Middle Cambrian chancelloriids from the Argentine Precordillera

We report, for the first time, and systematically describe chancelloriid from the region, including Chancelloria bella, Allonnia cf. tintinopsis, Al. cf. erromenosa, Al. tripodophora, Archiasterella cf. coriacea, Ar. cf. hirundo, Ar. cf. tetraspina, and Ar. cf. fletchergrully, along with previously reported chancelloriid species (Chancelloria cruceana, C. eros, and Archiasterella sp.). The current chancelloriid fauna is similar in taxonomic composition to the Cambrian Burgess Shale-type biotas and to those of China and South Australia. Based on the sclerite construction, we found that the different articulatory facet types may be used to distinguish Allonnia from Archiasterella, and the number of rays is closely related with the arrangement of sclerite rays. The chancelloriid fauna is found stratigraphically between the Glossopleura trilobite zone of the restricted-shelf facies and the Oryctocephalus trilobite zone of the open-shelf facies, spanning the Wuliuan Stage (Delmaran/Topazan) of the Miaolingian Series, middle Cambrian. This study is significant for better understanding the diversity of this enigmatic and cosmopolitan group in the middle Cambrian warm platform of the Precordillera.     

一些原牙形石、副牙形石和最早的真牙形石的组织学和比较组织学研究

本文主要介绍对采自湘西、辽东和鲁西的寒武纪牙形石进行组织学和比较组织学研究成果中尚未发表的内容。以前认为是原牙形石的属Huyuanodontus的组织学构造与原牙形石、副牙形石以及真牙形石均不相同,而且与任何已知化石类群的组织学构造亦不相同。副牙形石Prooneotodus rotendatus和Prooneotodus gallatini中的一些分子具有厚薄不同的齿冠,应属于真牙形石。在已采集到的副牙形石属Laiwugnathus的所有标本中,既未发现副牙形石生长层构造,也未发现牙本质。在具有典型的副牙形石生长层构造的标本中发现了令人信服的牙本质。在最早的真牙形石Proconodontus muelleri中发现了较复杂的管状牙本质。组织学研究证实Coelocerodontus bicostatus为真牙形石。上述成果以及我国寒武纪牙形石组织学和比较组织学已经发表的成果(如:Dong,2004;Dongetal.,2005等)说明研究寒武纪牙形石必需研究牙形石组织学。目前,正在进行的寒武纪牙形石研究的两项主要工作《厘定寒武纪牙形石的分类》以及《副牙形石和早期真牙形石的谱系分析》,均是以组织学的研究为基础的。     

Middle and Late Cambrian sponge spicules from Hunan, China

Abundant and well-preserved assemblages of disarticulated sponge spicules occur in Middle and Late Cambrian platform carbonates of western Hunan, China. Assemblages recovered from 11 stratigraphic horizons include calcisponges, demosponges, and hexactinellids. Hexactinellida, in particular, are both abundant and diverse in Upper Cambrian carbonates. Comparison with spicule assemblages from Australia indicates that many of these taxa have long stratigraphic ranges, limiting their use in correlation. The morphological diversity of these spicules exceeds that known for living siliceous sponges, supporting the observation that during the Cambrian radiation, sponges, like other metazoans, evolved a variety of architectural forms not observed in later periods. Like conodonts, individual sponges can produce more than one spicule form; thus, an "apparatus genus" concept based on multiple co-occurring elements may eventually prove useful in the biostratigraphic and paleobiological interpretation of disarticulated sponge spicules. Four distinctive forms are recognized as new taxa: Australispongia sinensis new genus and species, Flosculus gracilis new genus and species, Pinnatispongia bengtsoni new genus and species, and Nabaviella paibiensis new species.     

A lower Cambrian protoconodont apparatus from the Placentian of southeastern Newfoundland

A cluster of three pyritized, naturally arranged, conoidal sclerites has been found on a bedding surface in the lower Cambrian Chapel Island Formation in southeastern Newfoundland. The elements are about 4 mm in length and are morphologically similar to protoconodonts but neither their original chemical composition nor internal structure is preserved. Arrangement of the elements suggests that they belonged to an apparatus that performed a grasping function. The specimen is described here as ProtohertzinaEfficacynadia n.sp. This is the oldest hitherto described protoconodont apparatus, apart from clusters of Mongolodus described from the lower Cambrian of the Lesser Himalaya. This paper adds to the scant knowledge of early protoconodonts that we consider to be the earliest biomineralized predators.     

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.     

Proposed GSSP for the base of Cambrian Stage 7, coinciding with the first appearance of Lejopyge laevigata, Hunan, China

The Luoyixi section, exposed in a roadcut along the Youshui River (Fengtan Reservoir), Guzhang County, Hunan Province, China, is proposed as the stratotype for the base of an unnamed stage boundary (base of the Cambrian stage provisionally termed Stage 7). The proposed position of the GSSP is 121.3 m above the base of the Huaqiao Formation, at a horizon coinciding with the first appearance of the cosmopolitan agnostoid trilobite Lejopyge laevigata. The section fulfills all the requirements for a GSSP, and the horizon can be constrained not only with the primary stratigraphic marker (L. laevigata) but also with secondary biostratigraphic, sequence-stratigraphic, and chemostratigraphic correlation tools. The first appearance of L. laevigata is one of the most readily recognizable levels in the Cambrian, and can be correlated with precision to all paleocontinents.     

Ontogeny of the eodiscoid trilobite Tsunyidiscus acutus from the Lower Cambrian of South China

Abstract: The morphology and ontogeny of the eodiscid trilobite Tsunyidiscus acutus Sun is described on the basis of numerous calcified specimens collected from the Lower Cambrian Shuijingtuo Formation in Yichang and Changyang, Hubei Province, South China. An ontogenetic series is established based on the articulated material including the previously unknown protaspides and meraspides (degrees 0 and 1). The material, revealing some prominent morphological changes such as the number of pygidial axial rings, genal spines retained throughout ontogeny and pygidial pleurae from furrowed to unfurrowed, enables a discussion on the trunk segmentation schedule, indicating that somitogenesis and tagmosis occurred independently during the ontogenetic development of T. acutus.     

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。     

Middle Cambrian lingulate brachiopods from the Murrawong Creek Formation,northeastern New South Wales

Fourteen species of lingulate brachiopods are documented from allochthonous limestone blocks of the Murrawong Creek Formation in the southern New England Fold Belt, northeastern New South Wales, Australia. The fauna includes Treptotreta jucunda Henderson and MacKinnon 1981, Treptotreta sp. cf. T. sp. nov. Henderson 1992, Amictocracens teres Henderson and MacKinnon 1981, Stilpnotreta magna Henderson and MacKinnon 1981, Anabolotreta tegula Rowell and Henderson 1978, Neotreta orbiculata Koneva 1990, Linnarssonia sp., Linnarssonia sp. cf. L. ophirensis (Walcott 1912), Pegmatreta clavigera sp. nov., Acrothele subsidua (White 1874), Micromitra sp. cf. M. modesta (Lochman 1940), Micromitra sp. Henderson 1992, Lingulella sp. A Henderson 1992, and Kyrshabaktella certa Koneva 1986.

The associated trilobite assemblages indicate a medial Middle Cambrian age for the blocks, and the stratigraphic ranges of several of the lingulate species have been extended. The fauna displays biogeographic links at the specific level with northeastern and southeastern Australia, New Zealand, Antarctica, North America, Kazakhstan, Siberia, and Britain; the strongest links (four species in common) are with the Georgina Basin in northeastern Australia and the Tasman Formation in New Zealand.     

Silicified Middle Cambrian trilobites from Kyrgyzstan

Abstract:  A medium diversity silicified Middle Cambrian faunal assemblage occurs in an olistolith of bioclastic limestone within Silurian siliciclastic turbidites on the slopes of Arpatektyr Mountain in the eastern Alai Range, Kyrgyzstan. The fauna includes the trilobites Raragnostus cf. mirus , Altikolia kurshabica sp. nov., Corynexochina weberi , Dorypyge richthofeniformis , aff. Jincella sp., Olenoides comptus , Skreiaspis aff. spinosus and Suluktella mambetovi sp. nov. Three of these taxa ( C .  weberi , O .  comptus and R . cf.  mirus ) are considered locally to be characteristic of the Pseudanomocarina Beds, although Pseudanomocarina itself is not present. Altikolia and Suluktella are endemic to early Palaeozoic terranes of Central Asia, Corynexochina also occurs in South China and Skreiaspis is known elsewhere exclusively from the Middle Cambrian of 'West' Gondwana. Because of preservation in full relief, the silicified trilobite fauna allows a detailed understanding of some morphological structures, related especially to trilobite enrolment, otherwise inadequately known for many Mid-Cambrian polymerid trilobites.     

Integrated biostratigraphy and carbon isotopes from the Cambrian Tangwangzhai section,North China

The Tangwangzhai section, western Shandong Province, North China, the type section for the Cambrian Kushan and Chaomitian formations, yielded a diverse and relatively well-preserved conodont fauna, in which we recognize the Westergaardodina orygma, Westergaardodina matsushitai, Muellerodus? erectus, and Westergaardodina aff. fossa–Prooneotodus rotundatus zones of the North China conodont zonation. The Tangwangzhai conodont succession can be correlated not only with the polymerid trilobites occurring in the section but also with the conodont zones established for South China. The first occurrence of Furnishina longibasis and Furnishina quadrata in the upper part of the Westergaardodina matsushitai Zone allows the recognition of the base of the Paibian Stage and Furongian Series in the upper part of the Kushan Formation. The base of the Jiangshanian Stage, in the uppermost Muellerodus? erectus Zone, can be recognized by the presence of Westergaardodina cf. calix close to the base of the Chaomitian Formation. Chemostratigraphic analyses of the Tangwangzhai section show the onset of a positive carbon isotope excursion, referred to the SPICE event, in the upper part of the Kushan Formation at a level corresponding to the first occurrence of F. longibasis and F. quadrata. The base of the Jiangshanian Stage in the section is close to the demise of the SPICE positive excursion.     

A new scyphozoan from the Cambrian Fortunian Stage of South China

Animals with radial symmetry are abundant in the Cambrian Fortunian Stage of South China, but with relatively low diversity: representatives include Olivooides, Quadrapyrgites, carinachitiids, hexangulaconulariids and Pseudooides. Here, we report a new radial animal, Qinscyphus necopinus gen. et sp. nov., from the Fortunian small shelly fauna of southern Shaanxi Province, South China. Qinscyphus necopinus has a cup‐shaped profile, with slightly raised annuli and five groups of triangular thickenings in pentaradial symmetry. This organism has a comparable morphology to, and thus a close affinity with, Olivooides and Quadrapyrgites, and is interpreted as a coronate scyphozoan. This discovery adds a new crown‐group cnidarian to the Cambrian Explosion.     

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.     

An intermediate type of medusa from the early Cambrian Kuanchuanpu Formation,South China

The tetraradial or pentaradial fossil embryos and related hatched individuals from the early Cambrian Kuanchuanpu Formation are of great interest for understanding the early evolution of medusozoans. The phylogenetic and evolutionary significance of their external and internal characters (e.g. manubrium, tentacles, septa and claustra) is still controversial. Here we describe a new pentamerous medusozoan, Hanagyroia orientalis gen. et sp. nov., characterized by five well-developed perradial oral lips around a remarkably large manubrium, a conspicuous equatorial groove, and five short interradial pairs of extensile tentacles at the bell margin. Internally, five broad and stout interradial septa join horizontally to form the claustra. Hanagyroia orientalis lacks the frenula, apertural lappet and velarium seen in coeval microfossils and extant cubozoans. Although H. orientalis resembles extant coronate scyphozoans in its round medusa-like bell margin and equatorial groove, cladistic analysis suggests close affinity with cubozoans. Hanagyroia may represent an intermediate morphological type between scyphozoans and cubozoans. The well-developed oral lips and paired short strong tentacles of Hanagyroia suggest direct development.     

Intraspecific variation of trunk segmentation in the oryctocephalid trilobite Duyunaspis duyunensis from the Cambrian (Stage 4, Series 2) of South China

A detailed exploration of growth and trunk segmentation of the oryctocephalid trilobite, Duyunaspis duyunensis Chang & Chien in Zhou et al. 1977, from the lower Cambrian (Stage 4, Series 2) Balang Formation in western Hunan Province, South China, is presented. Because of the excellent preservation, the complete post‐protaspid ontogenetic series from merapsid degree 0 to the holaspid phase is described. The ontogenetic series reveals new information on morphological changes such as the migration of the posterior branch of the facial sutures (from proparian to opisthoparian) and contraction of the posteromedial notch in the pygidium. The abundance of articulated specimens available from a narrow stratigraphical interval makes this material singularly useful for studying the morphogenesis and post‐embryonic growth of D. duyunensis in comparison with other oryctocephalids. Strong evidence that multiple numbers of pygidial segment are recognized in each meraspid degree as well as in the holaspid period showed unusual intraspecific variability in the rate of trunk segmentation, providing insights into how Cambrian subisopygous trilobites controlled their body patterning, including size, shape and trunk segment number in both thorax and caudal plate during growth.     

Cambrian anemones with preserved soft tissue from the Chengjiang biota, China

The group Cnidaria includes 'jellyfish', soft-bodied anemone and anemone-like forms and calcified corals. These diploblastic organisms have a fossil record extending back to the earliest metazoans of the Neoproterozoic; however certain cnidarians of the subclass Zoantharia, characterized by soft-bodied anemone-like forms, are absent or poorly represented in the fossil record. Despite the paucity of fossils, it is thought that calcification by soft anemone-like animals was responsible for producing the skeleton that allowed the preservation of the first corals. We report discovery of an abundant assemblage of in situ soft-bodied polyps with tissues. They are preserved in exquisite detail and come from the well-known Lower Cambrian Chengjiang biota of Yunnan, China. The soft-bodied polyps display a simple anatomy that is comparable to some extant anemones of the order Actinaria. The new fossils are assigned to Archisaccophyllia kunmingensis n. gen. et n. sp. Their simple and conservative form suggests that these fossils may represent some kind of ancestral rootstock. The preserved life assemblage provides a unique snapshot of Lower Cambrian anemone life and provides clues for relationships with extant actiniarians as well as calcified corals.