The earliest turrilepadid: a machaeridian from the Lower Ordovician of the Northwest Highlands (original) (raw)
Related papers
Late Paleozoic turrilepadid machaeridians from North America
Acta Palaeontologica …, 1996
Turrilepadids are not uncommon in late Paleozoic shales being often associated wit1l ostracodes, foraminifers, and minute molluscs. In North America they range from the late Missippian (Chesterian) to early Permian (Leonardian). Sclerites of the inner scleritome row are more common than outer sclerites. Some clusters have been found. Sclerite consists of two layers with the thicker, lower layer penetrated by a transverse tubular structures oriented perpendicular to the sclerite surface, which may represent canals related to ttre papillae on the inner surface of ttre sclerite. Turrilepas Lepros sp. n., T. trigonindes sp. n., T, asketos sp. n., Clnrkeolepis alloeospinosa sp. n., and Ambonlepidas petalas gen. et sp. n. are proposed.
A subaqueous welded tuff from the Ordovician of County Waterford, Ireland
Journal of Volcanology and Geothermal Research, 1996
The Metal Man Tuff (MMT) from the Ordovician of County Waterford, Ireland was emplaced and welded in water depths greater than the thickness of the pyroclastic flow. The MMT is the basal member of the Middle Tramore Volcanic Formation (MTVF) of the 5-km-thick Tramore Group. The MMT consists of a IO-m-thick basal graded zone that represents a pyroclastic flow consisting of angular clasts of black mudstone, pumice, gray flow banded rhyolite, and pink massive rhyolite set in a matrix of non-deformed ash shards and pumice. Maximum grain size grades from large cobbles and small boulders to pebbles. The basal lo-30 cm is depleted with respect to the largest boulders resulting in an inversely graded basal layer. The basal graded zone passes upward into a transition zone with a strong eutaxitic foliation defined by elongated fiamme of mudstone and flattened pumice. Overlying this is an upper welded zone with a pronounced eutaxitic foliation, columnar jointing, flattened ash shards and shards deformed around phenocrysts and spheroids.
Scottish Journal of Geology, 2017
Additional machaeridian specimens from the Wether Law Linn Formation (Telychian) have increased our knowledge of this poorly recorded but abundant group in the Pentland Hills, located a few kilometres SE of Edinburgh. A new type of anterior outer shell plate is described and is compared with material previously described from the same horizon and locality. Moreover, a new species of Plumulites is established on the basis of a disarticulated but close association of shell plates.
Revision and definition of the C. wilsoni graptolite Zone (middle Ordovician) of southern Scotland
Transactions of the Royal Society of Edinburgh: Earth Sciences, 1994
Critical collecting, measurement of sections and taxonomic reassessment through the Climacograptus wilsoni Zone (basal Lower Hartfell Formation) of the southern Scottish graptolite zonal sequence suggests that, although only locally developed, it is an easily recognisable and useful biostratigraphic interval. The North Cliff of Hartfell Spa is defined as type section for both the base of the Lower Hartfell Formation and that of the C. wilsoni Zone. The zonal assemblage is figured and described, with particular emphasis being placed on the distinctive species C. wilsoni which has not been redescribed since the beginning of this century.
A revised graptolite biostratigraphy for the lower Caradoc (Upper Ordovician) of southern Scotland
Scottish Journal of Geology, 2004
Biostratigraphical evaluation of graptolites from more than 160 localities in the lower Caradoc of southern Scotland does not differentiate a discrete assemblage diagnostic of the Climacograptus bicornis peltifer Biozone. The lowermost Caradoc Nemagraptus gracilis Biozone is redefined by the partial-range of N. gracilis below the appearance of Climacograptus bicornis s.l. The succeeding C. bicornis Biozone is divisible into (1) a lower Subzone of Orthograptus apiculatus and Dicranograptus ziczac, identified also by the appearance of Amplexograptus leptotheca, Dicranograptus tardiusculus and several other taxa, and (2) an upper Subzone of Climacograptus wilsoni, marked by the first appearance of C. wilsoni. Nemagraptus gracilis and Didymograptus (s.l.) superstes range into the lower part of the apiculatus-ziczac Subzone, above which is a poorly characterized interval that is approximately equivalent of the 'peltifer' Biozone of former usage. The bicornis Biozone is the approximate equivalent to the C. bicornis Biozone of North America, and, at least in part, of the foliaceus (or multidens) Biozone of southern Britain. It is succeeded in Scotland by the clingani Biozone.
Ordovician faunas in mass-flow deposits, Southern Scotland
Terra Nova, 1992
In the Ordovician Northern Belt of the Southern Uplands, basal volcanics (Arenig) are followed by cherts (Llanvim-?Llandeilo), then by graptolite shales (LlandelbLower Caradoc), and finally by Caradoc greywackes. Within the greywackes (Kukcolm Formation) are a number of occurrences of fossiliferous conglomerate and overlying mudstone; these can be traced along-strike for some 30 km. The conglomerates, and especially the mudstones, yield rich mid-Caradoc shelly assemblages; brachiopods (20 spp.), trilobites (14 spp.), gastropods, bivalves, bryozoans, and the first known Palaeozoic scleractiniamorph coral. These occurrences are interpreted as mass-flow deposits derived by downslope movement from a now-vanished shelf to the North, and may belong either to a single gigantic debris flow event, or to a series of smaller, but roughly contemporaneous flows. Strong faunal similarities to faunas at Girvan (western Scotland), and Tyrone (Northern Ireland), lying North of the Southern Upland Fault may suggest sinistral strike-slip movement of no more than a few hundred kilometres.
Journal of The Geological Society, 1998
A chain of pellets (Neonereites uniserialis), usually attributed to a coelomate or pseudocoelomate metazoan, is described from the middle Dalradian Bonahaven Formation of western Scotland, in sandstones not far above the Port Askaig Tillite. This trail lies more than 8 km below U-Pb zircon-dated Tayvallich lavas (595 4 Ma) and predates early deformation plus intrusion by granites at Ben Vuirich dated at 597 11 and 590 2 Ma. U-Pb zircon chronology for early metazoan evolution suggests that this is the earliest putative evidence for coelomates or pseudocoelomate discovered so far, with a minimum 'interglacial' age of c. 600 Ma . It is from about this time that a fall takes place in the maximum 13 C of carbonates, suggestive of a decline in the long term rate of carbon burial. One explanation for this decline is the increasing impact of metazoan bioturbation through the late Neoproterozoic to Cambrian interval.
Geological Journal, 2015
The Late Ordovician ostracod fauna recorded from the Girvan district, southwest Scotland, comprises 54 species from 26 genera and 15 families, but includes 22 species described in open nomenclature and a further 17 that are considered as nomina dubia. The ostracods include representatives of the podocope suborders Palaeocopina, Binodicopina, Leiocopina and Metacopina, and the new genera and species Danemestrinus scotus n. gen. et sp., Leperditella girvanensis n. sp. and Krausella jonesiana n. sp. are described. The fauna includes several species that allow inter-continental correlation with the Late Ordovician succession of North America, including the Sandbian species Eurychilina sunbloodensis, Balticella deckeri, Baltonotella parsispinosa and Hippula ventrospinosa. The Katian species Kinnekullea comma has correlative value between Scotland, Ireland, England and the East Baltic. Biogeographically, the Girvan ostracod fauna of Sandbian age shows strong affinities at species-level with the fauna of palaeocontinental Laurentia, but from the early Katian onwards there are species level links with the Baltic region, and some common taxa at generic and species-level with palaeocontinental Avalonia. Les ostracodes fini-ordoviciens du district de Girvan, sud-ouest de l'Écosse RÉSUMÉ La faune d'ostracodes podocopes de la fin de l'Ordovicien du district de Girvan au sud-ouest de l'Écosse comprend 54 espèces réparties en 26 genres et 15 familles, dont 22 espèces sont décrites en nomenclature ouverte, et 17 sont nomina dubia. Les ostracodes comprennent des représentants des sous-ordres de podocopes, Palaeocopina, Binodicopina, Leiocopina et Metacopina, ainsi que les nouveaux genres et espèces Danemestrinus scotus n. gen. et sp., Leperditella girvanensis n. sp. et Krausella jonesiana n. sp. qui sont décrits ici. La faune contient plusieurs espèces qui permettent une corrélation intercontinentale avec la succession fini-ordovicienne d'Amérique du Nord, comprenant les espèces sandbiennes Eurychilina sunbloodensis, Balticella deckeri, Baltonotella parsispinosa et Hippula ventrospinosa. L'espèce du Katien Kinnekullea comma a une valeur corrélative entre l'Écosse, l'Irlande, l'Angleterre et l'est de la région balte. Du point de vue biogéographique, la faune sandbienne d'ostracodes de Girvan présente des affinités au niveau spécifique avec la faune paléocontinentale laurentienne, mais à partir du début du Katien, il existe des liens au niveau spécifique avec la région balte, et des taxons communs au niveau générique et spécifique avec la faune paléocontinentale avalonienne. [Yves Candela]. Spätordovizische Ostrakoden aus der Region Girvan, Südwest-Schottland ZUSAMMENFASSUNG Die spät-ordovizische Ostrakodenfauna (Podocopida) aus der Region Girvan im Südwesten von Schottland umfasst 54 Arten, 26 Gattungen und 15 Familien. 22 Arten werden in offener Nomenklatur und 17 Arten als nomina dubia beschrieben. Die Ostrakoden der Ordnung Podocopida beinhalten Vertreter der Unterordnung Palaeocopina, Binodicopina, Leiocopina und Metacopina. Die neuen Gattungen und Arten Danemestrinus scotus n. gen. et sp., Leperditella girvanensis n. sp. und Krausella jonesiana n. sp. werden beschrieben. Die Fauna umfasst mehrere Arten aus dem frühen Oberordovizium (Sandbium), wie Eurychilina sunbloodensis, Balticella deckeri, Baltonotella parsispinosa und Hippula ventrospinosa, die eine biostratigraphische Korrelation zwischen der spät-ordovizischen Sukzession in Schottland und Nordamerika erlauben. Kinnekullea comma, eine Art aus dem Katium, erlaubt eine biostratigraphische Korrelation zwischen Schottland, Irland, England und dem Ostbaltikum. Biogeographisch zeigt die girvanische Ostrakodenfauna aus dem Sandbium auf Artniveau starke Ähnlichkeit mit der Fauna des Paläo-Kontinents Laurentia. Seit dem frühen Katium kônnen jedoch auf Artniveau Verbindungen mit dem Baltikum festgestellt werden. Mit Beginn des Katiums existieren gemeinsame Arten und Gattungen ausserdem auf dem Paläo-Kontinent Avalonia. [Ulrich Salzmann]. Позднеордовикские остракоды из района Герван в юго-западной Шотландии PЕЗЮМЕ Фауна позднеордовикских остракод-подокопид из района Герван в юго-западной Шотландии включает представителей 54 видов, относяшихся к 26 родам и 15 семействам. 22 вида из этого числа описаны в открытой номенклатуре, а еще 17 видов рассматриваются как nomina dubia. Изученные остракодыподокопиды относятся к подотрядам Palaeocopina, Binodicopina, Leiocopina и Metacopina. В их числе три новых вида и один новый род: Danemestrinus scotus n. gen. et sp., Leperditella girvanensis n. sp. и Krausella jonesiana n. sp. Фауна остракод включает несколько видов, которые позволяют провести межконтинентальную корреляцию с позднеордовикской последовательностью Северной Америки. Это такие таксоны, как Eurychilina sunbloodensis, Balticella deckeri, Baltonotella parsispinosa и Hippula ventrospinosa, характерные для сандбийского века. Катийский вид Kinnekullea comma имеет значение при корреляциях разрезов Шотландии с Ирландией, Англией и Восточной Прибалтикой. В отношении биогеографии остракодовая фауна района Гервана в течении сандбийского века обнаруживает значительное сходство на видовом уровне с фауной палеоконтинента Лаврентия. Однако, с начала катийского века в ее составе появляются виды, общие с Балтийским регионом, а кроме того, некоторые виды и роды, известные также и на Авалонском палеоконтиненте. [Leonid Popov].
Precambrian Research, 1997
The major and trace element geochemistry of matrix materials from glaciogenic diamictites (unsorted polymictic conglomerates consisting of clasts scattered throughout a finer grained matrix) of the Neoproterozoic Port Askaig Tillite of western Scotland shows evidence of an upward change in provenance. Values for a carbonate-corrected Chemical Index of Alteration (CIA) are fairly high (~ 70-80) in the lower diamictites, suggesting that they were derived mainly from an older sedimentary cover (older Dalradian Formations) that had undergone a previous weathering cycle. Low CIA values, more typical of unweathered material, were obtained from diamictites in the upper part of the formation. Thus, deposition of the Port Askaig diamictites is thought to involve a change in provenance, with unroofing of a cover of older sedimentary rocks and exposure of basement rocks. In spite of these inferred differences in provenance, diamictite materials throughout the formation have very uniform chondrite-normalized rare earth element (REE) distributions. REE distribution patterns from the diamictites closely resemble that of average post-Archean shales (PAAS), with a significant negative Eu anomaly and typical enrichment in LREE. These results, together with the presence of uniform (La/Yb)N ratios throughout the formation, suggest that the sedimentary cover rocks from which the lower diamictites were derived, were themselves derived from a similar post-Archean basement. A Th/Sc versus Sc plot suggests that siliciclastic matrix material in the lowest diamictite was derived essentially from provenances similar to PAAS. The higher diamictites appear to have been derived from a mixture of granitic material and PAAS, in a ratio of up to ca 4: 1. Sparse sedimentary structures suggest derivation of the Port Askaig Tillite from the southeast but the exact source remains unknown.