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24 ADVANCES IN PALAEOICHTHYOLOGY well as greatly extending the area from which these animals are known. The collection is currently being described by two of us (Elliott and Mark-Kurik) and includes some of the same species that occur in the Baltic (Elliott et al. 2003), thus allowing the development of a correlation scheme (Obruchev and Mark-Kurik 1968). Included within the collection are plate fragments from the Late Devonian Clastic Wedge that are extremely thick and that do not have a surface ornament of dentine tubercles. This feature is otherwise only described in the aberrant psammosteid Obruchevia (Obruchev 1936) from the Lovat´ River, northwest Russia. In this paper we describe the new Canadian material and also add to the knowledge of Obruchevia by the description of additional material from the collections of the Latvian Natural History Museum, Riga, and the Palaeontological Institute, Russian Academy of Sciences, Moscow. Stratigraphy Most of the Canadian Arctic obrucheviid material in this report was collected from a single site near Okse Bay on southern Ellesmere Island (Fig. 1). The site, designated as field site NV2K11, is within the lower to middle part of the Nordstrand Point Formation exposed on the northern limb of the Schei Syncline. The fossil site is located within 2km of the type section of the Nordstrand Point Formation as designated by Embry and Klovan (1976). Most of the Nordstrand Point Formation is middle Frasnian in age based on palynomorph samples, although the upper 100 to 200 meters of the 675-meter-thick type section are late Frasnian (Embry and Klovan 1976). The Nordstrand Point Formation is the uppermost unit of the Okse Bay Group. On southern Ellesmere Island the Okse Bay Group is a 3000-meter-thick succession of fluvial sediments derived from tectonic highlands to the east that fed several fluvial systems prograding generally to the southwest (Mayr et al. 1994). The fossiliferous horizon at the NV2K11 site is a dark, carbonaceous siltstone. The obrucheviid and other fossil material is abundant in the fissile siltstone as well as an underlying ironstone layer. The total thickness of this fossiliferous zone is 120 to 150 mm. The sediments suggest a low energy overbank depositional setting rich in organic material. Fossil plant material occurs as large compressed stems and as three-dimensional stems up to 100 mm in diameter. Associated vertebrate fauna from the NV2K11 site includes Psammosteus sp., Bothriolepis sp., and Holoptychius sp. An additional fragment of obrucheviid plate was recovered in 1999 from the sequence of Late Devonian clastic sediments near the southern coast of Ile Vanier (Bathurst Island Group). This locality is designated NV9918, and is 400 km west of the NV2K11 site (Fig. 1). The stratigraphic position of the NV9918 site is problematic, although currently mapped as within the Cape Fortune Member of the Parry Islands Formation by Harrison and de Freitas (1998). The Cape Fortune Formation is mainly early Famennian in age (Embry and Klovan 1976). Harrison’s mapping was based on lithostratigraphic markers; however, the obrucheviid specimen, as well as psammosteid material from other localities on Ile Vanier, suggest that it is in error. It is more likely that the psammosteids on Ile Vanier are from the upper part of the Beverly Inlet Formation and therefore Frasnian in age. The Beverly Inlet Formation is considered to be distal facies
D.K. Elliott, E. Mark-Kurik, E.B. Daeschler. A revision of Obruchevia 25 Fig. 1. Map of the central Arctic Islands showing the fossil locality and the Late Devonian stratigraphic section on southern Ellesmere Island.
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Page 5 and 6: Contents Ervīns Lukševičs and Ģ
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Page 9 and 10: Ervīns Lukševičs, Ģirts Stinkul
Page 15 and 16: Olga Afanassieva. Microrelief on th
Page 23: D.K. Elliott, E. Mark-Kurik, E.B. D
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Page 47 and 48: C.G.Miller, T. Marss, H. Blom. New
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Page 59 and 60: H.-P. Schultze, T. Marss. Revisitin
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H.-P. Schultze, T. Marss. Revisitin
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H.-P. Schultze, T. Marss. Revisitin
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ACTA UNIVERSITATIS LATVIENSIS, 2004
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O.A. Lebedev. A new tetrapod from R
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E. Lukševičs, I. Zupiņš. Sedime
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J. Valiukevičius. Silurian acantho
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Ž. Žigaite. New telodont from Tuv
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