scholarly journals Solitary rugose corals of the Selkirk member, Red River formation (late middle or upper ordovician), southern Manitoba

1981 ◽  
Author(s):  
R J Elias
Keyword(s):  
Red River ◽  
Upper Ordovician ◽  
Rugose Corals

Solitary Rugose Corals of the Upper Ordovician Montoya Group, Southern New Mexico and Westernmost Texas

1985 ◽  
Vol 59 (S16) ◽  
pp. 1-58 ◽  
Author(s):  
Robert J. Elias
Keyword(s):  
New Mexico ◽  
North America ◽  
High Energy ◽  
Low Energy ◽  
Red River ◽  
Energy Conditions ◽  
Upper Ordovician ◽  
Rugose Corals ◽  
Solitary Coral ◽  
Mountain Province

The Upper Ordovician (middle Edenian to upper Richmondian) Montoya Group of southern New Mexico and westernmost Texas comprises, in ascending order, the Second Value Dolomite, Aleman Formation, and Cutter Dolomite. Solitary rugose corals in the Second Value are Grewingkia robusta (Whiteaves, 1896), Bighornia sp. cf. B. patella (Wilson, 1926), Streptelasma divaricans (Nicholson, 1875), a new species of Neotryplasma, and Salvadorea? spp. A and B. Salvadorea kingae kingae Nelson, 1981, G. franklinensis n. sp., and G. crassa alemanensis n. subsp. occur in the Aleman. Taxa found in the Cutter are S. kingae cutterensis n. subsp., G. sp. cf. G. franklinensis, and B. sp. cf. B. patella.Grewingkia robusta is the most abundant species in the solitary rugosan assemblage that is present within the Second Value. This assemblage apparently inhabited comparatively deep-water environments. Most of the corals lived in relatively high-energy conditions, but epizoic forms favored low-energy niches. Salvadorea kingae is the most common taxon in the assemblage that characterizes the Aleman-Cutter. This is probably a comparatively shallow-water assemblage. The dominant taxon inhabited relatively low-energy environments, while less common species lived in higher energy conditions. If the distribution of solitary rugose corals in the area of Montoya deposition was related primarily to water depth, a paleobathymetric gradient from relatively deep in the west to predominantly shallow in the southeast existed through Second Value–Aleman time. During Cutter time, water was relatively deep in the southwest and northeast, and predominantly shallow in the southeast. If the degree of environmental restriction was the principal factor limiting the distribution of Montoya solitary Rugosa, open normal marine environments were predominant in the southeast and uncommon in the north and west.Montoya representatives of Grewingkia, Bighornia, and Salvadorea indicate that the area of deposition was situated within the Red River–Stony Mountain Solitary Coral Province, which occupied most of North America during Late Ordovician time. All species of these genera are typical “epicontinental” forms. Neotryplasma, the only “continental margin” taxon, reflects a cratonic margin paleoposition. The discovery of Streptelasma divaricans within Edenian-Maysvillian strata in the Montoya is consistent with an hypothesis that solitary Rugosa were introduced to the Richmond Solitary Coral Province of eastern North America during an early Richmondian transgression.Within the Red River–Stony Mountain Province, geographic speciation and dispersion seem to have been important factors in the evolution and diversification of Grewingkia robusta and related taxa, including G. haysii selkirkensis n. subsp. from the Selkirk Member of the Red River Formation in southern Manitoba. In Salvadorea, speciation events within the New Mexico–Texas area and Williston Basin were apparently rapid, and coincided with onsets of clastic deposition. Evolutionary change within this genus has not been recognized in the Hudson Bay Basin, where there were no clastic influxes.In the Aleman-Cutter sequence of the Montoya Group, recognition of specific intervals bearing solitary rugose corals may permit detailed biostratigraphic, and possibly chronostratigraphic, correlation. The change from a Grewingkia-dominated assemblage to a Salvadorea-dominated assemblage was not synchronous throughout the Red River–Stony Mountain Province, and the ranges of widely distributed species such as G. robusta and S. kingae cannot be considered isochronous from basin to basin. Within particular basins, endemic taxa having restricted stratigraphic ranges, such as G. crassa alemanensis, can be useful biostratigraphic markers. Streptelasma divaricans remains useful as a Richmondian index fossil in strata within the area occupied by the Richmond Province.

Borings in solitary rugose corals of the Selkirk Member, Red River Formation (late Middle or Upper Ordovician), southern Manitoba

1980 ◽  
Vol 17 (2) ◽  
pp. 272-277 ◽  
Author(s):  
Robert J. Elias
Keyword(s):  
Relative Abundance ◽  
Red River ◽  
Marine Environments ◽  
Upper Ordovician ◽  
Shallow Marine ◽  
Rugose Corals

Borings occur in solitary rugose corals from the Selkirk Member of the late Middle or Upper Ordovician Red River Formation in southern Manitoba. They are assigned to Dictyoporus garsonensis n. ichnosp., which was produced by algae, and Trypanites weisei Mägdefrau 1932, made by spionid polychaete annelids. Most, and possibly all, boring occurred while the host corals were alive and in life position. The location and relative abundance of borings support interpretations that unattached curved solitary corals lay with the convex cardinal side in the sediment and the concave counter side facing upward during life, whereas straight conical forms were oriented upright in the sediment. These ichnospecies suggest that host corals lived in very shallow marine environments.

Upper Ordovician conodonts, brachiopods, and chronostratigraphy of the Whittaker Formation, southwestern District of Mackenzie, N.W.T., Canada

1989 ◽  
Vol 26 (1) ◽  
pp. 74-87 ◽  
Author(s):  
Charles E. Mitchell ◽  
Walter C. Sweet
Keyword(s):  
United States ◽  
Common Ancestor ◽  
Red River ◽  
The Arctic ◽  
Upper Ordovician ◽  
Standard Section ◽  
The Common ◽  
Cincinnatian Series

Ten samples from a 160 m section through the lower Whittaker Formation yielded Red River Province conodonts as well as a shelly macrofossil assemblage representing the "Arctic Ordovician fauna." Both the microfossils and macrofossils have strong affinities with taxa represented in strata of Cincinnatian age in the western Midcontinent Province of North America.Conodont-based graphic correlation of section W-1 with a Composite Standard Section developed for midcontinental United States indicates that the lower Whittaker Formation on the east flank of the Redstone Arch represents nearly the entire Cincinnatian Series. Trilobites of the Ceraurus mackenziensis Zone occur in strata correlative with the upper Edenian and those of the Whittakerites planatus Zone first appear at or just below the projected base of the Maysvillian Stage. The age of the Ceraurinella necra Zone is still uncertain but is likely to be early Edenian.Thaerodonta recedens (Sardeson) and other elements of the Bighornia – Thaerodonta fauna also debut in uppermost Edenian or lowermost Maysvillian strata. The morphology of Sowerbyella redstonensis n.sp. and Thaerodonta recedens from the lower Whittaker Formation indicates that the common ancestor of early Thaerodonta species may have arisen during latest Edenian time. The first appearance of Thaerodonta may constitute a useful biostratigraphic datum throughout the Red River Province. The strongly Thaerodonta-like species, Sowerbyella redstonensis n.sp., is described from silicified material of mid-Edenian age.

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