A new assemblage of dabashanellids (Crustacea: Phosphatocopida) from Cambrian Stage 3 of western Hubei Province,South China

Dabashanellids are univalved phosphatocopid crustaceans, and are among the earliest crustaceans known so far. They were reported mainly from the Cambrian Stage 3 of China, but only a single species was established. Here I report a new assemblage of dabashanellids from the Cambrian Stage 3 Shuijingtuo Formation in western Hubei Province, South China. All specimens are sub-millimetre in length, and are preserved as three-dimensional carbonaceous hollow shields. Five species of Dabashanella were recognized, including the previously reported D. hemicyclica, three new species, D. longa n. sp., D. semiorbiculata n. sp., D. unispinata n. sp., and an indeterminate form Dabashanella sp. In addition, five indeterminate forms of arthropods were recovered. These dabashanellids represent part of a meiofauna that lived in the off-shore, deeper environments of mid-northern Yangtze Sea during Cambrian Age 3. This study shows greater morphological diversity and ecologic disparity of dabashanellid crustaceans, and supports the previous suggestion that the invasion of meiofaunal ecdysozoans into the off-shore, deeper environments probably occurred simultaneously with their radiation in the shallow water.     

Early Cambrian organophosphatic brachiopods from the Xinji Formation,at Shuiyu section,Shanxi Province,North China

Abundant and diverse small shelly fossils have been reported from Cambrian Series 2 in North China, but the co-occurring brachiopods are still poorly known. Herein, we describe seven genera, five species and two undetermined species of organophosphatic brachiopods including one new genus and new species from the lower Cambrian Xinji Formation at Shuiyu section, located on the southern margin of North China Platform. The brachiopod assemblage comprises one mickwitziid (stem group brachiopoda), Paramickwitzia boreussinaensis n. gen. n. sp., a paterinide, Askepasma toddense Laurie, 1986, an acrotretoid, Eohadrotreta cf. zhenbaensis Li and Holmer, 2004, a botsfordiid, Schizopholis yorkensis (Holmer and Ushatinskaya in Gravestock et al., 2001) and three linguloids, Spinobolus sp., Eodicellomus cf. elkaniiformis Holmer and Ushatinskaya in Gravestock et al., 2001 and Eoobolus sp. This brachiopod assemblage suggests a late Age 3 to early Age 4 for the Xinji Formation and reveals a remarkably strong connection with coeval faunas from East Gondwana, particularly the Hawker Group in South Australia. The high degree of similarity (even at species level) further supports a close palaeogeographic position between the North China Platform and Australian East Gondwana during the early Cambrian as indicated by small shelly fossil data.     

The Cambrian brachiopod fauna from the first-trilobite age Shuijingtuo Formation in the Three Gorges area of China

The Yangtze platform of South China offers evidence within its Ediacaran–Cambrian geological record of the Cambrian explosion and diversification events in metazoan history. To understand the explosive radiation of animals and the environments in which it took place, the basal Cambrian fauna succession of the Aijiahe section in the Three Gorges area, western Hubei Province, has been studied, revealing the earliest brachiopod fauna (Tsunyidiscus trilobite Zone) in this region, which was dominated numerically by acrotretoids. This is accompanied by abundant skeletal fossils including minute well-preserved phosphatized archaeocyath cups and an assortment of abundant sponge spicules, chancelloriids, mollusks, hyoliths, and bradoriids, retrieved by acid-etching limestone interbeds in the black shale-dominated Shuijingtuo Formation (Series 2). The brachiopods comprise two species of acrotretoids, two types of botsfordiids (Botsfordiidae gen. et sp. indet. A and B), and four species of linguloids. Of the latter, Spinobolus popovi n. gen. n. sp. is strikingly distinctive and typified by spine-like ornamentation seen for the first time in the lower Cambrian; the remaining three linguloid genera, Palaeobolus, Eoobolus, and Lingulellotreta, have a trans-paleocontinental distribution. The Three Gorges Shuijingtuo brachiopod assemblage differs from that of the upper Atdabanian Stage (Cambrian Stage 3) in Siberia and South China, but shows great similarities with those discovered in the Tsanglangpuan (equivalent to Botoman or Stage 4) Stage of eastern Yunnan Province, Siberia, and South Australia, suggesting a much more prolonged sedimentary hiatus in basalmost Shuijingtuo Formation of the Three Gorges area than previously expected. The presence of such unconformities provides a caveat to stable isotope-based correlations that involve a number of discussions of global ocean geochemical changes across the time interval that witnessed Cambrian explosion of metazoans.     

峡东地区寒武纪水井沱组下段双瓣壳类节肢动物系统古生物与个体发育研究

双瓣壳类节肢动物在全球寒武纪海洋中广泛分布,是寒武纪时期布尔吉斯页岩型化石生物群的重要组成类群和典型代表。它们的起源、演化及生态学研究是对早期后生动物演化研究的重要内容。本文详细描述了峡东地区寒武系第二统第三阶水井沱组下段两种双瓣壳类节肢动物,Caudicaella bispinata (Cui and Huo,1990) comb.nov.和Sunella grandis Huo,1965。依据新建的Caudicaella属征,对孙氏虫科的鉴定特征进行了修订。首次研究了孙氏虫科两属种壳瓣的生长发育模式,揭示了壳瓣高长比的等速生长和C.bispinata基刺相对于壳长的异速生长关系。元素扫描分析研究表明,长阳地区天柱山村剖面化石为碳质压膜保存。功能形态学研究认为,C.bispinata是远洋浮游型生物,其广泛的古地理分布有望为寒武纪早期全球生物地层对比提供新的化石依据。     

Simognathus coreensis, a new halacarid mite (Halacaridae: Acari) from Korea

Simognathus coreensis n. sp. is described on the basis of the specimens collected from Youngdeok, the east coast of South Korea. This is the first record of this genus from Korea. Diagnostic features are as follows: big cornea present on ocular plate, covering major portion of it; lateral claws II–IV with accessory process which contain about 5 minute (meaning `very small') teeth, and lateral claws smooth ventrally; prominent foveae on all telofemora; anterodorsal and posterodorsal plate subequal; lateral side of anterior epimeral plate foveate. This species is similar to S. corneatus Otto and S. exoticus Otto. Dissimilarities are discussed. Abbreviations: AD, anterodorsal plate; AE, anterior epimeral plate; ds, dorsal setae of idiosoma I; GA, genitoanal plate; GO, genital opening; PE, posterior epimeral plate; EP I, epimeral process I; PGS, perigenital setae; P1-P3, first to third palpal segment; SGS, subgenital seta.     

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).     

A new early Cambrian bivalved euarthropod from Yunnan,China and general interspecific morphological and size variations in Cambrian hymenocarines

The hymenocarines were a major and diverse group of euarthropods featured by a bivalved head carapace and a segmented trunk comprising tergo-pleural rings notably from the Cambrian Burgess Shale-type Lagerstätten. Here we document a new ~50 mm long hymenocarine Xiazhuangocaris chenggongensis n. gen. n. sp. from the Xiazhuang fossil assemblage, a slightly younger occurrence of the Chengjiang Lagerstätte within the lower Cambrian Hongjingshao Formation (Cambrian Series 2, Stage 3) in Chenggong, Yunnan, southwestern China. X. chenggongensis is characterized by the bivalved carapace with each valve bearing a protruded anterior tip and a prominent posterior notch, which resembles the P-element of the radiodont Hurdia and is unique among the hymenocarines. The trunk consists of at least 13 tergo-pleural rings including presumably eight abdominal ones terminating in a pair of ovate caudal rami. With the body organization and morphological features closest to waptiids, X. chenggongensis represents a ‘larger’ waptiid-like hymenocarine. The morphometric analysis recognizes the family-level groupings of Cambrian hymenocarines based on the number of tergo-pleural rings and the proportion of exposed trunk length, indicating that these are useful characters for studying hymenocarine morphology and phylogeny. Cambrian hymenocarines exhibited great interspecific body size variations even between sister species of the same family, further suggesting that niche diversification happened on the family level and even among phylogenetically close genera or species during the Cambrian explosion.     

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.     

Reconsideration of the supposed naraoiid larva from the Early Cambrian Chengjiang Lagerstätte, South China

The Chengjiang Lagerstätte in the Lower Cambrian of South China yields a small, larva‐like arthropod, which was considered to be a protaspis of naraoiids by many authors. The discovery of a large number of well‐preserved specimens from many new localities has allowed the original study to be revised. The relatively large size, stable morphology and unusual structure of the appendages indicate that these specimens represent adults of a new arthropod, Primicaris larvaformis. The larva‐like outline is considered to have arisen by the heterochronic process of progenesis. In addition, this animal displays primitive aspects of bodyplan and limb morphology that suggest a basal position within arachnomorphs, or perhaps even arthropods, and the similarities to the Vendian arthropod‐like animal Parvancorina probably provide an evolutionary link between Vendian forms and Cambrian arthropods.     

A myriapod-like arthropod from the Upper Cambrian of East Siberia

Although the fossil record of biramous arthropods commences in the Lower Cambrian, unequivocal uniramous arthropods do not appear until the Upper Silurian, in association with terrestrial biotas. Here we report an Upper Cambrian marine arthropod from East Siberia that possesses some significant myriapodan features. The new arthropod,Xanthomyria spinosa n. gen., n. sp., closely resembles examples of archipolypodans from the Late Palaeozoic. If this resemblance genuinely represents myriapod affinities, this would be the first convincing myriapod from the Cambrian. Suggestions of an early branching point of the myriapods from other arthropods would be consistent with this. Conversely, an as yet poorly known clade of multi-segmented arthropods may exist in the Cambrian, with no close affinities to the myriapods.      

Lapworthellids and other skeletonised microfossils from the Cambrian Stage 3 of the northern Montagne Noire,southern France

The Montagne Noire (southern France) possesses one of the most complete Cambrian successions in the western peri-Gondwana margin and might provide a good stratigraphic reference for both regional charts and international correlations. However, to date, the lower Cambrian succession of the northern Montagne Noire has been supposed to be devoid of biostratigraphically significant fossils. The complex tectonostratigraphic framework of the area (a range divided into Axial Zone, northern and southern Montagne Noire) exacerbated problems related to regional correlations and palaeogeographic reconstructions. As a result, the chronostratigraphic context of the lower Cambrian of northern Montagne Noire is still uncertain and stratigraphic reports have broadly relied on putative lithostratigraphic correlations with the southern Montagne Noire. The purpose of this study is to characterise, for the first time, the fossil record of carbonate beds and lenses of the northern Montagne Noire occurring at the top of the siliciclastic-dominated Marcory Formation, in order to provide regional bio- and chronostratigraphic constraints on lower Cambrian strata. Moreover, this study is aimed at improving international chronostratigraphic correlation. Carbonate beds and lenses cropping out along the Orque Cliff, in the Mélagues thrust slice, were investigated. They yielded a faunal assemblage constituted of molluscs (Igorella cf. ungulata and Igorella moncereti n. sp.), hyoliths (Conotheca brevica), chancelloriids (Archiasterella cf. pentactina and Allonnia sp.) and tommotiids (Lapworthella rete). L. rete is recorded in upper Meishucunian (Cambrian Stage 3) strata of the Yangtze Platform (South China) where it is used as index fossil of the Cambrian Stage 3 Sinosachites flabelliformis–Tannuolina zhangwentangi Assemblage Zone. Therefore, the presence of this tommotiid provides evidence that the studied carbonate beds and lenses are Cambrian Age 3 (Atdabanian according to the Siberian chart). The upper part of the Marcory Formation in the Mélagues slice, dated as Cambrian Stage 3, might represent a lateral equivalent of the mixed (carbonate-siliciclastic) Pardailhan Formation defined in the southern Montagne Noire.     

Problematic cap-shaped fossils from the Lower Cambrian of North-East Greenland

Three species ofOcruranus Liu, 1979 are described from the Bastion Formation of North-East Greenland, of late Early Cambrian (middle Dyeran of North American usage) age, representing the youngest record of a genus originally described from the earliest Cambrian Meishucunian Stage of China. An accompanying species, tentatively assigned toXianfengella He &Yang, 1982, seems also to be present in South Australia in strata of late Early Cambrian (Botoman of Siberian usage) age, although also this genus was described originally from the Meishucunian.Ocruranus andXianfengella from China have been interpreted as possibly parts of coeloscleritophoran scleritomes, perhaps halkieriids, rather than individual molluscan shells. Their shell form is not typical of helcionelloids which otherwise dominate the Early Cambrian molluscan record, but conclusive evidence of affinity is not forthcoming from the Greenland records. New taxa:Ocruranus septentrionalis n. sp. andOcruranus tunuensis n. sp.      

A new rhynchonelliform brachiopod Longtancunella with soft-part preservation from the Hongjingshao Formation (Cambrian Stage 3) in Yunnan,South China

Rhynchonelliform brachiopods made their first appearance in early Cambrian, and became a major group within the palaeozoic evolutionary fauna since late Cambrian. Exceptionally preserved fossils from the early Cambrian Lagerstätten provide valuable chances to investigate their phylogeny and ecology. Longtancunella is one of the most interesting early rhynchonelliforms, and has been mainly recovered from the Chengjiang Lagerstätte (Series 2, Stage 3). Here, we report a new rhynchonelliform Longtancunella xiazhuangensis n. sp. from the lower Hongjingshao Formation (upper Stage 3) in Yunnan Province, China. These specimens were well preserved with soft parts, including pinnate mantle canal system and a pedicle. It is identified as a new species based mainly on its difference in shell ornamentations, pinnate mantle canals and pedicle morphology from the type species. Its pedicle looks unusually stout with distinct annulated lamellae on the surface, and reveals crucial evidence in illustrating its ecology and settling strategy as an early marine epifauna. The ecological interaction between L. xiazhuangensis and other marine animals also provides insights into the food web structure in the early Cambrian.     

A first report of Sphenothallus Hall, 1847 in the Cambrian of Variscan Europe

Ten specimens of two phosphatic fossils have been recently discovered in lower and middle portions of Middle Cambrian Jince Formation in the Czech Republic. They are attributed to the genus Sphenothallus Hall, 1847 and described as two separate species; comparatively small conchs are described as S. kozaki sp. nov., the much larger specimens characterized by its smooth and partly flexible organo-phosphatic walls of shell are determined as ?S. kordulei sp. nov. Sphenothallus is known to range from Cambrian to Permian and accommodates numerous species. However, its Cambrian distribution is considerably restricted. Generally rare specimens have been described from Lower to Middle Cambrian of Laurentia and from the Lower Cambrian of Gondwana and peri-Gondwana. The new record of Sphenothallus from the Jince Biota represents a notable extension of their geographic range.     

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.     

Internal soft-tissue anatomy of cambrian 'orsten' arthropods as revealed by synchrotron x-ray tomographic microscopy

The world-famous ‘Orsten’ Konservat-Lagerstätte has yielded detailed information about Cambrian arthropods and their morphology. Internal organs or soft tissues have, however, rarely been reported, an obvious palaeobiological drawback. In this study, we employed synchrotron radiation X-ray tomographic microscopy (SRXTM) to study microscopic ‘Orsten’ arthropods from the Cambrian of Sweden: Skara minuta and two phosphatocopine species, Hesslandona sp. and Hesslandona trituberculata. This exceptionally high-resolution technique reveals internal organs or soft tissues that allow detailed comparison with equivalent structures in extant crustaceans and functional inferences to be made. The S. minuta specimen shows the digestive system and muscles that extend to the extremities. The slanting anterior portion of the head and anterior position of the mouth with a straight oesophagus suggest a primarily brushing and scraping way of feeding. The prominent head appendage muscles indicate muscle strength and good capacity for food manipulation. In the phosphatocopines the bulbous labrum is one of the most prominent morphological structures of the body. All specimens analysed reveal pairs of muscle bundles within the labrum. Based on comparisons with extant crustacean relatives, these muscles would fulfil the function of moving the labrum up and down in order to open the buccal cavity. The results of this pilot study demonstrate that there is still much to be learned about the ‘Orsten’ taxa.     

A taxonomic study of Chinese species of the insidiosus group of Metaphycus (Hymenoptera,Encyrtidae)

In this paper, twelve insidiosus-group species of the genus Metaphycus Mercet from China are reviewed. Five species, M. corniae sp. n., M. cylindricus sp. n., M. deltoideus sp. n., M. transversus sp. n. and M. yaanensis sp. n., are described as new to science. A key to the females of these species is given to facilitate species recognition. Photomicrographs are provided to illustrate morphological characters of these species. All specimens, unless otherwise specified, are deposited in the National Zoological Museum of China, Institute of Zoology, Chinese Academy of Sciences, Beijing.     

Latest Permian Palaeolithocycliidae (Radiolaria) from South China

The family Palaeolithocycliidae Kozur and Mostler was formerly thought to be ranging from Devonian to Carboniferous. However, a lot of radiolarians assignable to this family were discovered in the late Changhsingian (Latest Permian) of South China. Six species, including Palaeolithocyclia pilata n. sp., Palaeolithocyclia platta n. sp., Paramphibrachium woni n. sp., Klaengspongus spinosus Sashida, Klaengspongus formosus n. sp. and Klaengspongus umbilicatus n. sp., have been identified. In this paper, these species are illustrated and described.     

A new oryctocephalid trilobite from the Balang Formation (Cambrian Stage 4) of northwestern Hunan,South China,with remarks on the classification of oryctocephalids

A new trilobite, Longaspis paiwuensis n. gen. n. sp., from the Balang Formation (Cambrian Stage 4) in northwestern Hunan, South China, is described. This rare trilobite adds to an expanding taxonomic list of organisms recognized from the Balang Lagerstätte, a deposit of exceptional preservation from the Cambrian. Longaspis paiwuensis is an unusually large-sized, micropygous oryctocephalid trilobite that has proparian facial sutures, pit-like lateral glabellar furrows, up to 17 thoracic segments, and a distinct medial notch in the pygidium; it lacks marginal spines.The classification of the family Oryctocephalidae is reviewed. Three subfamilies are recognized, and Longaspis n. gen. is assigned to the subfamily Oryctocarinae.