12 research outputs found

    Microstructure of Common Reef-Building Coral Genera Acropora, Pocillopora, Goniastrea and Porites : Constraints on Spatial Resolution in Geochemical Sampling

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    Scleractinian corals are increasingly used as recorders of modern and paleoclimates. The microstructure of four common reef-building coral genera is documented here: Acropora, Pocillopora, Goniastrea, and Porites. This study highlights the complexity and spatial variability of skeletal growth in different coral genera and suggests that a single growth model is too generalized to allow the accurate depiction of the variability observed in the four genera studied. New models must be introduced in order for coral skeletogenesis to be understood adequately to allow coral skeletons to serve as repositories of temporally constrained geochemical data. Owing to differences in microstructural patterns in different genera, direct observation of microstructural elements and growth lines may be necessary to allow microsamples to be placed into series that represent temporal sequences with known degrees of time averaging. Such data are critical for constraining microsampling strategies aimed at developing true time series geochemical data at very fine spatial and temporal scales

    Earliest Mississippian rugose corals of eastern Australia: post-disaster fauna across the Devonian-Carboniferous boundary?

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    The most earliest Mississippian rugose corals are post-disaster taxa occurring in a biosphere strongly modified by the crises associated with the Devonian-Carboniferous Boundary. In Western Europe, basal Tournaisian rugose corals belong to the genera Conilophyllum, Hebukophyllum and Kizilia. Conilophyllum and Hebukophyllum are either homeomorphs or close relatives of each other and are likely post-disaster fauna showing wide morphological plasticity but with an unknown origin. Kizilia is a Lazzarus taxon, known also from basal Tournaisian strata of China, that suddenly reappeared at the Devonian-Carboniferous Boundary being related to the mid-Devonian stringophyllids. The deeper basinal facies of Western Europe (Montagne Noire, Rhenish Mts, Thuringia, Upper Franconia) yield mostly small non-dissepimented solitary rugose corals, together with some dissempimented ones, amongst which are mostly long-ranging taxa. In N America, Vesiculophyllum, a genus very similar, and probably related, to Kizilia occurs together with non-dissepimented long-ranging corals. Like most of the basal Tournaisian dissepimented rugose corals, Cystodactylon orbum gen. et sp. nov. and Gudmania darumbalae gen. et sp. nov. from the basal Tournaisian of eastern Australia are interpreted as post-disaster fauna. Their origin is not understood to date and they seemingly left no descent in the Carboniferous. Their stratigraphic range is extremely limited as they so far are known only in small reefs at the base of the lower Tournaisian Gudman Formation in the type area

    Cionodendron and related lithostrotionid genera from the Mississippian of eastern Australia: systematics, stratigraphy and evolution

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    Denayer, J. & Webb, G.E., 26.2.2015. Cionodendron and related lithostrotionid genera from the Mississippian of eastern Australia: systematics, stratigraphy and evolution. Alcheringa 39, xxx–xxx. ISSN 0311-5518. The Mississippian colonial rugose corals of eastern Australia are taxonomically reviewed and assigned to formal genera. Their homeomorphy with the Eurasian genera Siphonodendron and Lithostrotion but also Heterostrotion resulted from parallel evolution within the Lithostrotionidae. Fasciculate species are reassigned to Cionodendron, as they share a robust columella, septotheca and two series of tabellae. Based on common characters, three species groups are recognized: the C. columen Group (characterized by the occurrence of parricidal and non-parricidal increase), the C. hallense Group (development of second-order lonsdaleoid dissepiments) and the C. arundineum Group (lacking the previous characters). Fourteen species are recognized, one being new (C. smithi sp. nov.) and two documented for the first time in the area. The oldest species are late Tournaisian in age, but the genus is most diverse in the middle–late Visean. Several morphological lineages are recognized within the three groups. The massive species are classified in the newly erected genus Australastraea that likely evolved from one of the early species of Cionodendron in the early Visean. Eleven species were identified, two being newly described (A. arcifera, sp. nov., A. carinata sp. nov.) and two others documented for the first time. Australastraea is characterized by a septotheca that is commonly discontinuous, conferring a pseudo-cerioid or astreoid habit. Two morphological groups are identified: the A. wilkinsoni Group (small corallites with simple narrow dissepimentarium) and the A. columnare Group (large corallites with complex dissepimentarium). The small fasciculate species previously referred to Lithostrotion williamsi are here reassigned to the new genus Pickettodendron, which differs from Cionodendron by the lack of minor septa and presence of a complete tabularium but is, nevertheless, relatively closely related to that genus. Pickettodendron is represented by three species, one being new (P. nudum sp. nov.), and is restricted to the early (–‘middle’) Tournaisian. A polyphyletic origin of the Cionodendroninae is considered, with Cionodendron and Australastraea originated in a first species of Amygdalophyllum and Pickettodendron originated in a second one. The biostratigraphic value of the Cionodendroninae is currently limited owing to the poor stratigraphic coverage of appropriate facies but correlations were made possible by the identification of A. columellaris and C. consanguineum in the early Visean of New South Wales and Queensland, and A. columnare and A. sp. in the middle–late Visean of both states. The Cionodendroninae assemblages of eastern Australia are strongly endemic and possibly represent one of the scarce remains of the Panthalassa Province. Julien Denayer [[email protected]], Evolution and Diversity Dynamics Lab, Geology Department, University of Liège, B18, Allée du Six-Août, Sart Tilman, B-4000 Liège, Belgium; Gregory E. Webb [[email protected]], Integrated Palaeoenvironmental Research Group, School of Earth Sciences, University of Queensland, QLD 4072, St-Lucia, Australia

    Taxonomy, Biostratigraphy and Palaeobiogeography of the Late Tournaisian rugose corals of north-western Turkey

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    This article provides the first taxonomic description of Ivorian (Late Tournaisian, Early Carboniferous) rugose coral associations from north-western Turkey (Zonguldak and Bartın). Eleven species belonging to ten genera are described, one species is new. Three biostratigraphic assemblages are recognized. The oldest assemblage includes Cyathaxonia cornu, Cyathoclisia uralensis, ‘Lophophyllum’ konincki and Uralinia multiplex. This corresponds to the RC3 Biozone (early Ivorian). The middle assemblage in characterised by Amplexus coralloides, Sychnoelasma hawbankense and Zaphriphyllum daleki sp. nov. and is correlated with the early late Ivorian RC4α Biozone. The youngest assemblage (RC4β1 Biozone, latest Ivorian) is composed of Corphalia fourmarieri, Corphalia sp. and Amydgalophyllum? sp. These three assemblages have a low specific and generic diversity compared to time-equivalent assemblages but contain genera with a wide distribution in the Palaeotethys Ocean, such as Cyathoclisia, Uralinia and—in a lesser extend—Zaphriphyllum, as well as typically European taxa such as Corphalia and Sychnoelasma. These latter two, identified for the first time outside of Europe, allow associating north-western Turkey with the European Coral Province
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