Kaili Formation Research Articles

Flourishing chancelloriids from the Cambrian Kaili Biota of South China

ABSTRACT Diverse chancelloriids from two sections of the Kaili Biota (Cambrian Wuliuan Stage) in Guizhou Province, China, are systematically described. A total of 25 complete individuals were collected from calcareous silty mudstones of the Cambrian Kaili Formation and are assigned to 3 genera and 6 species, including Archiasterella anchoriformis sp. nov., Chancelloria zhaoi sp. nov., C. eros, Allonnia erjiensis, Al. phrixothrix, and Al. sp. The new species Ar. anchoriformis with sclerites characterised by a large angle between two marginal-lateral rays and an obvious apical tuft represents the first unambiguous Archiasterella scleritome in South China. The C. zhaoi is dominated by a series of bilaterally symmetrical, rosette-like sclerites that composed of five or six lateral rays and a central ray. Moreover, based on a careful survey of the spatial-temporal distribution of chancelloriids (including both scleritome and isolated sclerite fossils) in South China, two flourishing ages, though may be related to preservational bias, of this metazoan group are recognised: 1) a significant diversification in the upper Stage 2 to Stage 3 and 2) a thriving in the Wuliuan Stage.

Assessment of morphological variation in the early Cambrian trilobite Protoryctocephalus

ABSTRACT Studies focused on morphological variation are key for chrono- and biostratigraphy. Morphological variability can be induced by biological and taphonomical biases. Their distinction can become a difficult task due to the lack of population control. Here, we analyse three populations belonging to the genus Protoryctocephalus, two populations from China (P. arcticus and P. balangensis) and a third population of P. arcticus from Greenland. Protoryctocephalus balangensis was collected from the lowermost part of the Kaili Formation where fossils are tectonically deformed while P. arcticus from the ‘Tsinghsutung’ and Greenland specimens are non-deformed. Geometric morphometrics analysis shows that these three populations indeed belong to the same species. However, the large allometry measured in P. balangensis compared with the ‘Tsinghsutung’ population and the Greenland population, which is represented by meraspid and early holaspid individuals, suggested that the morphological variation is taphonomically controlled and non-biological. The results suggest that Protoryctocephalus arcticus from the ‘Tsinghsutung’ Formation is suitable for international correlation, and further studies focus on different aspects such as ontogeny, segment development or fluctuating asymmetry and modularity.

Stalked eocrinoids attached onto hyolithids with helens from Cambrian Kaili Formation in Jianhe, Guizhou, South China

Reliable fossil record regarding symbiotic relationship is a key to understanding the ecology and environment in Cambrian. Herein, we exhibited an exceptionally well preserved hyolithid with intact stalked eocrinoids attaching on the operculum and conch venter, indicating the symbiotic relationship between hyolithids and eocrinoids. By that we carried out a reconstruction for their epibiotic relationship on the Cambrian sea floor. The ontogenetic features of two eocrinoids on the operculum indicated they were immature (in the early stage of ontogeny). And considering the correlation between the orientation of eocrinoids and the mud flow in event-induced rapid burial, we proposed the orientation of eocrinoids implies the direction of mud flow. Additionally, based on specimens with signs of transport, we found that taphonomical factors besides ecological factors could also lead eocrinoids to preferentially attach on the dorsal or dorso-lateral surface of the conch, which was usually interpreted as a mutualism in previous reports though.

An atypical Burgess Shale-type fossil assemblage from Cambrian Stage 4 of the Jingshan area, South China: Taphonomy, palaeoecology, and global correlations

Burgess Shale-type biotas have been widely reported from the Cambrian in North America, Siberia, Greenland, China, and Australia; they are crucial in reconstructing the biotic evolution and ecological interactions of early metazoans. Here, we report an atypical Burgess Shale-type fossil assemblage from the Shilongdong Formation (Cambrian Stage 4) in the Jingshan area, central Hubei Province, South China. The newly recovered fauna is preserved in a nearly two-meter-thick yellowish-green shale unit intercalated within the massive dolomite and dolomitic limestone succession of the upper Shilongdong Formation. The fossil-bearing shale unit is likely deposited in the deep subtidal zone below storm wave base with occasional influence of weak storm flows, which was likely situated in the relatively low location with the interior of the restricted carbonate platform. The presence of the trilobite Redlichia guizhouensis assigns the Jingshan fossil assemblage to the Longwangmiaoan Stage (Cambrian Series 2, Stage 4), which is of similar age to the Jianhe biota, but younger than the Guanshan, Balang, and Shipai biotas, and slightly older than the Kaili biota, South China. The Jingshan assemblage is fossiliferous, containing common shelly and some soft-bodied fossils. It comprises algae, brachiopods, arthropods, hyoliths, priapulid worms, echinoderms, possible cnidarians, molluscs, and some enigmatic organisms. The fossils retain soft parts, including brachiopods with pedicles and delicate setae, a naraoiid with the antenna preserved and digestive tracts. The diversity of the assemblage is limited compared with better-known biotas of similar age, but investigation is at a preliminary stage. It is an important geographical extension of the Burgess Shale-type biotas in China and provides more information about the Cambrian Explosion of life and biodiversity by comparing fossiliferous horizons in a chronological framework.

The bivalved arthropod Tuzoia from the Balang Formation (Cambrian Stage 4) of Guizhou, China, and new observations on comparative species

AbstractTuzoia is a large, bivalved Cambrian arthropod having a widespread distribution in shallow‐shelf to deeper marine Lagerstätten; stratigraphically it ranges from Cambrian Series 2 through the Miaolingian Series. In the present study, three species are recognized from relatively deep‐water deposits of the Balang Formation (Cambrian Stage 4) of Guizhou, South China: Tuzoia sinensis Pan, 1957, T. bispinosa Yuan et Zhao, 1999 and T. lazizhaiensis sp. nov. The new species is unique in having 6–10 small marginal spines on the dorsal margin, an inflated anterior margin with three short, closely spaced marginal spines. These remains, which usually occur as disarticulated valves, are inferred to be parautochthonous. One new specimen of T. lazizhaiensis shows a stalked eye and antenna. New Tuzoia material from the Kaili Biota (Cambrian: Wuliuan Stage) of Guizhou, and from the Guanshan Biota (Cambrian Stage 4) of Yunnan, China, provide additional comparative information about the genus. Some new specimens of T. bispinosa from the Kaili Biota provide information on valve morphology and palaeoecology. One specimen of T. sinensis from the Guanshan Biota provides information on the appendages, and one specimen of T. tylodesa, from the Guanshan Biota adds provides information on the trunk and appendages.

Global Standard Stratotype-Section and Point (GSSP) for the conterminous base of the Miaolingian Series and Wuliuan Stage (Cambrian) at Balang, Jianhe, Guizhou, China

The International Commission on Stratigraphy and the IUGS Executive Committee have recently ratified a Global Standard Stratotype-section and Point (GSSP) defining the conterminous base of the third series and the fifth stage of the Cambrian System. The series and the stage are respectively named the Miaolingian Series and Wuliuan Stage, after the Maioling Mountains in southeastern Guizhou and the Wuliu sidehill, Jianhe County, in eastern Guizhou Province, South China, where the GSSP is located. The GSSP is exposed in a natural outcrop near the Balang Village at a position of 26° 44.843′N latitude and 108° 24.830′E longitude. It is defined at the base of a silty mudstone layer 52.8 m above the base of the Kaili Formation in the Wuliu-Zengjiayan section, coinciding with the first appearance of the cosmopolitan oryctocephalid trilobite Oryctocephalus indicus (base of the O. indicus Zone). Secondary global markers at or near the base of the series and stage include the peak of a rather large negative carbon isotopic excursion (ROECE excursion), the simultaneous appearance of many acanthomorphic acritarch forms, a transgressive phase of a major eustatic event, and the last appearance of intercontinental polymerid trilobites, either Bathynotus or Ovatoryctocara. Faunal turnovers close to the base of the Miaolingian Series and Wuliuan Stage have been recognized as being at the base of the Oryctocephalus indicus Zone of Amgan Stage in Siberia, the Delamaran Stage in Laurentia, the Oryctocephalus indicus Zone in the Indian Himalaya and North Greenland, near the base of the Delamaran Stage in Australia, and within the Eccaparadocides sdzuyi Zone in Iberia and the Ornamentaspis frequens Zone in Morocco.

Morphology and ontogeny of the eodiscoid trilobite Pagetia vinusta from the Cambrian (Miaolingian) of South China

The ontogenetic series of the eodiscoid trilobite Pagetia vinusta is first documented, from the crack-out specimens including numerous articulated individuals and many disarticulated sclerites from the Cambrian (Wuliuan) Kaili Formation, Guizhou, southwestern China. Better descriptions of morphological changes during growth are presented, especially the large spine on the glabella and sixth axial pygidial segment, as well as the prominent pygidial larval notch in meraspid development which became progressively less distinct and disappeared in holaspides. An ontogenetic series is established based on the immature and mature exoskeletons from the protaspid to holaspid period. Two substages can be differentiated in the protaspides. Two holaspid instars are recognized with a new pygidial segment added, indicating that the start of the holaspid phase preceded the onset of the epimorphic phase and, accordingly, its developmental mode is attributed to the protarthrous pattern. On this basis, due to the broad palaeogeographic distribution of Pagetia, its valid species are also thoroughly examined and discussed.

Paleoecological Significance of Complex Fossil Associations of the Eldonioid Pararotadiscus guizhouensis with other Faunal Members of the Kaili Biota (Stage 5, Cambrian, South China)

AbstractThe planktonic medusiform taxon Pararotadiscus guizhouensis (Zhao and Zhu, 1994) is one of the most abundant components of the Kaili Biota. Many specimens are in direct association with other taxa, including trilobites, brachiopods, hyolithids, echinoderms, and algae, as well as the trace fossil Gordia. Four types of interrelationships between P. guizhouensis and associated fossils are recognized: symbiosis, co-burial, attachment of benthic taxa on P. guizhouensis carcasses, and scavenging of P. guizhouensis carcasses. These associations of P. guizhouensis within the Kaili Biota are unique among occurrences of medusiform fossils in Burgess Shale-type biotas worldwide and provide important insights concerning ecological complexity in the Kaili Biota and in Cambrian marine communities in general.

A new macroalgal assemblage from the Xiaoshiba Biota (Cambrian Series 2, Stage 3) of southern China

Exquisitely preserved Burgess Shale-type fossils from the Xiaoshiba Lagerstätte in the Cambrian (Series 2) Hongjingshao Formation of southern China provide remarkable perspective on early metazoans but have never been reported with plants. Here we first recognize a new assemblage of highly mineralized macroalgae from this biota. Based on morphological differences, there are three new genera and four new species identified: Doulia rara gen. et sp. nov., Eolaminaria simigladiola sp. nov., Singulariphyca ramosa gen. et sp. nov. and Rugophyca longa gen. et sp. nov. Relative to the other three species, S. ramosa is widely distributed among the beds, which may indicate a dominat species in this community. This new discovery fills part of the long gap in the detailed record of macroalgae between the Chengjiang Biota and the Kaili Biota, representing a localized macroalgal flourish at the end of Cambrian Stage 3. The assemblage that shows morphological characters similar to some macroalgae found in the Precambrian and primitive to those of the Cambrian Stage 5 lays the basis for revealing the evolutionary biology of early macroalgae and understanding the Precambrian-Cambrian transition questions. Taphonomic study of this fossiliferous bed indicates that some well-preserved macroalgae are preserved within their original habitats. Through analyzing the depositional environments of the known Cambrian macroalgae, we suggest that macroalgae tend to be preserved in relatively deep marine environments with less disturbance.

Eldonioids with associated trace fossils from the lower Cambrian Emu Bay Shale Konservat-Lagerstätte of South Australia

AbstractRare specimens of eldonioids recovered from the lower Cambrian (Series 2, Stage 4) Emu Bay Shale (EBS) Konservat-Lagerstätte represent the first record of the group for the Cambrian of East Gondwana. The disc-shaped body of the EBS taxon bears fine concentric corrugations on the dorsal surface and, ventrally, a series of internal lobes that have primary and secondary bifurcations, as well as a coiled sac. It appears to be most similar toRotadiscusandPararotadiscusof the Cambrian Chengjiang and Kaili biotas of South China, respectively. While the structure of the internal lobes would indicate that this occurrence in the EBS represents a new taxon within the Rotadiscidae, lack of detail regarding the precise number of internal lobes and the condition of the circumoral tentacles warrants a more conservative approach in leaving the genus and species under open nomenclature. The EBS specimens also host trace fossils, including the remains of a burrow, which are generally lacking in the body-fossil-bearing layers of the Konservat-Lagerstätte interval. These traces appear to have been made by small organisms and are similar to traces associated with the discs ofPararotadiscus guizhouensis(Zhao and Zhu, 1994) from the Kaili Biota. The available taphonomic, paleoenvironmental, and ichnological evidence indicates that the EBS eldonioids are most likely vagrants that were transported or settled into the ‘preservational trap’ and subsequently exposed on the substrate for a brief period before burial, thereby allowing organisms to exploit their carcasses for nutrients or other purposes.

RETRACTION—Eldonioids with associated trace fossils from the lower Cambrian Emu Bay Shale Konservat-Lagerstätte of South Australia

Rare specimens of eldonioids recovered from the lower Cambrian (Series 2, Stage 4) Emu Bay Shale (EBS) Konservat-Lagerstatte represent the first record of the group for the Cambrian of East Gondwana. The disc-shaped body of the EBS taxon bears fine concentric corrugations on the dorsal surface and, ventrally, a series of internal lobes that have primary and secondary bifurcations, as well as a coiled sac. It appears to be most similar to Rotadiscus and Pararotadiscus of the Cambrian Chengjiang and Kaili biotas of South China, respectively. While the structure of the internal lobes would indicate that this occurrence in the EBS represents a new taxon within the Rotadiscidae, lack of detail regarding the precise number of internal lobes and the condition of the circumoral tentacles warrants a more conservative approach in leaving the genus and species under open nomenclature. The EBS specimens also host trace fossils, including the remains of a burrow, which are generally lacking in the body-fossilbearing layers of the Konservat-Lagerstatte interval. These traces appear to have been made by small organisms and are similar to traces associated with the discs of Pararotadiscus guizhouensis (Zhao and Zhu, 1994) from the Kaili Biota. The available taphonomic, paleoenvironmental, and ichnological evidence indicates that the EBS eldonioids are most likely vagrants that were transported or settled into the ‘preservational trap’ and subsequently exposed on the substrate for a brief period before burial, thereby allowing organisms to exploit their carcasses for nutrients or other purposes.

RETRACTED—Eldonioids with associated trace fossils from the lower Cambrian Emu Bay Shale Konservat-Lagerstätte of South Australia

AbstractRare specimens of eldonioids recovered from the lower Cambrian (Series 2, Stage 4) Emu Bay Shale (EBS) Konservat-Lagerstätte represent the first record of the group for the Cambrian of East Gondwana. The disc-shaped body of the EBS taxon bears fine concentric corrugations on the dorsal surface and, ventrally, a series of internal lobes that have primary and secondary bifurcations, as well as a coiled sac. It appears to be most similar toRotadiscusandPararotadiscusof the Cambrian Chengjiang and Kaili biotas of South China, respectively. While the structure of the internal lobes would indicate that this occurrence in the EBS represents a new taxon within the Rotadiscidae, lack of detail regarding the precise number of internal lobes and the condition of the circumoral tentacles warrants a more conservative approach in leaving the genus and species under open nomenclature. The EBS specimens also host trace fossils, including the remains of a burrow, which are generally lacking in the body-fossil-bearing layers of the Konservat-Lagerstätte interval. These traces appear to have been made by small organisms and are similar to traces associated with the discs ofPararotadiscus guizhouensisZhao and Zhu, 1994 from the Kaili Biota. The available taphonomic, paleoenvironmental, and ichnological evidence indicates that the EBS eldonioids are most likely vagrants that were transported or settled into the ‘preservational trap’ and subsequently exposed on the substrate for a brief period before burial, thereby allowing organisms to exploit their carcasses for nutrients or other purposes.

Additional trilobite fauna from the basal part of the Cambrian Series 3, Stage 5, Kunzam La (=Parahio) Formation, Parahio Valley, Spiti (Northwest Himalaya), India and its biostratigraphic significance

Additional Cambrian Series 3, Stage 5, trilobite fauna comprising Peronopsis sp., Eosoptychoparia cf. Spinosa Gaotanaspis cf. pingzhaiensis and Gaotanaspis cf. transversa have been recorded just immediately above the known Oryctocephalus indicus biozone (Cambrian Series 3, Stage 5) in the Parahio valley section (Spiti region). The FAD of Peronopsis and LAD of Gaotanaspis are used to establish a Peronopsis–Gaotanaspis concurrent biozone immediately above the Oryctocephalus indicus biozone. The first records of Gaotanaspis cf. pingzhaiensis and G. transversa from the Cambrian of Spiti region and the other faunal elements are correlated with the Peronopsis taijiangensis biozone of the Kaili Formation (South China). The stratigraphic thickness from the base of the O. indicus biozone to the top of the Peronopsis–Gaotanaspis concurrent biozone in the Kunzam La (=Parahio) Formation and its comparison to the Kaili Formation (South China) indicate a possible stratigraphic condensation in the basal part of the Cambrian Series 3, Stage 5 of the Parahio valley (Spiti). Sedimentological and sequence stratigraphic analysis supports this contention.

Siliceous spicules in a vauxiid sponge (Demospongia) from the Kaili Biota(Cambrian Stage 5), Guizhou, South China

Fossils of the sponge Angulosuspongia sinensis from calcareous mudstones of the middle and upper part of the Kaili Formation (Cambrian Stage 5) in the Jianhe area of Guizhou province, South China, exhibit an apparently reticulate pattern, characteristic of the Vauxiidae. Energy Dispersive X-Ray Spectrometry (EDS) and Raman spectroscopy analysis indicate the presence of silica in the skeletal elements of these fossils, suggesting that this taxon possessed a skeleton comprised of spicules. This is the first confirmation of siliceous skeletal elements in fossils of the family Vauxiidae, and it lends support to the hypothesis that some early demosponges possessed biomineralized siliceous skeletons, which were subsequently lost and replaced by spongin later in the evolutionary history of this lineage. The new materials provide critical insight into the phylogeny and evolution of biomineralization in the Demosopongiae.

A new vauxiid sponge from the Kaili Biota (Cambrian Stage 5), Guizhou, South China

AbstractThe skeleton of a new vauxiid sponge (Order Verongida),Angulosuspongia sinensisgen. et sp. nov., described on the basis of material from calcareous mudstones of the Kaili Formation (Cambrian Stage 5), Jianhe area, Guizhou, South China, is composed of two layers of fused spicules outlining hexagonal or polygonal openings. These vauxiid remains are the first reported from outside Laurentia, and represent only the second genus attributed to the family. Its age is close to but still slightly older than the Burgess Shale Biota, and it appears to be a primitive relative of other members of the Vauxiidae. The morphological differences between Chinese and Laurentian vauxiid sponges may be a result of vicariance. These specimens not only extend the geographic distribution of vauxiids, but also help to fill a chronostratigraphical gap between North Greenland and North American material and provide additional evidence for understanding the evolutionary history of the Demospongiae.

New Localities and Palaeoscolecid Worms from the Cambrian (Stage 4, Series 2) Guanshan Biota in Kunming, Yunnan, South China

AbstractThe Guanshan Biota from the Cambrian Stage 4 Wulongqing Formation is a typical Burgess‐shale type Lagerstätte that had witnessed the Cambrian explosion. Here we report two new localities of the Guanshan Biota, which is located at Baimei village, south of Kunming and Xinglong village, Wuding County, Yunnan Province respectively. Both localities produce soft‐body fossils and several new taxa, e.g. a new species of palaeoscolecidans (Palaeoscolex xinglongensis sp. nov.) reported herein. The comparative study of the new species with similar form not only indicates that there is a diversification of palaeoscolecid species in Guanshan Biota, but also strengthens the ties between the older Chengjiang Biota and the younger Kaili Biota (and also the coeval Burgess Shale community). Three paleoecological features, including high diversity, little disparity and richness of palaeoscolecid worms, are summarized as a case study to represent the differences between Guanshan and Chengjiang Biota.

The macroalga Bosworthia from the Cambrian Burgess Shale and Kaili biotas of North America and China

A comprehensive restudy of all material assigned in previous reports to the noncalcified macroalgal genus Bosworthia Walcott from the Burgess Shale Formation (Cambrian Stage 5) of western Canada and the slightly older Kaili Formation of South China, together with investigation of previously unpublished material, indicates important morphological differences between the two species heretofore included within the genus. On the basis of these differences, B. gyges is removed from the genus and assigned to Walcottophycus gen. nov. Most specimens previously assigned to Bosworthia from the Cambrian of China, including those assigned to B. simulans Walcott, are transferred to W. gyges, and it is concluded that Bosworthia remains unknown in China. Morphological details for this material when evaluated in the context of molecular clock studies and other fossil macroalgae indicate that B. simulans may belong to the extant red algal subclass Rhodymeniophycidae (Florideophyceae) and indicate that W. gyges may be an early form of bryopsidalean alga within the Chlorophyta.

A fresh look at Nisusia Walcott, 1905 from the Cambrian Kaili Formation in Guizhou

NisusiaWalcott, 1905 is an early genus of kutorginid brachiopod of the Subphylum Rhynchonelliformea. Originating in the Cambrian Series 2 and becoming extinct in the late Cambrian Series 3, Nisusia existed for a relatively short period of geologic time, and is a brachiopod genus that exhibited a slow rate of morphological evolution. This paper details the brachiopod Nisusia from the middle Cambrian Kaili Konservat-Lagerstätte. Nisusia, in terms of abundance, is one of the most important brachiopods from the Kaili Biota. Two Nisusia species from the Kaili Formation of the Cambrian Series 2–3 in the eastern part of Guizhou Province are described, Nisusia granosa and Nisusia guizhouensis n. sp. This study will give valuable insights into the morphological variability of Nisusia species, and provides new details on the composition of the brachiopod community in the Kaili Biota.

Fossil priapulid Ottoia from the Kaili biota (Cambrian Series 3) of South China

The fossil priapulid Ottoia recovered from the Kaili biota, Cambrian Series 3 and Stage 5 of South China, is the first reported occurrence of the genus outside the Cambrian of Laurentia. A total of 22 specimens are described as Ottoia guizhouensis sp. nov. The new species is distinguished from other Cambrian priapulids, including the type species of Ottoia, O. prolifica Walcott, 1911 from the Burgess Shale, by the introvert that lacks a swollen base and bears a smaller number of longitudinal rows of hooks, and a more elongated trunk with more closely spaced annulations. Anatomically, a probable gizzard, a pair of posterior retractor muscles and muscle fibres of the gut wall are also observed in O. guizhouensis. The presence of the paired retractor muscles can be considered an indication of bilateral symmetry. Gut contents in O. guizhouensis suggest that this animal had an occasional deposit-feeding habit. Specimens buried in life position suggest that Ottoia may have burrowed and wriggled in all directions within the sediment and did not merely make U-shaped burrows. The new occurrence of Ottoia from the Kaili biota sheds new light on the morphology, anatomy and palaeogeographical distribution of this well-known genus, as well as providing new information on the early evolution of priapulids.

Restudy of Ovatoryctocara Tchernysheva, 1962 from the Kaili Formation, Jianhe County, Guizhou, South China

The First Appearance Datum (FAD) of the oryctocephalid trilobite Ovatoryctocara granulata Tchernysheva, 1962 is one of the candidates for establishing the base of the Cambrian Series 3, Stage 5. However some records of this taxon in China and elsewhere are doubtful and in need of review. Ovatoryctocara cf. granulata and Ovatoryctocara sp., previously described from the lower part of the Kaili Formation, China are transferred herein to Ovatoryctocara sinensis sp. nov., which shows significant morphological differences with type specimens of O. granulata. All Chinese specimens of Ovatoryctocara are therefore transferred to O. sinensis sp. nov. As consequence, the former trilobite Zone Bathynotus kueichouensis-Ovatoryctocara cf. guanulata is renamed the Bathynotus kueichouensis-Ovatoryctocara sinensis Assemblage Zone. O. granulata from Newfoundland also exhibits large differences in morphology with type specimens of O. granulata from Siberia. It is concluded that O. granulata does not occur in China but is restricted to Siberia and North Greenland. Hence, O. granulata is not suitable for defining the Cambrian Series 2–3 boundary, as previously suggested.