Paleoecological succession leading to a late Ordovician biostrome on Manitoulin Island, Ontario

1978 ◽  
Vol 15 (12) ◽  
pp. 1987-2005 ◽  
Author(s):  
Paul Copper ◽  
David J. Grawbarger
Keyword(s):  
Late Ordovician ◽  
Thick Section ◽  
Short Term ◽  
Bottom Community ◽  
Fossil Assemblage ◽  
Current Action ◽  
Rugose Coral ◽  
Shallow Subtidal ◽  
Laminar Current ◽  
Tabulate Corals

A 4 m thick section in the late Ordovician sequence on Manitoulin Island revealed four successively shallowing carbonate environments, each with a distinctive fossil assemblage. The lowermost quieter water, muddy level bottom community was dominated by the brachiopod Zygospira. Next, increased laminar current action attracted smaller colonies of the tabulate corals Tetradium and Columnopora, and locally small banks of corals and stromatoporoids were built up. In the protected shallow subtidal community following, encrusting algae (Girvanella) and upright match-stick Hedstroemia were more important, alongside Columnopora, cup corals, and a diverse association of thick-shelled bivalves and gastropods. The short-term paleoecological succession terminated under turbulent conditions with large colonies of Labechia, rugose coral colonies of Cyathophylloides, and tabulate corals such as Tetradium forming what is called the Wekwemikong biostrome.

Microborings and growth in Late Ordovician halysitids and other corals

1993 ◽  
Vol 67 (6) ◽  
pp. 922-934 ◽  
Author(s):  
Robert J. Elias ◽  
Dong-Jin Lee
Keyword(s):  
Growth Rate ◽  
Linear Growth ◽  
Inverse Correlation ◽  
Weight Percent ◽  
Late Ordovician ◽  
Coral Growth ◽  
Linear Growth Rate ◽  
Skeletal Density ◽  
Rugose Coral ◽  
Endolithic Algae

Microborings in the Late Ordovician tabulate corals Catenipora rubra (a halysitid) and Manipora amicarum (a cateniform nonhalysitid) and in an epizoic solitary rugose coral differ from nearly all of those previously reported in Paleozoic corals. These microborings were formed within the coralla by endolithic algae and fungi located beneath living polyps. Comparable structures in the Late Ordovician tabulate Quepora ?agglomeratiformis (a halysitid) represent algal microborings, not spicules, and halysitids are corals, not sponges as suggested by Kaźmierczak (1989).Endolithic algae in cateniform tabulates relied primarily on light entering through the outer walls of the ranks rather than through the polyps; lacunae within coralla permitted appropriate levels of light to reach many corallites. The direction of boring was determined by corallum microstructure and possibly also by the distribution of organic matter within the skeleton. There is an apparent inverse correlation between boring activity and coral growth rate.The location and relative abundance of pyritized microborings within calcareous coralla can be established quantitatively and objectively from electron microprobe determinations of weight percent sulfur along appropriate traverses of the coral skeleton. The distribution of such microborings in Catenipora rubra and Manipora amicarum is comparable to algal banding in modern corals; this is the first report of such banding in the interiors of Paleozoic corals. Change in the intensity of boring within each corallum was evidently a response to variation in the linear growth rate of the coral, or to fluctuation in an environmental factor (perhaps light intensity) that could control both algal activity and growth rate in these corals. Change in the algal boring intensity and linear growth rate of the coral was generally but not always seasonal and usually but not invariably associated with change in the density of coral skeletal deposition.Cyclic bands of boring abundance maxima within fossil colonial corals provide a measure of annual linear growth comparable to the widely accepted method based on skeletal density bands. Algal bands are more sporadically developed than density bands within and among coralla, thus increasing the difficulty of interpretation. Fluctuations in the abundance of algal microborings apparently provide a detailed record of changes in the linear growth rate of colonies and of individuals within colonies. Combined analyses of microboring abundance and skeletal density will contribute significantly to our understanding of the biological and environmental factors involved in endolithic activity and coral growth.

Corallite increase in the Late Ordovician coral Agetolites, and its taxonomic implication

2019 ◽  
Vol 93 (5) ◽  
pp. 839-855
Author(s):  
Ning Sun ◽  
Robert J. Elias ◽  
Dong-Jin Lee
Keyword(s):  
South China ◽  
Typical Feature ◽  
Late Ordovician ◽  
Growth Characteristics ◽  
Taxonomic Position ◽  
Phylogenetic Relation ◽  
Axial Mode ◽  
Rugose Corals ◽  
Lateral Mode ◽  
Tabulate Corals

AbstractAgetolites is a problematic Late Ordovician genus possessing traits of both tabulate and rugose corals. The presence of numerous mural pores has often been considered to indicate a relation to tabulates, although an affinity to rugosans has also been proposed, based mainly on well-developed septa that alternate in length. To further consider the taxonomic position of Agetolites, growth characteristics of coralla representing three species from the Xiazhen Formation in South China are documented and assessed, focusing on modes of corallite increase. Three major modes of increase are recognized. By far the most common mode involves the development of an offset from a connective mural pore, without a clear relationship to a particular parent corallite. This mode of increase is usually associated with corner pores, but in one case occurs at a wall pore. The lateral mode of increase, which is relatively uncommon, is a typical feature in corallites along the boundary of intergrowths with stromatoporoids. The axial mode of increase is rare, occurring during rejuvenation of a damaged corallite or during regeneration following termination of a corallite. The mode of corallite increase that is characteristic of Agetolites, involving a connective mural pore and occurring without evidence of a particular parent, supports the interpretation that this genus is not a rugosan or a typical favositid tabulate. Mural pores are unknown in rugosans, and offsets arise from distinct parent corallites in favositids. The Ordovician genus Lichenaria, considered a representative of the most primitive stock of tabulate corals, shows the closest similarities with types of increase in Agetolites. Certain aspects of lateral and axial increase in Agetolites are comparable to features in a few more genera of Ordovician tabulates, further supporting a tabulate affinity. The phylogenetic relation of Agetolites to those and other tabulate genera, however, remains unresolved.

SYMBIOSIS OF RUGOSE CORALS WITH THE CYSTOPORATE BRYOZOAN FISTULIPORA PRZHIDOLENSIS IN THE PRIDOLI (LATEST SILURIAN) OF SAAREMAA, ESTONIA

Palaios ◽  
2020 ◽  
Vol 35 (6) ◽  
pp. 237-244
Author(s):  
OLEV VINN ◽  
ANDREJ ERNST ◽  
MARK A. WILSON ◽  
URSULA TOOM
Keyword(s):  
Late Ordovician ◽  
Growth Surface ◽  
Symbiotic Association ◽  
Negative Effects ◽  
Perpendicular Orientation ◽  
Rugose Corals ◽  
The Relationship ◽  
Tabulate Corals

ABSTRACT In the Silurian, the most common hosts of endobiotic rugose corals were stromatoporoids followed by tabulate corals. Here we describe the relationship between rugose corals and a bryozoan. Solitary rugosans and the cystoporate bryozoan Fistulipora przhidolensis Kopajevich, 1990 formed a symbiotic association in the late Silurian (Pridoli) of Saaremaa, Estonia. The syn vivo nature of the association is indicated by complete intergrowth of both organisms and the perpendicular orientation of the rugosans to the bryozoan growth surface. There are one to seven endobiotic rugosans per bryozoan colony. This is the first detailed study of coral-bryozoan symbiosis from the Silurian; all previous reports describe Late Ordovician, Devonian, or Cenozoic material. The lack of malformations and decrease in the size of bryozoan zooids near the rugosans suggest there were no strong negative effects of the rugosans on the bryozoan. The rugosans likely benefited from their association with the bryozoan, which served as an anchor to stabilize them in hydrodynamically active waters, and the bryozoan may have benefited by protection against some types of predators. The associations described here were most likely mutualistic.

Growth rhythms in the brachiopod Rafinesquina alternata from the Late Ordovician of southeastern Indiana

Paleobiology ◽  
1982 ◽  
Vol 8 (4) ◽  
pp. 389-401 ◽  
Author(s):  
Gary D. Rosenberg
Keyword(s):  
Nutrient Supply ◽  
Growth Increment ◽  
Late Ordovician ◽  
The Moon ◽  
Future Studies ◽  
Growth Increments ◽  
True Number ◽  
Environmental Setting ◽  
Lower Amplitude ◽  
Shallow Subtidal

Growth rhythms are described in the accretionary skeletons of Rafinesquina alternata, a Late Ordovician brachiopod from southeastern Indiana. Contiguous growth increments widen and narrow in repeating series, giving the appearance of adjacent clusters of increments. Fourier analyses of growth increment widths and counts of the number of increments within individual clusters yield similar periodicities. Increments vary in width over a period of approximately 19 increments, modulated with a lower amplitude oscillation of 27 increments. The number of increments per cluster falls into two groups; clusters having between 8 and 17 increments outnumber those having between 18 and 30 increments.All specimens were obtained from a Maysvillian facies of the Dillsboro Formation, previously inferred to represent a shallow subtidal environmental setting. The growth periodicities described here are consistent with this interpretation. The intensity of tidal parameters such as emersion-immersion cycles, substrate shifts, changes in nutrient supply or in oxygen tension declines with depth as would the number of growth increments added each month in response to these factors. Thus, for these specimens, the maximum number of increments per cluster probably approximates the true number of “tidal” days in the Late Ordovician synodic month (period between full moons).The paleoecological model derived from these analyses can be used in future studies to predict the rate of the earth's rotation and the motion of the moon in the Late Ordovician and, equally importantly, to evaluate the limits of uncertainty of such studies.

scholarly journals Sedimentology and paleoecology of Upper Ordovician mounds of Anticosti Island, Quebec

1981 ◽  
Vol 18 (10) ◽  
pp. 1562-1571 ◽  
Author(s):  
John H. Lake
Keyword(s):  
Late Ordovician ◽  
Calcareous Algae ◽  
Upper Ordovician ◽  
Salmon River ◽  
Shallow Subtidal ◽  
Anticosti Island ◽  
Primary Porosity

Relatively thin organic buildups in the Ellis Bay Formation of Anticosti Island developed in a shallow subtidal regressive marine shelf environment during the Late Ordovician. The Ellis Bay Formation has been subdivided into six members by Bolton. Two buildups, one in each of members 4 and 6, were studied in detail. The member 6 mud mound on the Salmon River (8 m thick) is bound by calcareous algae, stromatoporoids, and corals, and consists of a micritic bafflestone core capped by crinoidal lime grainstone. Early marine cementation permeated nearly all of the primary porosity. Cathodoluminescence indicates at least five stages of cementation of the mound. Constructive mound development was terminated by progressively shallowing, agitated marine conditions.The member 4 mound is a small coral (ecological) reef exposed on the Vaureal River.

Stratigraphy of the Upper Ordovician upper Vaureal and Ellis Bay formations, eastern Anticosti Island, Quebec

1987 ◽  
Vol 24 (9) ◽  
pp. 1807-1820 ◽  
Author(s):  
D. G. F. Long ◽  
Paul Copper
Keyword(s):  
Late Ordovician ◽  
Eastern Coast ◽  
Upper Ordovician ◽  
New Members ◽  
Patch Reefs ◽  
Accurate Definition ◽  
Central Regions ◽  
Shallow Subtidal ◽  
Anticosti Island ◽  
Definition Of

Marked facies changes occur in Late Ordovician strata, assigned to the uppermost Vaureal and Ellis Bay formations (Ashgill: Rawtheyan–Hirnantian) on Anticosti Island, Quebec. Western Anticosti features shales and carbonates, whereas outcrops along the eastern coast contain prominent, discontinuous, mixed siliciclastic–carbonate units. Detailed section measurement along the northeast coast allows, for the first time, accurate definition of seven new members within this uninterrupted sequence. Sands present in the upper Vaureal and lower Ellis Bay formations in the east appear to have deterred the growth of muddy-bottom brachiopod communities comparable to those in the western and central regions of Anticosti. Sand units within the upper Vaureal Formation contain 1 m diameter colonies of Paleofavosites; coeval small coral patch reefs are found in the central part of the island, where sands are absent. The uppermost Ellis Bay Formation of northeast Anticosti is marked by a shallow, subtidal, coral–algal oncolite bed or by small (2–4 m across, 1–2 m thick) local coral patch reefs, the tops of which have been used to define the Ordovician – Silurian boundary. No supratidal or intertidal sediments and faunas are evident in the Anticosti succession, suggesting that Late Ordovician sea-level drawdown was insufficient to provide shelf-emergent conditions in this region.

Body size, energetics, and the Ordovician restructuring of marine ecosystems

Paleobiology ◽  
2008 ◽  
Vol 34 (3) ◽  
pp. 342-359 ◽  
Author(s):  
Seth Finnegan ◽  
Mary L. Droser
Keyword(s):  
Body Size ◽  
Relative Abundance ◽  
Late Ordovician ◽  
Depositional Environments ◽  
Data Set ◽  
Widespread Occurrence ◽  
Trade Offs ◽  
Shallow Subtidal ◽  
Ecological Dominance ◽  
Benthic Ecosystems

Major shifts in ecological dominance are one of the most conspicuous but poorly understood features of the fossil record. Here we examine one of the most prominent such shifts, the Ordovician shift from trilobite to brachiopod dominance of benthic ecosystems. Using an integrated database of high-resolution paleoecological samples and body size data, we show that while the average local richness and relative abundance of trilobites declined significantly through the Ordovician, the estimated standing biomass of trilobites, and by implication the amount of energy that they used, remained relatively invariant. This is attributable to an increase in the average body size of trilobite species in our data set, and especially to the widespread occurrence of the exceptionally large Middle-Late Ordovician trilobite genus Isotelus. Brachiopods increase in both mean body size and relative abundance throughout the Ordovician, so that estimates of brachiopod biomass and energetic use increase substantially between the Early and Late Ordovician. Although the data set includes a range of depositional environments, similar trends are observed in both shallow subtidal and deep subtidal settings. These results suggest that diversification of the Paleozoic Fauna did not come at the energetic expense of the Cambrian Fauna. The declining relative abundance of trilobites may reflect a combination of numerical dilution and the necessary energetic trade-offs between body size and abundance.

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