticular structure of the 495-Myr-old type species of the fossil worm Palaeoscolex,P. piscatorum (?Priapulida)

Latex impressions of the cuticle of a compression fossil of the ? priapulid Palaeoscolex piscatorum, from the Lower Ordovician of Shropshire, demonstrate a complex ornamentation of sclerites similar to isolated material, e.g. Hadimopanella and phosphatized arrays. Each ‘segment‘is defined by an intercalary zone and bears two rows of sub-circular plates with prominent nodes on the upper surface. The intercalary zone bears two narrow grooves and a series of platelets, similar to but smaller than the plates. The remainder of each segment is occupied by microplates. Palaeoscolex piscatorum is fairly similar to a number of other species, including Gamoscolex herodes and Milaculum elongatum. Present evidence suggests the palaeoscolecidans are priapulid worms (or near relatives). Their abundance, combined with records from Burgess Shale-like occurrences, suggest priapulids were a major component of many Lower Palaeozoic benthic communities.     

Graptolite (Hemichordata,Pterobranchia) preservation and identification in the Cambrian Series 3

Due to inadequate preservation, pterobranchs are often difficult to identify in the fossil record, and a better understanding of preservational modes and diagenetic and metamorphic effects is needed for their recognition. Pterobranch hemichordates are common in Cambrian Stage 5 and younger sedimentary rocks, but are frequently overlooked. Often, pterobranch hemichordate colonies have been considered to be algal remains or hydroids. Re‐examination of Cambrian Burgess Shale algae reveals that the genera Yuknessia and Dalyia can be recognized as putative early representatives of pterobranch hemichordates. Distinct fusellar construction of the individual zooidal tubes and branching of the creeping proximal part of the colonies are found in the morphologically similar rhabdopleurid pterobranch genus Sphenoecium. The erect tubes of Sphenoecium do not branch and can reach a length of several centimetres. The development of the fusellar construction in this taxon shows a highly irregular development of the suture patterns, but a fairly consistent height of the individual fuselli. The taxon is widely distributed in the Cambrian Series 3, but has regularly been identified as a hydroid or an alga. Sphenoecium wheelerensis from the Cambrian Wheeler Shale of Utah is described as new.     

New Macroalgal Fossils from Middle Cambrian Kaili Biota in Guizhou Province,China (in English)

Abundant and well-preserved remains of noncalcareous algae and soft-bodied metazoans were collected from Middle Cambrian Kaili biota in Taijiang county, Guizhou Province, China. These remains provide further evidence for the wide geographic distribution of many Burgess Shale taxa. Among the algae, 5 genera (including two new genera) and 5 species are described. They are Marpolia spissa Walcott, Acinocricus stichus Conway Morris and Robison, Udotealga erecta Yang, Eosargassum sawata Yang, and Rhizophyton zhaoyuanlongii Yang. Contrasting the macroalgal fossil assemblage in the Kaili biota with one in the Burgess Shale biota, it is clear that similarity of the Kaili biota and the Burgess Shale biota is reflected by the same content of not only the soft-bodied metazoans, but also the noncalcareous algae.     

Mitogenomics and phylogenomics reveal priapulid worms as extant models of the ancestral Ecdysozoan

Research into arthropod evolution is hampered by the derived nature and rapid evolution of the best-studied out-group: the nematodes. We consider priapulids as an alternative out-group. Priapulids are a small phylum of bottom-dwelling marine worms; their tubular body with spiny proboscis or introvert has changed little over 520 million years and recognizable priapulids are common among exceptionally preserved Cambrian fossils. Using the complete mitochondrial genome and 42 nuclear genes from Priapulus caudatus, we show that priapulids are slowly evolving ecdysozoans; almost all these priapulid genes have evolved more slowly than nematode orthologs and the priapulid mitochondrial gene order may be unchanged since the Cambrian. Considering their primitive bodyplan and embryology and the great conservation of both nuclear and mitochondrial genomes, priapulids may deserve the popular epithet of "living fossil." Their study is likely to yield significant new insights into the early evolution of the Ecdysozoa and the origins of the arthropods and their kin as well as aiding inference of the morphology of ancestral Ecdysozoa and Bilateria and their genomes.     

Community palaeoecology of the early Cambrian Maotianshan Shale biota: Ecological dominance of priapulid worms

The early Cambrian soft-bodied Maotianshan Shale (Chengjiang) biota of Yunnan Province, China provides a critical glimpse of animal life during the heart of the Cambrian radiation. The Shankou biota is the focus of this current work, and 9963 specimens from it have been examined and tallied. This collection of fossils represents a time-averaged assemblage of unknown duration from a 10-meter thick sequence. The predominantly benthic community recovered from this section is presumably autochthonous. This community was buried through several hundred millimeter to centimeter thick burial events. Only specimens interpreted as buried alive, based on either soft-part preservation or fully articulated skeletons, were counted. Algae were too fragmented to be counted. To avoid including synonymous species, diversity was evaluated at the genus level. A total of 57 genera from 9 phyla, encompassing 14 ecological groups, were found in this assemblage. The results reveal that the three most abundant genera comprise 43.2% of all specimens: the tubiform priapulid worm Paraselkirkia (16.0%), the diminutive priapulid worm Sicyophorus (14.3%), and the brachiopod Heliomedusa (12.9%). No other genera total more than 9% of specimens. At the phylum level, there is an interesting dichotomy between taxonomic diversity and ecological dominance. The arthropods are the most diverse phylum (37% of genera) and rank second in relative abundance of specimens (26.3%). The priapulids, however, with only 17.5% of genera is the most abundant group in the assemblage (43.2%). All other phyla, excluding brachiopods (19.6%), represent only 10.9% of the assemblage. Because of their sheer numerical abundance, this study indicates that priapulid worms may have exerted more influence on energy flow and community structure than other phyla in this particular trophic web. This result contrasts strongly with both traditional views of Maotianshan Shale biota palaeoecology, which often claimed arthropod dominance based solely on taxonomic diversity, and the palaeoecology of modern priapulids, which are relegated to marginal marine settings. This result also demonstrates the importance of collecting quantitative relative abundance data when performing palaeoecological investigations.     

A death assemblage of priapulid worms from the Middle Cambrian Burgess Shale

A slab of Burgess Shale (Middle Cambrian), displaying an incomplete exoskeleton of the large arthropod Sidneyia inexpectans and encompassed by nine specimens of the priapulid worm Ottoia prolifica, is interpreted as a death assemblage, with the worms once living off or feeding around a carcass or freshly moulted instar of Sidneyia. Death is thought to have been caused by an obrution event that preserved the organisms in situ.     

山东潍坊寒武系苗岭统乌溜阶馒头组上部的腕足动物

寒武系腕足动物属种多样性高、个体数量丰富、形态差异明显、地理分布广泛,具有辅助寒武系三叶虫生物地层划分和对比的潜力.华北板块寒武系苗岭统沉积和化石记录发育良好,是中国苗岭统的经典研究区之一.前人己针对华北寒武系苗岭统乌溜阶腕足动物的系统古生物学开展了一系列基础工作,但这些相关研究主要集中于辽宁地区,目前对华北其他地区苗...