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1
Content available remote Protodus jexi Woodward, 1892 (Chondrichthyes), from the Lower Devonian Campbellton Formation, New Brunswick, Canada
Turner S., Miller R.
Acta Geologica Polonica
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2008
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Vol. 58, no. 2
133-145
EN
Protodus jexi from the early Emsian 'Atholville beds', Campbellton Formation between Atholville and Campbellton, northern New Brunswick, Canada, is redescribed from material studied by R. H. Traquair and new specimens. Protodus is a valid monotypic genus with rows of shark-like serrated teeth. The taxon is based solely on teeth, some of which are associated. The teeth have monocuspid crowns with a thin enameloid layer and distinctive labial depressions or grooves, and large subrectangular to D-shaped cladodont-like bases some laterally and downwards extended. Crown histology is orthodentine merging down into the osteodentine of the base. A possible relationship with cladodont-bearing sharks is mooted and Protodus and other putative late Silurian to early Devonian chondrichthyan teeth are referred to a redefined family Protodontidae WOODWARD.
2
Content available Geological setting of the Milejowice-Janowice diabase intrusion: insights into post-Caledonian magmatism in the Holy Cross Mts., Poland
Kowalczewski Z.
Geological Quarterly
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2004
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Vol. 48, No 2
135--146
EN
Near Milejowice and Janowice in the eastern part of the Łysogóry Unit of the Holy Cross Mts., Poland, a SW-NE trending diabase has been identified intruding Lower Palaeozoic strata. This intrusion causes amagnetic anomaly, with delta T values of 48-112 gamma. It is orientated perpendicular to the regional strike. Boreholes encountered one to three component dykes 2.0 to more than 10.0 m thick inclined at 75-90 degrees Celsius, generally towards the east. They are hydrothermally altered and affected by surface weathering. The intrusion is located along two independent transverse faults, "skipping" from one to another irrespective of their strike. The intrusive zone is strongly tectonically disturbed, S-curved and disrupted by faults into segments and sub-segments. Most of the diabases are slicken-sided, and locally cataclased and mylonitized. The Milejowice-Janowice diabases probably formed in the Early Devonian, i.e. late Lochkovian-early Pragian, as post-tectonic igneous rocks belonging to within-plate, continental basalts according to Krzemiński (2004). Their origin may be referred tomagmatism triggered by the extension of the Baltica passivemargin during the final Late Silurian-Early Devonian phase of its collision with eastern Avalonia. A complex and at least two-phase development ofmagmatism in the Holy Cross Mts. is envisaged.
3
Content available remote New Late Silurian to Middle Devonian acanthodians of the Timan-Pechora region
Valiukevicius J.
Acta Geologica Polonica
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2003
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Vol. 53, nr 3
209-245
EN
New Pridoli to Eifelian acanthodian scales from various structural units of the Timan-Pechora region are described. Among 15 new species and 1 new genus, there are: 10 new species of nostolepids, common members of most of the biostratigraphic associations, the monospecific genus Monospina gen. nov., a single new species of Cheiracanthoides (all Climatiida), Diplacanthus pechorensis sp. nov. (Diplacanthida), and two new species of Gomphonchus (Ischnacanthida). Besides morphologic descriptions the taxa are also characterised histologically. Acanthodian taxa with scale crowns and bases composed of cellular bone, or very similar tissue, proposed as a primitive feature in their evolution, are reported for the first time.
4
Content available remote Lower Devonian conodonts from the Karlik Valley and Na Branzovech sections in the Barrandian area, Czech Republic, and their significance for Pragian conodont zonation
Slavik L.
Acta Geologica Polonica
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2001
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Vol. 51, nr 3
253-271
EN
Two Early Devonian sections used for this study display a markedly different facies development and lie opposite limbs of the central Barrandian synform, in the stratotype area of the Pragian Stage. The present biostratigraphical information based on 18 species with a total of 350 conodont specimens is mostly related to the late Lochkovian and early Pragian, whilst the remaining parts of the Pragian involve mostly long-range conodont species. The late Lochkovian conodonts correspond to two zones eurekaensis and delta. The latest Lochkovian zone pesavis was found in the northwestern limb, but not on the opposite side. The absence of pesavis Zone in the south (Koneprusy) and, as it has been newly shown, in the south-east of the central Barrandian synform (Karlik Valley) suggests that a prominent lowstand sedimentary starvation affected much larger areas than only the tops of elevated ridges. The lower two thirds of the Pragian sequences can be zoned using two newly suggested conodont zones steinachensis and serratus, respectively, that are defined by the first and last occurrences of these taxa.The occurrence of Latericriodus steinachensis (AL-RAWI) eta morph. marks the lower third and the entry of Peleksygnathus serratus serratus JENTZSCH corresponds to the base of the middle third of the Pragian. The newly suggested stratigraphical applicability of these two species can effectively substitute the pre-existing sulcatus and kindlei subdivisions that have no zonal species representation in the stratotype area. The first occurrence of Latericriodus bilatericrescens bilatericrescens (ZIEGLER) seems to indicate the base of the Emsian in the Na Branzovech section. The entry of this taxon is connected with the black-shale Graptolite Event within the latest Dvorce-Prokop Limestone that is several beds higher than the levels usually considered for entry of a debatable taxon Polygnatus pireneae. The base of the Graptolite Event gives better chance for the correlation of the Pragian-Emsian boundary than any of the underlying levels. Evolution of the Barrandian conodont assemblages shows many parallels with those of Morocco and Carnic Alps.
5
Content available remote Tetanopsyrus lindoei gen. et sp. nov., an Early Devonian acanthodian from the Northwest Territories, Canada
Gagnier P., Hanke G., Wilson M.
Acta Geologica Polonica
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1999
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Vol. 49, no. 2
81-96
EN
An acanthodian, Tetanopsyrus lindoei gen. et sp. nov., is described. All specimens are from Lochkovian of northwestern Canada. The body is covered with unornamented, flat scales, with two finely noded dorsal spines, finely noded anal, pelvic and pectoral spines, a high scapulocoracoid, and toothless jawbones with large, flat, crushing surfaces. Tetanopsyrus lacks pectoral dermal plates and intermediate pre-pelvic fin spines. Tetanopsyrus is classified in the new family Tetanopsyridae, and possible relationships of the family to diplacanthids are discussed.
6
Content available remote Lagoonal to normal marine Late Silurian - Early Devonian ostracode assemblages of the Eurasian Arctic
Abusik A., Evdokimova I.
Acta Geologica Polonica
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1999
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Vol. 49, no. 2
133-143
EN
In the Eurasian Arctic the ostracode faunas indicate mostly normal marine environments during the Late Silurian. The Lower Devonian deposits are characterized by ostracode assemblages, which indicate the presence of marine outer shelf to lagoonal environments during the Early Devonian. The dynamics of their taxonomic diversity and some examples of the marine and lagoonal assemblages are shown. Correlation of facially mono- and heterogenous deposits is based on ostracode data
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