A lower Cambrian fauna of skeletal fossils from the Emyaksin Formation, northern Siberia

Kouchinsky, Artem; Bengtson, Stefan; Clausen, Sébastien; Vendrasco, Michael J.

doi:10.4202/app.2012.0004

Cited by 42 publications

(104 citation statements)

References 112 publications

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“…Discoidal sclerites of Tarimspira plana are discovered on the Zhenba-Fangxian Block. Morphologically similar sclerites have been reported from Hubei, Zhejiang (He and Yu, 1992;Steiner et al, 2003), Tarim (Yue and Gao, 1992), Anabar and Olenek uplifts of Siberia (Müller et al, 1995;Kouchinsky et al, 2014). Due to the fact that Fengzuella zhejiangensis He and Yu, 1992 is a homonym of the Ordovician brachiopod Fengzuella zhejiangensis Han, 1980 (Li andHan, 1980) this name is invalid.…”

Section: Systematic Paleontologymentioning

confidence: 84%

“…SSFs have been widely applied as a biostratigraphic tool in the early Cambrian (Rozanov and Missarzhevsky, 1966;Qian, 1978;Missarzhevsky and Mambetov, 1981;Qian, 1989;Qian and Bengtson, 1989;Bengtson et al, 1990;Elicki and Schneider, 1992;Gondwana Research xxx (2014) xxx-xxx Esakova and Zhegallo, 1996;Gravestock et al, 2001;Steiner et al, 2003;Steiner et al, 2004;Skovsted, 2006;Steiner et al, 2007;Shabanov et al, 2008;Varlamov et al, 2008;Kouchinsky et al, 2014;Yang et al, 2014a). It has been argued that many elements of SSFs were endemic and facies-dependent (Landing, 1992;Mount and Signor, 1992;Landing et al, 2013a).…”

Section: Introductionmentioning

confidence: 97%

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Early Cambrian palaeobiogeography of the Zhenba–Fangxian Block (South China): Independent terrane or part of the Yangtze Platform?

2015

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Section: Systematic Paleontologymentioning

confidence: 84%

Section: Introductionmentioning

confidence: 97%

Early Cambrian palaeobiogeography of the Zhenba–Fangxian Block (South China): Independent terrane or part of the Yangtze Platform?

2015

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“…However, the internal structure and related surface lineations in Rhombocorniculum compare favourably with the equivalently fine-scale longitudinal lineations observed in Hallucigenia spines from the Burgess Shale and as SCFs (figures 1f,g and 2b), and some specimens additionally exhibit external basal constrictions (e.g. [21], plate 10.1; [24]), which conceivably correspond to the nested cone structure of H. sparsa and related SCFs. Assemblages of Rhombocorniculum often include both right-and lefthanded variants, and include forms that vary considerably in their aspect ratio, degree of flattening and curvature [21].…”

Section: 'Small Shelly' Hallucigeniid Spinesmentioning

confidence: 99%

“…Like the spines of Hallucigenia, Rhombocorniculum exhibits a non-flaring base, a central longitudinal cavity and a perturbed cancellate ornament [23]. Its distinctive microstructure of longitudinal, edge-parallel or slightly inclined canals has been interpreted as indicating accretionary growth, either internally (in the manner of protoconodonts) [23] or by microvilli (as in annelids) [24]. However, the internal structure and related surface lineations in Rhombocorniculum compare favourably with the equivalently fine-scale longitudinal lineations observed in Hallucigenia spines from the Burgess Shale and as SCFs (figures 1f,g and 2b), and some specimens additionally exhibit external basal constrictions (e.g.…”

Section: 'Small Shelly' Hallucigeniid Spinesmentioning

confidence: 99%

Beyond the Burgess Shale: Cambrian microfossils track the rise and fall of hallucigeniid lobopodians

2013

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Burgess Shale-type deposits are renowned for their exquisite preservation of soft-bodied organisms, representing a range of animal body plans that evolved during the Cambrian 'explosion'. However, the rarity of these fossil deposits makes it difficult to reconstruct the broader-scale distributions of their constituent organisms. By contrast, microscopic skeletal elements represent an extensive chronicle of early animal evolution-but are difficult to interpret in the absence of corresponding whole-body fossils. Here, we provide new observations on the dorsal spines of the Cambrian lobopodian (panarthropod) worm Hallucigenia sparsa from the Burgess Shale (Cambrian Series 3, Stage 5). These exhibit a distinctive scaly microstructure and layered (cone-in-cone) construction that together identify a hitherto enigmatic suite of carbonaceous and phosphatic Cambrian microfossils-including material attributed to Mongolitubulus, Rushtonites and Rhombocorniculum-as spines of Hallucigenia-type lobopodians. Hallucigeniids are thus revealed as an important and widespread component of disparate Cambrian communities from late in the Terreneuvian (Cambrian Stage 2) through the 'middle' Cambrian (Series 3); their apparent decline in the latest Cambrian may be partly taphonomic. The cone-in-cone construction of hallucigeniid sclerites is shared with the sclerotized cuticular structures ( jaws and claws) in modern onychophorans. More generally, our results emphasize the reciprocal importance and complementary roles of Burgess Shale-type fossils and isolated microfossils in documenting early animal evolution.

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“…) and may represent a single species probably conspecific with the Swedish form (Kouchinsky et al . ). A specimen from the Atdabanian Parara Limestone of South Australia that fits such morphology was attributed to Byronia by Bengtson et al .…”

Section: Cambrian Roots Of Sphenothallusmentioning

confidence: 97%

The origin of tetraradial symmetry in cnidarians

Dzik

Baliński

Sun

2017

LET

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Serially arranged sets of eight septa‐like structures occur in the basal part of phosphatic tubes of Sphenothallus from the early Ordovician (early Floian) Fenxiang Formation in Hubei Province of China. They are similar in shape, location and number, to cusps in chitinous tubes of extant coronate scyphozoan polyps, which supports the widely accepted cnidarian affinity of this problematic fossil. However, unlike the recent Medusozoa, the tubes of Sphenothallus are flattened at later stages of development, showing biradial symmetry. Moreover, the septa (cusps) in Sphenothallus are obliquely arranged, which introduces a bilateral component to the tube symmetry. This makes Sphenothallus similar to the Early Cambrian Paiutitubulites, having similar septa but with even more apparent bilateral disposition. Biradial symmetry also characterizes the Early Cambrian tubular fossil Hexaconularia, showing a similarity to the conulariids. However, instead of being strictly tetraradial like conulariids, Hexaconularia shows hexaradial symmetry superimposed on the biradial one. A conulariid with a smooth test showing signs of the ‘origami’ plicated closure of the aperture found in the Fenxiang Formation supports the idea that tetraradial symmetry of conulariids resulted from geometrical constrains connected with this kind of closure. Its minute basal attachment surface makes it likely that the holdfasts characterizing Sphenothallus and advanced conulariids are secondary features. This concurs with the lack of any such holdfast in the earliest Cambrian Torellella, as well as in the possibly related Olivooides and Quadrapyrgites. Bilaterally arranged internal structures in polyps representing probably the oldest medusozoans support the suggestions based on developmental evidence that the ancestor of cnidarians also was a bilaterally symmetrical animal. This is one more example of fossil data that strictly fit the molecular phylogenetic evidence but not necessarily morphology‐based zoological interpretations.

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A lower Cambrian fauna of skeletal fossils from the Emyaksin Formation, northern Siberia

Cited by 42 publications

References 112 publications

Early Cambrian palaeobiogeography of the Zhenba–Fangxian Block (South China): Independent terrane or part of the Yangtze Platform?

Early Cambrian palaeobiogeography of the Zhenba–Fangxian Block (South China): Independent terrane or part of the Yangtze Platform?

Beyond the Burgess Shale: Cambrian microfossils track the rise and fall of hallucigeniid lobopodians

The origin of tetraradial symmetry in cnidarians

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