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Conodonts of the Kashirian Regional Substage in the Upper Volga region are studied for the first time. A conodont assemblage established in a quarry section near the village of Fedyaikino on the Osuga River, allows the correlation of the dolomite series with interbeds of marls and clays (11.45 m) with the Kashirian Nara Formation assigned to the Neognathodus bothrops Zone. In the section near the village of Mozgovo on the Derzha River, limestones and dolomites with cherts (7 m) are attributed to the upper part of the Kashirian, to the Neognathodus medadultimus Zone, although Member C, unconformably overlying Member B, may be Podolskian. Conodont assemblages are typical of sections of the East European Platform. The deposition took place in an offshore marine environment, while the basin coastline was located far to the west. [ABSTRACT FROM AUTHOR]

This study documents Middle to Late Ordovician conodont faunas primarily from the Billabong Creek Formation exposed in the Gunningbland area located west of Parkes and northwest of Forbes in central New South Wales. Forty-four identifiable conodont species recovered from 105 limestone samples in this area form the basis of the most complete biostratigraphic succession in shallow-water facies known through this interval from Australia. Four conodont biozones are recognised, extending from the middle Darriwilian Histiodella holodentata–Eoplacognathus pseudoplanus and Eoplacognathus suecicus biozones, through the upper Darriwilian Pygodus serra Biozone, to the Pygodus anserinus Biozone spanning the uppermost Darriwilian to basal Sandbian interval. A lower to middle Sandbian carbonate gap coincides with an unzoned interval, followed by the successively younger Belodina compressa, Phragmodus undatus and Taoqupognathus blandus conodont biozones in the upper Sandbian to lower Katian. The T. blandus Biozone directly correlates with the detailed conodont biozonation established in Katian limestones of the Molong Volcanic Belt further east. These age determinations provide much improved precision for correlation within Phases 2 and 3 in the mineral-rich Macquarie Volcanic Province. Analysis of conodont biofacies data supports an enhanced understanding of the geological evolution of the Macquarie Volcanic Province by interpreting the interplay between volcanic activity and carbonate deposition. Conodont studies in the Billabong Creek Formation of the Gunningbland area reveal the only known biostratigraphic succession in Australia that extends continuously from the middle Darriwilian to basal Sandbian. Three Late Ordovician (late Sandbian to early Katian) conodont biozones in the upper Billabong Creek Formation correlate precisely with carbonates of the Molong Volcanic Belt to the east. Revised stratigraphic definitions of the Billabong Creek and Gunningbland formations are provided. [ABSTRACT FROM AUTHOR]

The present paper describes the lower Upper Devonian conodont fauna from the upper units of Muth Formation, Spiti Valley, Himalaya.

Previously unidentified small (up to 1.3 mm in length), gently curved hollow spines composed of calcium phosphate and derived from the upper Famennian (Devonian) of the Holy Cross Mountains in central Poland are described. They are similar to the type species of Phakelodus, but show some distinct morphological differences, therefore, have been included into Phakeloides polonicus gen. et sp. nov. The studied specimens of that species show relatively massive mineral structure characterized by significant porosity with well-preserved major structural features. The outer layer of the spines is, in contrary, fragmentarily preserved, and exposes distinct mosaic-like ornamentation of the surface of the middle layer, which consists of obliquely arranged, shallow furrows. Geochemical analyses of the Devonian Phakeloides polonicus gen. et sp. nov. spines have revealed the presence of a weaker mineralized structure, compared to conodont apatite, composed of a diagenetic phosphate phase. It is characterized by moderate cathodoluminescence intensity, elevated concentrations of iron and sulphur as well as decreased concentrations of strontium, calcium, and phosphorus. The "Orsten" type, early diagenetic phosphatization of the outer layer of the spines is not observed in studied specimens of Phakeloides polonicus gen. et sp. nov., contrary to the previously investigated Furongian (Cambrian) material. This points to the low rate of diagenetic phosphatization, which was likely enabled by very slow sedimentation and long residence time of the spines close to sediment-water interface at varying redox conditions and significant flux of phosphate ions. [ABSTRACT FROM AUTHOR]

Significant advance in the understanding of the Late Triassic evolution of conodonts and their final disappearance has been made recently. However, the relevant information is rather fragmented and inconsistent. Its critical assessment is undertaken in order to synthesise the new lines of evidence. The final disappearance of conodonts, which should be distinguished from their regional disappearances and precedent diversity changes, occurred at the Rhaetian–Hettangian transition. It was not preceded by a gradual decline: conodonts were able to diversify in the Late Triassic and to survive several biotic crises/turnovers. Their diversity dynamics corresponded (at least, partly) to the eustatic fluctuations similarly to how this occurred during the entire history of this fossil group. [ABSTRACT FROM AUTHOR]

A conodont fauna of late Tremadocian to early Floian age (Early Ordovician) is documented from the Yinchufu Formation of Zhejiang Province, South China. It is characterized by the occurrence of two species of Prioniodontidae, a new species of Prioniodus and Acodus triangularis. Prioniodus antiquus sp. nov. may represent the most primitive species of Prioniodus , which is one of the earliest conodont genera with a ramiform—pectiniform apparatus. Based on the review of nearly 200 species originally assigned to Prioniodus , six multielement species are confirmed to belong to this genus. Morphological changes of these six species shows that they form an evolutionary lineage directly evolved from an adentate species, likely Acodus triangularis which has been reported from South China, Australia and from the Precordillera of western Argentina. Origination of the ramiform—pectiniform apparatuses as represented by the appearances of Prioniodus through late Tremadocian to Floian of the Early Ordovician might be a major response of the 'conodont animals' to occupy and adapt to the increasingly diversified environments in the shelf and slope settings. The biofacies distribution of the six Prioniodus species indicates that Prioniodus might have originated in deep-water slope settings and progressively spread into distal and then interior shelves in the late Tremadocian and diversified in the Floian, with Prioniodus amadeus possibly representing a relict species that survived into the Middle Ordovician and was restricted to shallow water environments. • A case study investigates the origination of the ramiform—pectiniform apparatus. • The grouping of the six Prioniodus species and their evolutionary relationships are discussed. • Prioniodus probably originated in deep-water environments and progressively spread into distal and then interior shelves. [ABSTRACT FROM AUTHOR]