The lobopodian Paucipodia inermis from the Lower Cambrian Chengjiang fauna, Yunnan, China

New specimens of Paucipodia inermis Chen, Zhou & Ramsköld, 1995, are described from the Lower Cambrian Chengjiang Lagerstätte in Haikou, Kunming. Details not previously seen in the Chengjiang material appear to be caused by early diagenetic processes. Some features not previously observed in Palaeozoic lobopodians include details of the dermomuscular sac, body cavities, contents of the gut, possible paired ventral nerve ganglia, and a rasping or biting apparatus with teeth. The latter implies a fundamental difference from onychophorans and rules out an ancestral position for Palaeozoic lobopodians. The supposed tail is shown to be the head, and it is shown that this animal possessed nine pairs of lobopods rather than six, as originally stated. The family Paucipodiidae n. fam. is introduced.     

A miniscule optimized visual system in the Lower Cambrian

Simultaneously with the development of animal body plans, probably before the Precambrian, there was an explosive diversification of visual systems. Competition of performance in these visual systems was a critical factor in the evolution of life systems.
Here we analyse the visual system in the lobopod Miraluolishania haikouensis ( Liu et al ., 2004 ) from the Lower Cambrian Chengjiang Lagerstätte, Kunming, China. It consists of a very small eye with a miniscule lens. A physical problem lies in the fact that due to the usual refractive conditions of such a lens, it hardly represents an improvement of the visual quality over the basal pit- or pinhole camera eyes. To develop such a lavish visual system, however, would not have been of any value, if it achieved no more than an equal level or represented even a retrograde step in evolutionary progress. We show how this system may have allowed pattern recognition even under poor light conditions. Optimization of such a tiny eye is costly but is not 'a wasted effort' in evolution. In M. haikouensis ( Liu et al. , 2004 ), an excellently adapted miniscule visual system has become possible.     

Morpho-anatomy of the lobopod Magadictyon cf. haikouensis from the Early Cambrian Chengjiang Lagerstätte, South China

Magadictyon haikouensis (Luo and Hu, 1999) from the Early Cambrian Chengjiang Lagerstätte, an incomplete specimen of a large lobopod with strong appendages, has been regarded as related to the lobopods Microdictyon and Onychodictyon. Newly discovered complete specimens of Magadictyon cf. haikouensis (found by the Early Life Institute field team) show that the taxon, in addition to its strong appendages with appendicules, also had a head bearing similar caecum‐like structures to those of the arthropod Naraoia and Chelicerate, ‘Peytoia’‐like mouthparts and frontal appendages. Because of their similarity, the caecum‐like structures of Magadictyon cf. haikouensis are considered to be homologous with those of stem‐group arthropods. The ‘Peytoia’‐like mouthparts and the frontal appendages are similar to those of the AOPK (Anomalocaris–Opabinia–Pambdelurion–Kerygmachela) group. In addition, the appendages with appendicules show that Magadictyon cf. haikouensis is closely related to Onychodictyon. Therefore, Magadictyon cf. haikouensis is regarded here as a rare transitional form between lobopods and arthropods. Besides, together with other lobopods, the morphology of Magadictyon cf. haikouensis demonstrates that the Cambrian lobopods appear to have been diverse and not particularly closely related to one another, and do not seem to represent a monophyletic clade.     

New Upper Cambrian Lingulata (Brachiopoda) from the Agyrek mountains (northeastern central Kazakhstan)

Two new genera, Repkinella and Aristotreta, and five new species from the class Lingulata (Brachiopoda) are described from the Upper Cambrian olistolith limestone enclosed in the Upper Ordovician olistostrome from the Agyrek mountains (northeastern Kazakhstan). The family Curticiidae Walcott et Schuchert is referred to the order Lingulida, not order Acrotretida, where it was previously placed.     

RHYNCHONELLIFORMEAN BRACHIOPODS WITH SOFT-TISSUE PRESERVATION FROM THE EARLY CAMBRIAN CHENGJIANG LAGERSTÄTTE OF SOUTH CHINA

Abstract:  Cosmopolitan kutorginates, the most abundant Early Cambrian rhynchonelliformean brachiopods, became extinct at the end of the Middle Cambrian. Consequently, any information concerning the anatomy of this peculiar lineage of brachiopods has great phylogenetic significance with regard to their extant relatives for analogies with the stem-group clade. Such data have been supplied from fossils of which the soft parts have been preserved in exceptional detail. A new brachiopod, Kutorgina chengjiangensis sp. nov., from the Early Cambrian Chengjiang Lagerstätte of southern China, is described here. It is the first articulated brachiopod species collected from this deposit. The specimens preserve a set of soft-body parts, i.e. lophophore, digestive tract and pedicle, all previously poorly known in almost all Palaeozoic calcareous brachiopod taxa. The lophophore attains an early spirolophe stage, clearly homologous to that in the coeval lingulids. The digestive tract consists of a mouth, oesophagus, swollen stomach, intestine and a terminal anus. The pedicle protruding between the valves is stout and elongate, with annulated lamellae on the surface, and contains a putative cœlomic cavity. K. chengjiangensis displays the characteristics of the stem group of calcareous brachiopods, and illustrates anatomical similarities between Cambrian phosphatic- and calcareous-shelled brachiopods, thus corroborating that the Brachiopoda are a monophyletic group.     

A NEW ARTHROPOD IN CHAIN-LIKE ASSOCIATIONS FROM THE CHENGJIANG LAGERSTÄTTE (LOWER CAMBRIAN), YUNNAN, CHINA

Abstract:  A new arthropod, Synophalos xynos gen. et sp. nov., is described from the Lower Cambrian of the Chengjiang Lagerstätte, Yunnan, China. It is provisionally assigned to Crustacea, Waptiida and Waptiidae. Just one example of an isolated individual of S .  xynos is known. Typically, individuals of the new species occur together in similar, robustly integrated chain-like associations. Such a strongly linked configuration is apparently unique for any arthropod, fossil or living. The chain-like association is suggested to represent an example of collective behaviour, possibly associated with reproduction, or more likely migration.     

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.     

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.     

昆明海口早寒武世澄江生物群中叶状红藻化石

主要报道了釆自云南省昆明市海口马房村鞍山早寒武世筇竹寺组玉案山段澄江生物群中的叶状红藻-似红叶藻(新属、新种)(Paradelesseria sanguinea Xu,gen.et sp.Nov.)。通过比较形态学研究,探讨了该宏观化石藻类的分类归属与亲缘关系,进一步丰富了澄江生物群生物物种多样性的认识,并为研究早寒武世生物演化及其古环境提供了新的化石证据。同时,通过对现生红藻的比较研究,进一步证明了澄江生物群在云南海口地区发生于一个水深在30m以上的亚潮带和下潮间带的海水环境。     

昆明海口早寒武世澄江生物群中叶状红藻化石

主要报道了采自云南省昆明市海口马房村鞍山早寒武世筇竹寺组玉案山段澄江生物群中的叶状红藻-似红叶藻(新属、新种)(Paradelesseria sanguinea Xu,gen.et sp.Nov.).通过比较形态学研究,探讨了该宏观化石藻类的分类归属与亲缘关系,进一步丰富了澄江生物群生物物种多样性的认识,并为研究早寒武世生物演化及其古环境提供了新的化石证据.同时,通过对现生红藻的比较研究,进一步证明了澄江生物群在云南海口地区发生于一个水深在30 m以上的亚潮带和下潮间带的海水环境.     

Ontogeny of the redlichiid trilobite Eoredlichia intermediata from the Chengjiang Lagerstätte,lower Cambrian,southwest China

A detailed investigation of the morphology and ontogeny of the redlichioid trilobite Eoredlichia intermediata (Bulletin of the Geological Society of China, 3–4, 1940, 333) from the lower Cambrian Yu'anshan Member of the Heilinpu Formation, in Kunming, Yunnan Province, southwest China, is presented. The new material comprises a relatively complete ontogenetic series ranging from the early meraspid to the holaspid period, which reveals more details on morphological variation such as the appearance of bacculae in some holaspid specimens, contraction and disappearance of fixigenal spines, and macropleural spines of the first and second thoracic segments, which are all documented for the first time and can also be used as developmental markers defining ontogenetic phases. Two distinct morphotypes, possibly an expression of intraspecific variation or sexual dimorphism, are distinguished by the morphology of pleural spines of the second thoracic segment in meraspid degree 14 and holaspides. The trunk segmentation schedule of E. intermediata is also discussed and conforms to the protarthrous developmental mode. The distinction of the thoracic region into two portions can be observed during late meraspid and early holaspid periods, which might be considered as a reference for a better understanding on the relationship of tagmosis and growth segmentation among the Cambrian redlichiid trilobites.     

Redescription of the Chengjiang arthropod Squamacula clypeata Hou and Bergström, from the Lower Cambrian, south-west China

The anatomy of the arthropod Squamacula clypeata Hou and Bergström, 1997 from the Lower Cambrian Chengjiang Lagersta¨tte is redescribed based on four newly excavated specimens. The new material was collected from localities recently discovered in the Kunming area, Yunnan Province, south-west China, and preserves remarkable details of the ventral morphology, revealed by preparation. Squamacula clypeata is dorsoventrally flattened and rounded in outline. The cephalon was covered by a wide, short shield, with a large doublure and a pair of uniramous antennae on the ventral side. The thorax consists of nine somites, each protected by a tergite and carrying at least one pair of biramous limbs. The pygidium is covered with a small rounded tergum. The endopod is segmented, equipped with short spines on the inner margin of the coxa and a claw-like structure distally, and the exopod flap-like, fringed with setae. The limbs in the pygidium are like those in the thorax in shape. Squamacula was most probably a nektobenthic predator. The spinose endopod could walk, grasp and grind. The large flap-like exopod was adapted for swimming and respiration. Its affinities lie with the Arachnomorpha, but the relationships with other known taxa remain ambiguous.     

New and poorly known acrotretid brachiopods (Class Lingulata) from the Cedaria-Crepicephalus zone (late Middle Cambrian) of the Great Basin, USA

Seven new late Middle Cambrian (Cedaria-Crepicephalus zone) acrotretid species are described from the Great Basin, USA. The species belong to five genera of which Lensotreta is new. The following new species are described: Anabolotreta? glabra, Anabolotreta mogota, Canthylotreta crista, Dactylotreta elegantula, Lensotreta perplexa, Opisthotreta transversa, and Opisthotreta indistincta. The shell structure of Canthylotreta is described for the first time based on new material of the type species Canthylotreta marjumensis and of the new species C. crista. The shell of Canthylotreta includes two types of shell fabric, camerate and columnar. Moreover, parts of the shell show transitional textures, supporting the view that the camerate shell structure may has originated from a columnar fabric. Picnotreta lophocracenta Robson and Pratt, 2001, recently described from western Newfoundland, is also described from the new occurrence in the Great Basin.     

Lower Cambrian (Botomian) polycystine Radiolaria from the Altai Mountains (southern Siberia, Russia)

Relatively well-preserved polycystine Radiolaria are here described from Lower Cambrian (Botomian) strata of the Shashkunar Formation, Altai Mountains in southern Siberia (Russia). These radiolarians display a test formed of a disorderly and three-dimensionally interwoven meshwork of numerous straight and curved bars branching from a five-rayed point-centered spicule located within the inner shell surface. The shell structure allows their assignment to the family Archeoentactiniidae, thus extending the known age range of the family down to the Lower Cambrian. The Botomian age is based essentially on trilobites (Parapagetia-Serrodiscus zone), but also on archaeocyathids identified in earlier publications. The study of the radiolarian-bearing sedimentary sequence confirms the presence of polycystine radiolaria in the external platform environments of Lower Cambrian ecosystems.     

Anatomy and lifestyle of Kunmingella (Arthropoda, Bradoriida) from the Chengjiang fossil Lagerstätte (lower Cambrian; Southwest China)

An updated reconstruction of the body plan, functional anatomy and life attitude of the bradoriid arthropod Kunmingella is proposed, based on new fossil specimens with preserved soft parts found in the lower Cambrian of Chengjiang and Haikou (Yunnan, SW China) and on previous evidence. The animal has a single pair of short antennae pointing towards the front (a setal pattern indicates a possible sensory function). The following set of seven appendages (each composed of a 5-segmented endopod and a leaf-like exopod fringed with setae) is poorly differentiated, except the first three pairs (with possible rake-like endopodial outgrowths, smaller exopods) and the last pair of appendages (endopod with longer and more slender podomeres). The endopods are interpreted as walking legs with a possible role in handling food particles (marginal outgrowth with setae). The leaf-like exopods may have had a respiratory function. The trunk end is short, pointed, flanked with furcal-like rami and projects beyond the posterior margin of the carapace. The attachment of the body to the exoskeleton is probably cephalic and apparently lacks any well-developed adductor muscle system. The inferred life attitude of Kunmingella (e.g. crawling on the surface of the sediment) was that of a dorsoventrally flattened arthropod capped by a folded dorsal shield (ventral gape at least 120°), thus resembling the living ostracode Manawa. The animal was also probably able to close its carapace as a response to environmental stress or to survive unfavourable conditions (e.g. buried in sediment). The anterior lobes of the valves are likely to have accommodated visual organs (possibly lensless receptors perceiving ambient light through the translucent head shield). Preserved eggs or embryos suggest a possible ventral brood care. The presence of Kunmingella in coprolites and its numerical abundance in Chengjiang sediment indicate that bradoriids constituted an important source of food for larger predators. Kunmingella differs markedly from the representatives of the crown group Crustacea (extant and Cambrian taxa) and from the stem group derivatives of Crustacea (exemplified by phosphatocopids and some ‘Orsten’ taxa) in showing no major sign of limb specialization (e.g. related to feeding strategies). Although it resembles other Chengjiang euarthropods in important aspects of its body plan (e.g. uniramous antennae, endopod/exopod configuration), Kunmingella possesses several features (e.g. antennal morphology, post-antennular appendages with 5-segmented endopods) which support the view that bradoriids may be very early derivatives of the stem line Crustacea.     

Microstructure of the linguliformean brachiopod Linnarssonia from the Lower Cambrian of Sichuan, China

Acrotretoids, one of the oldest brachiopod groups, are abundant in the Lower Cambrian Jiulaodong Formation. The shell of Linnarssonia sp. is composed of two layers: a primary layer and a columnar secondary layer. The primary layer is mostly exfoliated, resulting in exposure of the openings to the central canal of the columns. Filae are seen on the surface of the columnar layer, indicating that the columnar secondary layer has influenced changes in ornament on the shell surface. The larval shell has only very weak ripples; the post-larval shell has obvious concentric ribs. Small pits of variable shape cover almost the entire shell surface. The secondary layer is composed of several columnar laminations, each of which comprises both the upper and lower laminae and the cylindrical columns between them. On the inner side of shell the thin columnar laminations increase. The new microstructural data show that two shell layers are developed in Early Cambrian acrotretoid brachiopods; the columnar lamination may be a primitive feature of the microstructural development of the Brachiopoda and may help establish the affinity between different stem-group brachiopods.     

First report of Schizopholis (Lingulata,Brachiopoda) from the Tsinghsutung Formation (Cambrian Series 2, Stage 4) in Guizhou,China

Schizopholis Waagen, 1885 is a genus of linguliform brachiopod, which is known from Cambrian Stage 4 to the Wuliuan Stage of Australia, Antarctica, Pakistan and China. Recently, new material of Schizopholis was discovered from the upper part of the Tsinghsutung Formation (Cambrian Series 2, Stage 4) near Balang village, Jianhe County, Guizhou Province, China. These specimens display the oval pedicle opening in the ventral valve, a median tongue and a pair of tubercles in the dorsal valve that are characteristic features of Schizopholis napuru (Kruse, 1990). This is the first time that this species has been described from Guizhou Province, China. Previously, fossils of this species are usually preserved in carbonate deposits, but the new material documented herein preserved in mudstone of the Tsinghsutung Formation, providing new information regarding both the paleogeographic distribution and paleoecology of this species.     

Stratigraphic and geographic distribution of acrotretids (Brachiopoda,Lingulata) in the Middle and Late Cambrian

The analysis of the taxonomic composition and distribution of acrotretids (Brachiopoda) in the Middle Cambrian and early Late Cambrian shows that, in the later half of the Cambrian, the order Acrotretida was the most abundant brachiopod order and many of its representatives were cosmopolites. The structure, mode of life, and biological features of acrotretids, along with the arrangement of continents with epicontinental seasmostly in the low latitudes, promoted the wide dispersal of this group on the Earth in the Cambrian.