Proc. Estonian Acad. Sci. Geol., 1998, 47, 2, 51-76 DISTRIBUTION OF SILURIAN AND LOWER DEVONIAN VERTEBRATE MICROREMAINS AND CONODONTS IN THE BAILLIE-HAMILTON AND CORNWALLIS ISLAND SECTIONS, CANADIAN ARCTIC Tiiu MARSSa, Michael ...
The Old Red Sandstone Continent was one of the major landmasses of the Devonian period, as a result of Early Palaeozoic orogenies. Numerous vertebrate-bearing fossiliferous localities are known from this palaeocontinent. They come from... more
The Old Red Sandstone Continent was one of the major landmasses of the Devonian period, as a result of Early Palaeozoic orogenies. Numerous vertebrate-bearing fossiliferous localities are known from this palaeocontinent. They come from lithofacies varying from, e.g., siliciclastic to carbonate. In Lower Devonian rocks, most macrovertebrate remains have been collected in Old Red Sandstone type sediments, but recent investigations have yielded microvertebrate assemblages in various carbonate sediments. One of the main problems dealing with these Early Devonian vertebrate assemblages is concerned with biostratigraphical correlations between the different facies, and with the standard biostratigraphical zonations (conodonts and miospores in particular). This paper contains a review of vertebrate assemblages of the Lower Devonian Global Stratotype Sections and Points. These GSSP contain a poor record of vertebrates, but most recent samplings are promising as concerned with microremains (...
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Dupret, V., S. Sanchez, D. Goujet, P. Tafforeau, and P. Ahlberg. 2011: Structures crâniennes du plus ancien vertébré à mâchoires (-410 millions d’années) révélé par tomographie synchrotron. 15ème Réunion des Chercheurs Francais en Suède,... more
Dupret, V., S. Sanchez, D. Goujet, P. Tafforeau, and P. Ahlberg. 2011: Structures crâniennes du plus ancien vertébré à mâchoires (-410 millions d’années) révélé par tomographie synchrotron. 15ème Réunion des Chercheurs Francais en Suède, Tekniska Museet, Stockholm, 2011.
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BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to... more
BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.
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From a set of new characters, the phylogeny of placoderms taken as a whole has been investigated using the computer programs PAUP and Mac Clade. The result corroborate the hypothesis of an inclusion of the Phylolepida within the... more
From a set of new characters, the phylogeny of placoderms taken as a whole has been investigated using the computer programs PAUP and Mac Clade. The result corroborate the hypothesis of an inclusion of the Phylolepida within the Arthrodira and the basal position of the Acanthothoraci among Placodermata.
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The Lower and Middle Devonian of northwestern Spitsbergen (Savalbard, Norvegian Arctics) is one of the best examples of vertebrate implication in stratigraphy and palaeobasin analysis. Previous studies of the Red Bay Group (Lochkovian,... more
The Lower and Middle Devonian of northwestern Spitsbergen (Savalbard, Norvegian Arctics) is one of the best examples of vertebrate implication in stratigraphy and palaeobasin analysis. Previous studies of the Red Bay Group (Lochkovian, Lower Devonian) made a notable analysis of the earliest Devonian vertebrate record, and their use in biostratigraphy (e.g. Karataj¯ ut˙ e-Talimaa, 1978; Blieck et al., 1987; Blom and Goujet, 2002). Our current study concerns the Lower to Middle Devonian of the Andrée Land Group, which comprises Wood Bay Formation, aging Pragian to Emsian, and Grey Hoek Formation, representing the Eifelian, as the stratigraphy in this region is yet largely based on the distribution of lithofacies. We have defined two new thelodont assemblages, which represent different depostional phases of the late Lower -early Middle Devonian of the Andrée Land Group. The first, older assemblage comprises turiinid, talivaliid, and furcacaudid thelodonts, and identifies the lower Wood...
We have studied vertebrate microremains from the Lower to Middle Devonian of the Andrée Land Group, comprising the Wood Bay and Grey Hoek formations. We have defined two new thelodont assemblages, which represent different depositional... more
We have studied vertebrate microremains from the Lower to Middle Devonian of the Andrée Land Group, comprising the Wood Bay and Grey Hoek formations. We have defined two new thelodont assemblages, which represent different depositional phases during the late Early to early Middle Devonian formation of the Andrée Land Group. The definition of these two new thelodont assemblages allows us to precisely establish the relative ages of the Lower–Middle Devonian strata. Rare earth element (REE) abundances were measured in a number of thelodont and chondrichthyan microfossil dental tissue biominerals, using laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS). The evaluation of fossil preservation level was performed using semiquantitative spot-geochemistry analyses on finely polished thelodont scale thin-sections using Energy Dispersive X-ray Spectroscopy (EDS), and Electron Backscattering Diffractometry (EBSD) was applied to detect recrystallization. Stable oxygen isoto...
We have studied vertebrate microremains from the Lower to Middle Devonian of the Andrée Land Group, comprising the Wood Bay and Grey Hoek formations. We have defined two new thelodont assemblages, which represent different depositional... more
We have studied vertebrate microremains from the Lower to Middle Devonian of the Andrée Land Group, comprising the Wood Bay and Grey Hoek formations. We have defined two new thelodont assemblages, which represent different depositional phases during the late Early to early Middle Devonian formation of the Andrée Land Group. The definition of these two new thelodont assemblages allows us to precisely establish the relative ages of the Lower–Middle Devonian strata. Rare earth element (REE) abundances were measured in a number of thelodont and chondrichthyan microfossil dental tissue biominerals, using laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS). The evaluation of fossil preservation level was performed using semiquantitative spot-geochemistry analyses on finely polished thelodont scale thin-sections using Energy Dispersive X-ray Spectroscopy (EDS), and Electron Backscattering Diffractometry (EBSD) was applied to detect recrystallization. Stable oxygen isoto...
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ABSTRACT Taylor & Francis makes every effort to ensure the accuracy of all the information (the "Content") contained in the publications on our platform. However, Taylor & Francis, our agents, and our... more
ABSTRACT Taylor & Francis makes every effort to ensure the accuracy of all the information (the "Content") contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content.
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ABSTRACT Studies of fossils collected from the Nictaux–Torbrook and Bear River synclines (Nova Scotia) allow a reexamination of the Siluro-Devonian stratigraphy of the Meguma terrane. The location of this terrane relative to the main... more
ABSTRACT Studies of fossils collected from the Nictaux–Torbrook and Bear River synclines (Nova Scotia) allow a reexamination of the Siluro-Devonian stratigraphy of the Meguma terrane. The location of this terrane relative to the main paleocontinents of the circumatlantic domain during this period is discussed. Wenlockian, Ludlovian, and Pridolian biostratigraphic horizons have been dated. The benthic fauna of the Torbrook Formation are assigned here to the Lochkovian, Pragian, and Lower Emsian. The Pridolian fauna shows northern European affinities. Thus, the Meguma terrane probably belonged to the North Atlantic domain, as for the Avalon terrane, and occupied a southern position in the "Euramerica" plate during this period. The Devonian fauna belongs to the "old world realm" and shows north Gondwanian and Rhenish affinities. As early as the Lochkovian, species known from both the Rhenish and north Gondwanian domains are recognized in Meguma, as well as others reported so far only from northwestern Africa, Iberian Peninsula, and (or) Armorican Massif. The presence of Rhenish fauna confirms the postulated location for the Meguma terrane during the Upper Silurian since this fauna is representative of southern Baltica marginal areas in Europe. On the other hand, the presence of north Gondwanian fauna implies close relationships with western European margin of Gondwana. The lack of a wide oceanic gap separating north Gondwana and Euramerica can explain the faunal exchanges during Lower Devonian times between western Europe and easternmost Appalachian province despite the presence of a physical barrier.
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Non-professional taxonomists have been responsible for describing more than half of the animal species discovered in Europe from 1998 to 2007 (see also Nature 467, 788; 2010). The extraordinary current rate of description of new species... more
Non-professional taxonomists have been responsible for describing more than half of the animal species discovered in Europe from 1998 to 2007 (see also Nature 467, 788; 2010). The extraordinary current rate of description of new species makes Europe an unexpected ...
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ABSTRACT Extant vertebrates form two clades, the jawless Cyclostomata (lampreys and hagfishes) and the jawed Gnathostomata (all other vertebrates), with contrasting facial architectures. These arise during development from just a few key... more
ABSTRACT Extant vertebrates form two clades, the jawless Cyclostomata (lampreys and hagfishes) and the jawed Gnathostomata (all other vertebrates), with contrasting facial architectures. These arise during development from just a few key differences in the growth patterns of the cranial primordia: notably, the nasal sacs and hypophysis originate from a single placode in cyclostomes but from separate placodes in gnathostomes, and infraoptic ectomesenchyme migrates forward either side of the single placode in cyclostomes but between the placodes in gnathostomes. Fossil stem gnathostomes preserve cranial anatomies rich in landmarks that provide proxies for developmental processes and allow the transition from jawless to jawed vertebrates to be broken down into evolutionary steps. Here we use propagation phase contrast synchrotron microtomography to image the cranial anatomy of the primitive placoderm (jawed stem gnathostome) Romundina, and show that it combines jawed vertebrate architecture with cranial and cerebral proportions resembling those of cyclostomes and the galeaspid (jawless stem gnathostome) Shuyu. This combination seems to be primitive for jawed vertebrates, and suggests a decoupling between ectomesenchymal growth trajectory, ectomesenchymal proliferation, and cerebral shape change during the origin of gnathostomes.
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In the Arctic, Spitsbergen (Svalbard archipelago) comprises a Caledonian metamorphic basement structured around 420 Ma, cut by faults that demarcate a sedimentary, NS graben, filled up by siliclastic detrital series of Old Red Sandstone... more
In the Arctic, Spitsbergen (Svalbard archipelago) comprises a Caledonian metamorphic basement structured around 420 Ma, cut by faults that demarcate a sedimentary, NS graben, filled up by siliclastic detrital series of Old Red Sandstone facies (ca. 418-ca. 326 Ma), with a lateral cumulative thickness of 6300 to more than 10,800 meters. The latter yields a particularly abundant fauna of early fishes, which are the main guide fossils for stratigraphic purposes (Agnatha, Placodermi and Crossopterygii). These sediments are faulted and ...
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Les placodermes acanthothoracides sont parmi les vertébrés gnathostomes les plus basaux phylogénetiquement et morphologiquement. Néanmoins, une bonne connaissance anatomie crânienne fait défaut, et à ce jour un seul genre... more
Les placodermes acanthothoracides sont parmi les vertébrés gnathostomes les plus basaux phylogénetiquement et morphologiquement. Néanmoins, une bonne connaissance anatomie crânienne fait défaut, et à ce jour un seul genre (Brindabellaspis) a été décrit en détails. Nous présentons le modèle en 3 dimensions d'un crâne presque complet de Romundina stellina, un petit acanthothoracide du Dévonien inférieur de l'Archipel Arctique Canadien, décrit originellement par Ørvig (1975). Le spécimen a été microtomographié ...