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Gonzalo Vidal [ 1943-1997 ]

100%

Bengtson S.

Acta Palaeontologica Polonica

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1997

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tom 42

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nr 2

2

The tube wall of Cambrian anabaritids

84%

Kouchinsky A., Bengtson S.

Acta Palaeontologica Polonica

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2002

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tom 47

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nr 3

Celestite/barite−replaced and phosphate−replicated tubes of Early Cambrian anabaritids from the northern part of the Siberian Platform (Anabar Shield) give new evidence on the wall−structure of these enigmatic fossils. The walls consist of fibres, interpreted as reflecting an original aragonitic fabric. Bundles of fibres are arranged in growth lamellae, and the latter form an angle of at least 45° with the inner tube wall. Where the outer tube surface projects into annular flanges, the lamellae have a chevron−like section due to the backwards deflection of the outer parts. Anabaritids are usually referred to the Cnidaria or left without systematic assignment, but earlier suggestions included affinity to the serpulid polychaetes. The chevron structure resembles that previously exclusively known from serpulids, but the presence of internal tooth−like structures in anabaritid tubes, perhaps compromising up−and−down movement through the tubes, continue to make a direct assignment to the Serpulida questionable.

3

The integument of Cambrian chancelloriids

84%

Bengtson S., Hou X.

Acta Palaeontologica Polonica

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2001

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tom 46

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nr 1

Details of the body surface of the chancelloriid Allonnia from the Lower Cambrian Chengjiang biota in southwestern China elucidate the nature of these enigmatic organisms. Rhombically arranged elements, about 30 x 60 ym, are interpreted as representing imbricating platelets, the distal ends of which projected as spinules from the body surface. Comparisons with other chancelloriids suggest that the flexible integument was continuous with the aragonitic sclerites that sit on the surface like cactus spines, and that both were formed by an epidermal epithelium secreting a continuous exo- and endocuticle. In the sclerites, the exocuticle was mineralized; the unmineralized endocuticle and cellular extensions from the epithelium filled the interior of the sclerites. In the flexible integument the epithelium was overlain by endocuticle and unmineralized exocuticle. This structure of soft integument and sclerites is at variance with proposals of poriferan or ascidian affinity of chancelloriids but in accord with a coeloscleritophoran model.

4

The problematic early Cambrian fossil Tumulduria incomperta represents the detached ventral interarea of a paterinid brachiopod

68%

Skovsted C. B., Kouchinsky A., Bengtson S., Holmer L. E.

Acta Palaeontologica Polonica

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2014

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tom 59

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nr 2

The organophosphatic early Cambrian (Terreneuvian, Cambrian Stage 2) fossil Tumulduria incomperta has been problematic ever since its original description in 1969. Comparison of abundant specimens from the Lower Cambrian of Siberia with co-occurring brachiopod valves show that T. incomperta represents the central portion of the ventral interarea of a paterinid brachiopod similar to Cryptotreta neguertchenensis, and that the domed central portion of typical Tumulduria specimens represents the ridge-like pseudodeltidium of the interarea.

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A new tannuolinid problematic from the lower Cambrian of the Sukharikha River in northern Siberia

68%

Kouchinsky A., Bengtson S., Murdock D. J. E.

Acta Palaeontologica Polonica

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2010

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tom 55

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nr 2

321-331

A new species of tannuolinid, Tannuolina pavlovi, is reported from the basal Krasnoporog Formation cropping out along the Sukharikha River at the northwestern margin of the Siberian Platform. The new material expands the geographic range of tannuolinids onto the Siberian Platform and extends their stratigraphic range into the basal Tommotian Stage of the traditional Lower Cambrian. The oldest appearance of tannuolinids in the fossil record is shown herein to have occurred as early as the oldest appearance of the linguliformean brachiopods, of which tannuolinids have been suggested to be a stem group. The sellate sclerites of T. pavlovi sp. nov. are different from those of the other known species of Tannuolina in the consistent absence of a pronounced sella and duplicature on the respective sides of sclerites, as well as in having regularly distributed large setal pores on the lateral edges. The mitral sclerites of T. pavlovi sp. nov. do not clearly show asymmetry of left and right forms, manifested in other species by the presence of the carina on the interior surface. Large pores aligned along the lateral margins of sellate sclerites regularly coalesce below the wall surface from an apically and an aperturally directed basal branch, forming a nearly right angle.

6

An early Cambrian fauna of skeletal fossils from the Emyaksin Formation, northern Siberia

68%

Kouchinsky A., Bengtson S., Clausen S., Vendrasco M. J.

Acta Palaeontologica Polonica

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2015

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tom 60

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nr 2

An assemblage of mineralised skeletal fossils containing molluscs, hyoliths, halkieriids, chancelloriids, tommotiids, lobopodians, paleoscolecids, bradoriids, echinoderms, anabaritids, hyolithelminths, hexactinnelid, and heteractinid sponges is described from the early Cambrian Emyaksin Formation exposed along the Malaya Kuonamka and Bol’shaya Kuonamka rivers, eastern flanks of the Anabar Uplift, northern Siberian Platform. The sampled succession is attributed to the Tommotian–Botoman Stages of Siberia and correlated with Stage 2 of Series 1–Stage 4 of Series 2 of the IUGS chronostratigraphical scheme for the Cambrian. Carbon isotope chemostratigraphy is applied herein for regional correlation. The fauna contains the earliest Siberian and probably global first appearances of lobopodians, paleoscolecids, and echinoderms, and includes elements in common with coeval faunas from Gondwana, Laurentia, and Baltica. For the first time from Siberia, the latest occurrence of anabaritids is documented herein from the Atdabanian Stage. Problematic calcium phosphatic sclerites of Fengzuella zhejiangensis have not been previously known from outside China. The sellate sclerites, Camenella garbowskae and mitral sclerites, C. kozlowskii are unified within one species, C. garbowskae. In addition to more common slender sclerites, Rhombocorniculum insolutum include broad calcium phosphatic sclerites. A number of fossils described herein demonstrate excellent preservation of fine details of skeletal microstructures. Based on new microstructural data, sclerites of Rhombocorniculum are interpreted as chaetae of the type occurring in annelids. A new mollusc Enigmaconus? pyramidalis Kouchinsky and Vendrasco sp. nov. and a hyolith Triplicatella papilio Kouchinsky sp. nov. are described.

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Phosphatised olenid trilobites and associated fauna from the Upper Cambrian of Vastergotland, Sweden

68%

Ahlberg P., Szaniawski H., Clarkson E. N. K., Bengtson S.

Acta Palaeontologica Polonica

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2005

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tom 50

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nr 3

Secondarily phosphatised olenid trilobites from organic−rich limestones (orsten) in the Furongian (Upper Cambrian) of Västergötland, south−central Sweden, are described and illustrated. All trilobites originate from the Peltura scarabaeoides Zone and were collected on the western slope of Kinnekulle. Only the dorsal exoskeletons have become secondarily phosphatised, and the ventral appendages are not preserved. Yet the material is otherwise remarkably well preserved and reveals the morphology of the olenid trilobites in greater detail than hitherto known. Species belonging to the genera Ctenopyge, Sphaerophthalmus, Parabolina, and Peltura are identified, and several juvenile specimens are present in the material. The material is disarticulated and fragmentary, and it has only been possible to identify a few specimens to species level. In addition to chaetognaths and conodonts, the trilobites are associated with pelmatozoan columnals, a possible camaroid, and fossils of uncertain affinities. These fossils, along with a probable conulariid fragment from the Peltura minor Zone, are also described and discussed. The presence of a benthic fauna of pelmatozoans, and possible conulariids and camaroids, indicates that at least parts of the Peltura zones were deposited during dysoxic rather than anoxic periods. Moreover, the sea floor must have been firm enough to allow colonisation by sessile organisms.

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Silicified and phosphatized Tianzhushania, spheroidal microfossil of possible animal origin from the Neoproterozoic of South China

68%

Yin C., Bengtson S., Yue Z.

Acta Palaeontologica Polonica

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2004

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tom 49

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nr 1

Comparative study of microfossils from two kinds of sediments: chert intercalations (studied in thin section) and phosphorite/phosphatic carbonate (in thin section and maceration), from the upper Neoproterozoic Doushantuo phosphorites in the Weng’an area, Guizhou Province, South China, shows that the phosphatized Megasphaera ornata and the chert−preserved Tianzhushania tuberifera should be regarded as representing the same taxon preserved by different mineralization processes. In phosphatized specimens the outer wall is often peeled off, exposing the ornamented middle wall. Some phosphatized specimens isolated from the rock matrix and specimens seen in thin sections of phosphorites show a partly preserved outer wall with spines, which can be compared to the thin−sectioned specimens from the chert beds. The small pits usually seen on the surface of the ornamented middle wall of phosphatized specimens correspond to the attachment spots of the spines in the outer wall. The presence of a spiny outer wall is a characteristic of Tianzhushania Yin and Li, 1978. Tianzhushania ornata (Xiao and Knoll, 2000) comb. nov. is here proposed as the valid name for the species. The proposed resting−egg nature of T. ornata, mainly based on the ornament type of the middle wall, cannot be excluded. The presence of a spiny outer wall, however, suggests that it is a pelagic rather than a benthic form.

Ograniczanie wyników

8 Acta Palaeontologica Polonica

8 Bengtson S.

4 Kouchinsky A.

1 Ahlberg P.

1 Clarkson E. N. K.

1 Clausen S.

1 Holmer L. E.

1 Hou X.

1 Murdock D. J. E.

1 Skovsted C. B.

1 Szaniawski H.

1 Vendrasco M. J.

1 Yin C.

1 Yue Z.

1 2015

1 2014

1 2010

1 2005

1 2004

1 2002

1 2001

1 1997

Gonzalo Vidal [ 1943-1997 ]

The tube wall of Cambrian anabaritids

The integument of Cambrian chancelloriids

The problematic early Cambrian fossil Tumulduria incomperta represents the detached ventral interarea of a paterinid brachiopod

A new tannuolinid problematic from the lower Cambrian of the Sukharikha River in northern Siberia

An early Cambrian fauna of skeletal fossils from the Emyaksin Formation, northern Siberia

Phosphatised olenid trilobites and associated fauna from the Upper Cambrian of Vastergotland, Sweden

Silicified and phosphatized Tianzhushania, spheroidal microfossil of possible animal origin from the Neoproterozoic of South China