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1
Content available Alleged cnidarian Sphenothallus in the Late Ordovician of Baltica, its mineral composition and microstructure
100%
Vinn O. , Kirsimae K.
Acta Palaeontologica Polonica
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2015
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tom 60
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nr 4
EN
Sphenothallus is a problematic fossil with possible cnidarian affinities. Two species of Sphenothallus, S. aff. longissimus and S. kukersianus, occur in the normal marine sediments of the Late Ordovician of Estonia. S. longissimus is more common than S. kukersianus and has a range from early Sandbian to middle Katian. Sphenothallus had a wide paleo-biogeographic distribution in the Late Ordovician. The tubes of Sphenothallus are composed of lamellae with a homogeneous microstructure. The homogeneous microstructure could represent a diagenetic fabric, based on the similarity to diagenetic structures in Torellella (Cnidaria?, Hyolithelminthes). Tubes of Sphenothallus have an apatitic composition, but one tube contains lamellae of diagenetic calcite within the apatitic structure. Sphenothallus presumably had originally biomineralized apatitic tubes. Different lattice parameters of the apatite indicate that biomineralization systems of phosphatic cnidarians Sphenothallus and Conularia sp. may have been different.
2
Content available A new microconchid tubeworm from the Artinskian (Lower Permian) of central Texas, USA
80%
Wilson M. A. , Vinn O. , Yancer T. E.
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nr 4
EN
Calcareous tubeworms are common in the Artinskian (Lower Permian) shale and limestone rocks of the Wichita−Albany Group in central Texas. In some units they form small reefs of budding tubes spreading outward from a common origin. These tubular fossils have been traditionally referred to as serpulids, but here we identify them as microconchids (Helicoconchus elongatus gen. et sp. nov.) These microconchids are unusual because of their greatly elongated impunctate tubes with centrally pitted diaphragms. They also show two types of budding: lateral with small daughter tubes that begin as small coils, and binary fission that produced two daughter tubes of equal diameters. These microconchids flourished in shallow marine environments with a fauna dominated by mollusks, echinoids, and foraminifera.
3
Content available Crinoids from the Silurian of Western Estonia
80%
Ausich W. I. , Wilson M. A. , Vinn O.
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nr 3
EN
The Silurian crinoids of Estonia are re−evaluated based on new collections and museum holdings. Nineteen species−level crinoid taxa are now recognized. All crinoid names applied to Estonian Silurian crinoids during the middle 19th century are disregarded. Especially significant is the fauna reported herein from the Pridoli because coeval crinoids are very poorly known from the Baltic region and elsewhere. One new genus and four new species are described from Estonia, namely Calceocrinus balticensis sp. nov., Desmidocrinus laevigatus sp. nov., Eucalyptocrinites tumidus sp. nov., and Saaremaacrinus estoniensis gen. et sp. nov.
4
Content available Sclerobionts on organic substrates from the Late Paleocene Chehel-Kaman Formation, Kopet-Dagh Basin, NE Iran
80%
Salahi A. , El Hedeny M. , Vinn O. , Rashwan M.
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tom Vol. 88, No. 3
291--301
EN
Molluscs (oysters and gastropods) of the Late Paleocene Chehel-Kaman Formation, Kopet-Dagh Basin NE Iran were significantly colonized by sclerobionts. The largest area of the shells studied is covered by various borings. The diversity of macro-bioeroding ichnotaxa is rather high, including Gastrochaenolites Leymerie 1842; Maeandropolydora Voigt, 1965; Trypanites Mägdefrau, 1932; Talpina von Hagenow, 1840, and possibly Entobia Bronn, 1837. Some slightly conical borings penetrating the shells could belong to predatory tracemakers of Oichnus Bromley, 1981. Encrusters include calcareous polychaetes, cyclostome and cheilostome bryozoans, foraminifera and oysters. Calcareous sabellids [i.e. Glomerula serpentina (Goldfuss, 1831)] and serpulids are equally common sclerobionts in the association. Bryozoans cover a slightly larger area of the substrate than the calcareous polychaetes, while encrusting oysters are subordinate. The majority of fossils in the hard-substrate community studied belong to suspension feeders. Sclerobionts are typical of the shallow-marine environment, commonly in warm water. The present study is the first attempt to record the occurrence and diversity of epi- and endobionts in the organic substrates, present in the topmost part of the Late Paleocene Chehel-Kaman Formation, Kopet-Dagh Basin, NE Iran.
5
Content available Middle and Late Jurassic tube-dwelling polychaetes from the Polish Basin: diversity, palaeoecology and comparisons with other assemblages
80%
Slowinski J. , Vinn O. , Jager M. , Zaton M.
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tom 67
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nr 4
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