Paired δ13Ccarb and δ13Corg records of Upper Ordovician (Sandbian–Katian) carbonates in North America and China: Implications for paleoceanographic change

2008 ◽  
Vol 270 (1-2) ◽  
pp. 166-178 ◽  
Author(s):  
Seth A. Young ◽  
Matthew R. Saltzman ◽  
Stig M. Bergström ◽  
Stephen A. Leslie ◽  
Chen Xu
Keyword(s):  
North America ◽  
Upper Ordovician ◽  
Paleoceanographic Change

Upper Ordovician ostracods from the Cautley district, northern England: Baltic and Laurentian affinities

2001 ◽  
Vol 138 (5) ◽  
pp. 589-607 ◽  
Author(s):  
MARK WILLIAMS ◽  
PHILIP STONE ◽  
DAVID J. SIVETER ◽  
PAULINE TAYLOR
Keyword(s):  
North America ◽  
Significant Extent ◽  
Baltic Region ◽  
Upper Ordovician ◽  
Northern Germany ◽  
Iapetus Ocean ◽  
Windermere Supergroup ◽  
Distributional Patterns ◽  
Anticosti Island ◽  
The Baltic

The Cautley Mudstone Formation and Cystoid Limestone Member of the Ashgill Formation (Windermere Supergroup; Ashgill Series), from the Cautley district of northern England, has yielded an ostracod fauna of more than 30 species. Many of these have short ranges, permitting recognition of stratigraphically successive Pusgillian–lower Cautleyan, middle–upper Cautleyan, and Rawtheyan ostracod faunas. Several species are also known from the upper Ordovician of North America (Anticosti Island), Scotland (Girvan district) and the Baltic region (Estonia, glacial erratic boulders of northern Germany), providing evidence to correlate upper Ordovician successions in these areas. The ostracods include abundant podocopes, at some horizons accounting for more than 80% of the fauna. Binodicopes are also common, but palaeocopes are rare. Assemblages are typical of a clastic dominated open marine shelf setting. Diversity at most horizons is low (c. 3–5 species), but reaches a peak of between 13–14 species in middle Cautleyan horizons. Lower diversity at Pusgillian and Rawtheyan horizons coincides with the encroachment of deeper marine-shelf facies which were probably hostile to Ordovician benthonic ostracods. Some of the ostracods (particularly Aechmina) have distributions suggesting tolerance of a range of mid- to deep shelf benthonic palaeoenvironments, but none were pelagic. During Ashgill times the Cautley district (part of palaeocontinental Avalonia) was replete with ostracod genera and species which also occur in the Baltic region (palaeocontinental Baltica; more than 90% generic similarity) and to a lesser, but nonetheless significant extent in North America and Scotland (parts of palaeocontinental Laurentia). Such trans-Tornquist Sea and Iapetus Ocean distributional patterns add to previous ostracod data that support models which show palaeogeographical proximity of Avalonia and Baltica, and Avalonia and Laurentia, by Ashgill times. The widely cited observation, that trans-Iapetus ostracod faunas remained strictly provincial until the mid-or late Silurian, cannot be sustained.

Flexible crinoids from the Upper Ordovician Maquoketa Formation of the northern midcontinent and the evolution of early flexible crinoids

2001 ◽  
Vol 75 (2) ◽  
pp. 370-382 ◽  
Author(s):  
James C. Brower
Keyword(s):  
New Species ◽  
North America ◽  
Late Ordovician ◽  
Upper Ordovician ◽  
Middle Ordovician

Three flexible crinoids occur in the Upper Ordovician Maquoketa Formation of Illinois, Iowa, and Minnesota:Protaxocrinus girvanensisRamsbottom, 1961,Clidochirus anebosnew species, andProanisocrinus oswegoensis(Miller and Gurley, 1894).Protaxocrinus girvanensisis also found in the Upper Ordovician of Scotland which indicates that the ocean was narrow enough to allow at least one crinoid species to cross the barrier. The Upper Ordovician of North America and Scotland also share many common crinoid genera. Both phenetic and cladistic methods result in similar phylogenies of flexible crinoids.Protaxocrinuswas derived from a cupulocrinid ancestor during the Middle Ordovician.Clidochirusevolved fromProtaxocrinusor its ancestral stock prior to the Richmondian of the Late Ordovician. The RichmondianProanisocrinusand later anisocrinids are most closely related toClidochirusor its immediate predecessor. Thus, three major lineages of flexible crinoids,Protaxocrinus(taxocrinid group),Clidochirus(icthyocrinid), andProanisocrinus(anisocrinids and homalocrinids), appeared during the Ordovician. Despite their rarity during the Ordovician, all three flexible lineages survived the Latest Ordovician extinction, whereas their more abundant and successful cupulocrinid ancestors were eliminated.

A revised graptolite biostratigraphy for the lower Caradoc (Upper Ordovician) of southern Scotland

2004 ◽  
Vol 40 (2) ◽  
pp. 97-114 ◽  
Author(s):  
Mark Williams ◽  
Adrian W. A. Rushton ◽  
Ben Wood ◽  
James D. Floyd ◽  
Richard Smith ◽  
...  
Keyword(s):  
North America ◽  
Upper Ordovician

SynopsisBiostratigraphical 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.

scholarly journals The only known cyclopygid–‘atheloptic’ trilobite fauna from North America: the upper Ordovician fauna of the Pyle Mountain Argillite and its palaeoenvironmental significance

2012 ◽  
Vol 149 (6) ◽  
pp. 964-988 ◽  
Author(s):  
ALAN W. OWEN ◽  
DAVID L. BRUTON
Keyword(s):  
New Species ◽  
North America ◽  
Deep Water ◽  
Benthic Fauna ◽  
Taxonomic Diversity ◽  
Relative Depth ◽  
Upper Ordovician ◽  
Brachiopod Fauna ◽  
Depth Ranges ◽  
One New Species

AbstractThe trilobite fauna of the upper Ordovician (middle Katian) Pyle Mountain Argillite comprises a mixture of abundant mesopelagic cyclopygids and other pelagic taxa and a benthic fauna dominated by trilobites lacking eyes. Such faunas were widespread in deep water environments around Gondwana and terranes derived from that continent throughout Ordovician time but this is the only known record of such a fauna from North America and thus from Laurentia. It probably reflects a major sea level rise (the ‘Linearis drowning events’) as does the development of coeval cyclopygid-dominated deep water trilobite faunas in terranes that were marginal to Laurentia and are now preserved in Ireland and Scotland. The Pyle Mountain Argillite trilobite fauna occurs with a deep water Foliomena brachiopod fauna and comprises 22 species. Pelagic trilobites (mostly cyclopygids) constitute 36% of the preserved sclerites, and 45% of the fauna is the remains of trilobites lacking eyes, including one new species, Dindymene whittingtoni sp. nov. Three species of cyclopygid are present, belonging in Cyclopyge, Symphysops and Microparia (Heterocyclopyge). Cyclopygids are widely thought to have been stratified in the water column in life and thus their taxonomic diversity reflects the relative depths of the sea-beds on which their remains accumulated. A tabulation of middle and upper Katian cyclopygid-bearing faunas from several palaeoplates and terranes arranged on the basis of increasing numbers of cyclopygid genera allows an assessment of the relative depth ranges of the associated benthic taxa. The Pyle Mountain Argillite fauna lies towards the deeper end of this depth spectrum.

Upper Ordovician graptolites from the top Lower Hartfell Shale Formation (D. clingani and P. linearis zones) near Moffat, southern Scotland

1982 ◽  
Vol 72 (4) ◽  
pp. 229-255 ◽  
Author(s):  
S. Henry Williams
Keyword(s):  
New Species ◽  
North America ◽  
Upper Ordovician ◽  
The North ◽  
Continuous Sequence ◽  
Two New Species ◽  
Shale Formation ◽  
First Time

ABSTRACTThe top 9 m of Lower Hartfell Shale has been collected in 10 cm samples through a continuous sequence on the North Cliff at Dob's Linn. The boundary between the Dicranograptus clingani and Pleurograptus linearis zones is denned for the first time in a measured section, 5.0 m below the top of the Lower Hartfell Shale, with the excavation of the North Cliff proposed as stratotype. The late D. clingani Zone is characterised by Dicranograptus ramosus?, Dicellograptus moffatensis, D. flexuosus [= D. forchhammeri], Climacograptus dorotheus, Glyptograptus daviesi sp. nov., Diplograptus? pilatus sp. nov., Neurograptus margaritatus and Corynoides calicularis. The P. linearis Zone is characterised by Pleurograptus linearis linearis, Amphigraptus divergens divergens, Leptograptus capillaris, Dicellograptus elegans elegans, D. pumilis, D. carruthersi and Climacograptus tubuliferus. A range chart is provided and an attempt is made at a revised correlation of the Scottish succession with coeval zonal sequences in North America and Australia. Twenty-one taxa are described including the two new species noted above.

Upper Ordovician (Sandbian) bryozoan fauna from Argentine Precordillera

2012 ◽  
Vol 86 (5) ◽  
pp. 721-752 ◽  
Author(s):  
Andrej Ernst ◽  
Marcelo Carrera
Keyword(s):  
North America ◽  
San Juan ◽  
Growth Forms ◽  
Upper Ordovician ◽  
Argentine Precordillera

A stenolaemate bryozoan fauna containing 20 species belonging to 18 genera is described from the Las Plantas and Las Aguaditas formations (Upper Ordovician, Sandbian) in San Juan Province, Precordillera of Western Argentina. One genus with one species is new: Argentinodictya lenticulata n. gen. n. sp. (Cryptostomata, Ptilodictyina). Four species are new: one trepostome Parvohallopora parvula n. sp., two cryptostomes Trigonodictya parvula n. sp. and Ptilodictya intermedia n. sp., and phyloporinine Chasmatopora rossae n. sp. The bryozoan assemblage of the Las Plantas Formation is more diverse than that of the Las Aguaditas Formation. Fourteen species are restricted to the Las Plantas Formation, five species occur in both formations, and one species is restricted to the Las Aguaditas Formation. Erect growth forms are dominant in the studied fauna. The majority of bryozoan taxa display palaeobiogeographic relations to Sandbian–Katian deposits of North America, with two species also known from the Katian of Europe.

Designation of a neotype and paraneotype for Conularina triangulata (Raymond, 1905) (Upper Ordovician, eastern North America)

2020 ◽  
Vol 94 (4) ◽  
pp. 796-797
Author(s):  
Heyo Van Iten ◽  
Mario E. Cournoyer ◽  
Michelle Coyne
Keyword(s):  
New York ◽  
North America ◽  
Late Ordovician ◽  
Quebec City ◽  
Eastern North America ◽  
Upper Ordovician ◽  
Thrust Sheet ◽  
City Formation ◽  
Early Late

Conularina triangulata (Raymond, 1905), the genotype of Conularina Sinclair, 1942, is a rare, early Late Ordovician conulariid (Cnidaria, Scyphozoa; Van Iten et al., 2006) having three sides or faces instead of four (Sinclair, 1942, fig. 9; Van Iten, 1992, text-fig. 3E). Originally described from the Valcour Formation (early Sandbian; Dix et al., 2013) on Valcour Island, New York (Sinclair, 1942), C. triangulata has since been found in laterally equivalent strata of the upper Laval Formation (‘Upper Chazy’; Sinclair, 1942) in Laval, Québec, Canada (Sinclair, 1942). From this same unit and area, Sinclair (1942) erected three new, four-sided species of Conularina (C. irrasa, C. raymondi, and C. undosa), and he erected a single four-sided species (C. narrawayi) from the Ottawa Formation (now the Sandbian–Katian Ottawa Group; Dix et al., 2013) at Tétreauville (now Gatineau), Québec. Subsequently, Jerre (1994) reported the occurrence of two species of Conularina in the Upper Ordovician of Sweden. Jerre (1994) also proposed that Eoconularia? forensis Sinclair, 1946 from the Upper Ordovician Citadelle Formation (‘Quebec City’ Formation; Sinclair, 1946) in Québec City, Québec (Promontoire de Québec thrust sheet, Appalachian Humber Zone, Allochtonous Domain; Castonguay et al., 2002) is a species of Conularina.

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