Palaeocope ostracods from the Silurian Wenlock Series of Arctic Canada

2010 ◽  
Vol 47 (6) ◽  
pp. 913-925
Author(s):  
C. Giles Miller ◽  
Mark Williams ◽  
David J. Siveter
Keyword(s):  
Lake Area ◽  
Arctic Canada ◽  
Level Change ◽  
Carbon Isotope Excursion ◽  
Low Diversity ◽  
Cape Phillips Formation ◽  
Global Sea Level ◽  
The Baltic ◽  
Cornwallis Island ◽  
Ostracod Species

Silurian Wenlock Series deposits of the Cape Phillips Formation on Baillie-Hamilton Island and Cornwallis Island, Arctic Canada, have yielded a silicified ostracod assemblage that spans the late Sheinwoodian and Homerian stages. Sixteen palaeocope ostracod species are recorded, including the new species Beyrichia ( Beyrichia ) marssae , Gabrielsella ? copelandi , and Platybolbina ( Abruptobolbina ) adraini . The ostracod faunas can be linked into local trilobite, microvertebrate, and graptolite zonal schemes, and a few of the ostracod species offer potential for local and perhaps wider biostratigraphical correlation. The ostracods are mostly known only from the Cape Phillips Formation, but also include two taxa found in the Wenlock Series of the Avalanche Lake area, Northwest Territories, Canada. Other ostracod species suggest links with Silurian successions in northern Canada and the Baltic. Low-diversity ostracod faunas characterize the level of a marked positive carbon isotope excursion and coeval mid-Homerian regression at the level of the regional Pristiograptus dubius – Gothograptus nassa graptolite Biozone. Comparison with the pattern of distribution of coeval ostracod faunas elsewhere in Canada suggests that diversity changes in the Cape Phillips Formation ostracod faunas are controlled by local palaeoenvironmental factors perhaps linked to global sea-level change.

Complex noncalcified macroalgae from the Silurian of Cornwallis Island, Arctic Canada

2011 ◽  
Vol 85 (1) ◽  
pp. 111-121 ◽  
Author(s):  
Steven T. Loduca ◽  
Michael J. Melchin ◽  
Heroen Verbruggen
Keyword(s):  
New Taxa ◽  
Florida Bay ◽  
Central Axis ◽  
Arctic Canada ◽  
Green Algal ◽  
Cape Phillips Formation ◽  
Macroalgal Assemblage ◽  
Algal Material ◽  
Fifth Order ◽  
Cornwallis Island

Thin beds of silty limestone within a Ludlovian (Ludfordian) section of the Cape Phillips Formation on Cornwallis Island, Arctic Canada, contain numerous specimens of noncalcified macroalgae in association with dendroid and graptoloid graptolites, brachiopods, and trilobites. The algal material, preserved as carbonaceous compressions, represents three new taxa, each characterized by a central axis surrounded by laterals. Laterals ofEocladus xiaoin. gen. n. sp. are thin and branch to the fifth order whereas those ofChaetocladus captitatusn. sp. are undivided and form a distinctive capitulum. Thalli ofPalaeocymopolia nunavutensisn. gen. n. sp. have a branched, serial-segmented form and a corticated structure. On the basis of thallus architecture, all three taxa are assigned to the extant green algal order Dasycladales. Parallels exist between this macroalgal assemblage and a modern macroalgal association in Florida Bay.

The Ordovician–Silurian boundary on Cornwallis and Truro islands, Arctic Canada: preliminary data

1991 ◽  
Vol 28 (11) ◽  
pp. 1854-1862 ◽  
Author(s):  
Michael J. Melchin ◽  
Alexander D. McCracken ◽  
Fred J. Oliff
Keyword(s):  
Sea Level ◽  
Arctic Canada ◽  
Faunal Turnover ◽  
Sea Level Fluctuations ◽  
Continuous Sequence ◽  
Cape Phillips Formation ◽  
Show Evidence ◽  
Conodont Zone ◽  
Continuous Sedimentation ◽  
Cornwallis Island

Four sections of the lower part of the Cape Phillips Formation, two outcrops on northeastern Cornwallis Island and one outcrop and one drill core from Truro Island, Northwest Territories, Canada, provide significant new data on the Ordovician–Silurian boundary. They show evidence of continuous sedimentation through the boundary interval and a continuous sequence of graptolite zones, including the bohemicus and persculptus zones, which have not been previously found in Arctic Canada. Strata yield graptolites, including uncompressed specimens, and conodonts through most of the sections. The ordovicicus conodont Zone occurs within the pacificus to lower persculptus graptolite zones. The nathani conodont Zone contains a "transitional fauna," a mixing of species typical of the preceeding ordovicicus Zone and those generally regarded as Silurian indicators. This conodont zone ranges from the middle of the persculptus graptolite Zone into the lower acuminatus graptolite Zone and, thus, spans the Ordovician–Silurian boundary. The Ordovician–Silurian faunal turnover of the conodonts, therefore, also spans the Ordovician–Silurian boundary and is not coincident with the interval of major graptolite extinction, which occurs earlier, at the end of the pacificus Zone. The base of the kentuckyensis conodont Zone occurs in the acuminatus graptolite Zone. Sedimentologic evidence of the maximum eustatic sea-level drop can be seen within the bohemicus Zone (early Hirnantian) and possibly one or several smaller scale sea-level fluctuations through the underlying zones.

Uncompressed specimens of Monograptus turriculatus (Barrande, 1850) from Cornwallis Island, Arctic Canada

1986 ◽  
Vol 23 (4) ◽  
pp. 579-582 ◽  
Author(s):  
M. J. Melchin ◽  
A. C. Lenz
Keyword(s):  
Canadian Arctic ◽  
Arctic Canada ◽  
Lateral Asymmetry ◽  
Cape Phillips Formation ◽  
Lateral Curvature ◽  
Cornwallis Island

Isolated specimens of Monograptus turriculatus (Barrande, 1850) have been recovered from calcite concretions of the turriculatus Zone (late Llandovery) from the Cape Phillips Formation, Canadian Arctic Islands. The sicula shows ventral as well as dextral lateral curvature, and the thecae show a pronounced lateral asymmetry. This asymmetry is manifest as a tear-shaped aperture, a long, laterally directed spine on the outer apertural margin, and a shorter, ventrally directed spine on the inner apertural margin. The latter spine is totally absent on the proximal thecae.Monograptus sedgwickii (Portlock, 1853) is suggested as a possible ancestor to M. turriculatus.

A Bohemian-type Silurian (Wenlockian) pelecypod faunule from Arctic Canada

1987 ◽  
Vol 61 (3) ◽  
pp. 508-520 ◽  
Author(s):  
John Pojeta ◽  
B. S. Norford
Keyword(s):  
Arctic Canada ◽  
Cape Phillips Formation ◽  
First Time ◽  
Cornwallis Island

The pelecypod genera Slava and Rhombopteria are reported for the first time from Canada, where they occur in a limestone concretion within the Cape Phillips Formation, Cornwallis Island, Arctic Archipelago. These genera are characteristic of Silurian rocks in Bohemia, Czechoslovakia. Graptolites from the same concretion indicate the Monograptus ludensis Zone (uppermost Wenlockian); this age is substantiated by associated conodonts, trilobites, vertebrates, and pelecypods but with less precision. It is difficult to explain the occurrence of Slava and Rhombopteria in the middle of Laurentia on the basis of some map reconstructions of the Wenlockian world.The Canadian material of Slava novaterra n. sp. and Rhombopteria cf. R. mira (Barrande) is described. Leptodesma (Leptodesma) sp. A and an indeterminate grammysiid pelecypod from the same concretion are illustrated. Information is provided to show that Newsomella Foerste, from Wenlockian–Ludlovian rocks of Illinois, Wisconsin, and Tennessee, is not a subgenus of Rhombopteria Jackson.

Early Silurian (Wenlockian) δ13C profiles from the Cape Phillips Formation, Arctic Canada and their relation to biotic events

2005 ◽  
Vol 42 (8) ◽  
pp. 1419-1430 ◽  
Author(s):  
Paula J Noble ◽  
Matthew K Zimmerman ◽  
Chris Holmden ◽  
Alfred C Lenz
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Geochemical Data ◽  
Carbonate Weathering ◽  
Arctic Canada ◽  
Cape Phillips Formation ◽  
Biotic Events ◽  
Extinction Events ◽  
Detrital Carbonate ◽  
Cornwallis Island

Geochemical data from the Cape Phillips Formation, Arctic Canada, are examined in association with three Silurian biotic crises in the graptolite community; the early Wenlockian Ireviken, mid Wenlockian Cyrtograptus lundgreni, and end Wenlockian Colonograptus ludensis extinction events. Positive δ13Corg excursions are associated with the Ireviken and C. lundgreni events, but not the Co. ludensis Event. The Ireviken and C. lundgreni excursions are recognized worldwide and are herein interpreted to be the result of carbonate weathering in response to eustatic sea-level drop. The C. lundgreni excursion is of greater magnitude in the more proximal basin margin section at Abbott River, Cornwallis Island, and is explained by the amplification of a more strongly positive δ13C signature in shallower parts of an epeiric basin during increased exposure and weathering of the carbonate shelf. Excursion C5, within the C. praedeubeli – C. deubeli Zone, is also of regional significance, as it occurs in both the Abbott River section and Twilight Creek section on Bathurst Island, and is also recognized in Estonia, Poland, and England. Excursion C6 is recognized in the Gorstian Stage, yet its regional significance remains equivocal. There is a reasonable general agreement between the shape of the δ13Corg and δ13Ccarb curves, yet the δ13Ccarb curve is largely a record of detrital carbonate derived from the shelf. The δ13Corg curve represents extraction of dissolved inorganic carbon by plankton and thus is more indicative of ambient paleoceanographic conditions. These data are valuable in that they provide a detailed secular marine δ13C curve for the Wenlockian of Arctic Canada from relatively unaltered sections of varying facies whose ages are well constrained by graptolite biostratigraphy.

Insolitignum n.gen. and Palaeoephippium Goodbody 1986 (Radiolaria) from the Lower Silurian of the Cape Phillips Formation, Arctic Canada

1999 ◽  
Vol 36 (12) ◽  
pp. 2051-2057 ◽  
Author(s):  
Eugene W MacDonald
Keyword(s):  
New Species ◽  
Type Species ◽  
New Genus ◽  
Intermediate Position ◽  
Arctic Canada ◽  
Lower Silurian ◽  
The Family ◽  
Cape Phillips Formation ◽  
Cornwallis Island

Radiolaria of the family Palaeoscenidiidae were recovered from two bedded-limestone and two limestone-concretion samples from the upper Llandovery of the Cape Phillips Formation, Cornwallis Island, Arctic Canada. The new genus Insolitignum is defined by two apical rays, three basal rays, and a principal ray in an intermediate position. The principal ray distinguishes this genus from Palaeoephippium. Insolitignum dissimile, the type species of the new genus, was previously placed in Palaeoephippium. New species described here are Insolitignum peranima, Insolitignum vivanima, and Palaeoephippium adraini.

Llandovery secuicollactinae and rotasphaeridae (radiolaria) from the Cape Phillips Formation, Cornwallis Island, Arctic Canada

1998 ◽  
Vol 72 (4) ◽  
pp. 585-604 ◽  
Author(s):  
Eugene W. MacDonald
Keyword(s):  
New Species ◽  
New Genus ◽  
Arctic Canada ◽  
Cape Phillips Formation ◽  
Cornwallis Island ◽  
Lattice Shells

Radiolaria extracted from two bedded-limestone and two limestone-concretion samples from the upper Llandovery of the Cape Phillips Formation, Cornwallis Island, allow the distinction between the spicular haplentactinid subfamily Secuicollactinae and the nonspicular Rotasphaeridae. This restores Secuicollactinae and returns Secuicollacta to the subfamily from the Rotasphaeridae. Secuicollactinae represent 36 percent of the fauna and are assigned to three genera, Secuicollacta, Diparvapila new genus, and Parvalanapila new genus; these form 27, five, and three percent of the fauna, respectively. The remaining one percent of the subfamily is unassigned. Rotasphaeridae form four percent of the fauna and are represented by Rotasphaera. Secuicollacta is diagnosed on the basis of the presence of an ectopic spicule in addition to several rotasphaeridlike primary units. The salient characters of Diparvapila include two lattice shells with an ectopic spicule on the medullary shell. Parvalanapila is diagnosed on the basis of a lattice sphere overlain by a labyrinthine layer and an ectopic spicule on the lattice sphere. New species described here are Secuicollacta malevola, S. sceptri, S. gliris, S. herrimani, S. segari, S. vallipuellae, S. resodiosae, S. glaebosa, S. teli, Diparvapila hicocki, D. saintrochae, D. larseni, Parvalanapila fleischerorum, and Rotasphaera severa. Four species of Secuicollacta are reported in open nomenclature, as are two of Diparvapila and two of Rotasphaera.

Graptolites of the genus Mediograptus Bouček and Přibyl from the uppermost Llandovery of Cornwallis Island, Arctic Canada

1997 ◽  
Vol 34 (6) ◽  
pp. 765-769 ◽  
Author(s):  
David K. Loydell ◽  
John Mckenniff ◽  
Alfred C. Lenz
Keyword(s):  
The Other ◽  
Arctic Canada ◽  
Cape Phillips Formation ◽  
Cornwallis Island

Isolated specimens of three species of Mediograptus are described from latest Llandovery (Telychian) strata of the Cape Phillips Formation, Cornwallis Island. One species is new, Mediograptus? bicercis n.sp., whereas the other two, Mediograptus flittoni and Mediograptus morleyae, have previously been recorded only from the Telychian of Wales. A possible paleolatitudinal control on mediograptid distribution is suggested, with one suite of taxa characterizing higher paleolatitudes (Bohemia), the other, including the species described herein, lower paleolatitudes (Wales, Arctic Canada). The diagnosis for the genus Mediograptus is emended.

Microvertebrate assemblages from the Upper Silurian of Cornwallis Island, Arctic Canada

1999 ◽  
Vol 36 (3) ◽  
pp. 349-361 ◽  
Author(s):  
Carole J Burrow ◽  
Jo MJ Vergoossen ◽  
Susan Turner ◽  
Tom T Uyeno ◽  
Ray Thorsteinsson
Keyword(s):  
New Species ◽  
Arctic Canada ◽  
Growth Zones ◽  
Upper Silurian ◽  
The Baltic ◽  
Cornwallis Island

Microvertebrate assemblages from four Upper Silurian (?Ludlow-Pridoli) localities on Cornwallis Island, Arctic Canada, comprise mainly scales, plus dentition cones and jaw fragments from ischnacanthid acanthodians, with rare scales assigned to heterostracan Lepidaspis? sp., ?chondrichthyan Arauzia? sp., and Placodermi? gen. et sp. indet. Most of the scales in sample C-11460 are assigned to the poracanthodid acanthodian Poracanthodes canadensis sp.nov., which shows closest affinity to Poracanthodes punctatus Brotzen variants from the Baltic Pridoli. The flank scales of the new species resemble those of P. punctatus s.s. (Silurian variant; the zone fossil for the late Pridoli in the Standard Silurian microvertebrate scheme), with their superposed crown growth zones, rows of small pores aligned with the underlying zones, number of radial canals, and "arcade" canals connecting these radial canals. They differ in having numerous anterior crown riblets, "zig-zag" rather than straight crown pore rows, and V-shaped arcade canals.

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