Some disparid crinoids from the Upper Ordovician (Shermanian) Walcott-Rust quarry of New York

2008 ◽  
Vol 82 (1) ◽  
pp. 57-77 ◽  
Author(s):  
James C. Brower
Keyword(s):  
New York ◽  
Deep Water ◽  
Upper Ordovician ◽  
Food Items ◽  
Wide Range ◽  
Food Particles ◽  
Anal Sac ◽  
Long Stem ◽  
Distal Stem

locrinus trentonensis Walcott, 1883 is characterized by the widest food grooves and the largest covering plates of any of the Walcott-Rust Quarry crinoids, which indicates that the animal captured relatively large food particles with large and widely separated tubefeet. Although iocrinids are generally considered as primitive disparids, their anal sac is unique. the holdfasts of I. trentonensis consist of distal stem coils that are tightly wrapped around the columns of other crinoids. the relatively long column of Ectenocrinus simplex (Hall, 1847) was attached to a wide range of shelly substrates by a small irregular and somewhat lobate holdfast. Ectenocrinids ate much smaller food items that were collected by smaller and more tightly packed tubefeet. the ontogeny of E. simplex illustrates the differences between the food gathering systems of conspecific crinoids from shallow and deep water habitats. the calceocrinid Calceocrinus barrandii Walcott, 1883 lived with its long stem forming a runner along the seafloor. the crown was movably hinged to the basal circlet and the stem. Moderately wide food grooves were probably present.

Camerate and Cladid crinoids from the Upper Ordovician (Katian, Shermanian) Walcott-Rust Quarry of New York

2010 ◽  
Vol 84 (4) ◽  
pp. 626-645 ◽  
Author(s):  
James C. Brower
Keyword(s):  
New York ◽  
Upper Ordovician ◽  
Attachment Structures ◽  
Soft Objects ◽  
Food Particles ◽  
Anal Sac ◽  
Long Stem ◽  
Distal Stem ◽  
Attachment Devices ◽  
Stem Segments

The camerates, Pycnocrinus argutus (Walcott, 1883) and Rhaphanocrinus subnodosus (Walcott, 1883), are characterized by narrow food grooves. An open distal stem coil was present in P. argutus, and R. subnodosus may have possessed the same type of holdfast. Such holdfasts either lay loose on the seafloor or were wrapped around unknown soft objects. The rhaphanocrinids were located at elevations of at least 300 mm above the substrate. Conversely, the much smaller pycnocrinids lived close to the seafloor at levels of about 10 to 24 mm. The three cladids are Merocrinus curtus (Ulrich, 1879), M. retractilis (Walcott, 1883), and Dendrocrinus gregarius Billings, 1857a. Merocrinus typus Walcott, 1883 and M. corroboratus Walcott, 1883 are conspecific with M. curtus. The spiral anal sac of M. retractilis is unique. Embryocrinus problematicus Hudson, 1918 probably represents a juvenile of Dendrocrinus gregarius, which also occurs in Ottawa, Ontario. Complete columns and attachment structures have not been found for D. gregarius and Merocrinus retractilis. Merocrinus curtus ranges from New York into the Cincinnati, Ohio area of the midcontinent. Although attachment devices and long stem segments are not preserved in the New York specimens, individuals of Merocrinus curtus from Cincinnati either have a conical holdfast cemented to a bryozoan or a tight distal stem coil that was wrapped around the stem of another crinoid; adult merocrinids from the Cincinnati region were positioned high above the seafloor, and incomplete stem segments up to about 800 mm long are known. The Walcott-Rust Quarry cladids all possessed wider food grooves than the camerates, so they were able to catch larger food particles.

Paleoecology of suspension-feeding echinoderm assemblages from the Upper Ordovician (Katian, Shermanian) Walcott-Rust Quarry of New York

2011 ◽  
Vol 85 (2) ◽  
pp. 369-391 ◽  
Author(s):  
James C. Brower
Keyword(s):  
New York ◽  
Turbidity Currents ◽  
Maximum Height ◽  
Suspension Feeding ◽  
Upper Ordovician ◽  
Structure Comparison ◽  
Food Items ◽  
Wide Range ◽  
Soft Objects ◽  
Food Particles

The Walcott-Rust Quarry echinoderm fauna lived at the base of a carbonate ramp in moderately deep water (Benthic Assemblage 5 of Boucot and others) below wave base for all or most storms but within the photic zone. The inhabitants of the soft substrate were buried rapidly by distal carbonate turbidity currents or mudflows. Because of the episodic sedimentation, the organisms were opportunistic. The suspension-feeding echinoderms include nine crinoids, a rhombiferan, and a paracrinoid. They occur with a variety of filter-feeding bryozoan colonies, a few brachiopods, and numerous trilobites. Most suspension-feeding echinoderms were attached by small holdfasts to hard shelly substrates. Some of these substrates lay on the seafloor, whereas others may have been elevated when the larvae settled. Other types of holdfasts are distal stems that are tightly and permanently coiled around crinoid stems, open distal stem coils that lay on the substrate or were wrapped around soft objects, and recumbent stems running along the seafloor. The echinoderms occupied levels from the seafloor to almost a meter above it, whereas the bryozoans and brachiopods ranged from the seabed to a maximum height of about 10 cm. The sizes of the echinoderm food grooves and comparisons with their modern analogues along with filtration theory indicate that they ate food particles that were mostly larger than those taken by bryozoans. In general, the different taxa of suspension-feeding echinoderms living at the same elevation above the seafloor collected food particles of different maximum sizes and different mean sizes; however, they overlapped greatly with respect to smaller food items. The various crinoid species were able to feed at different ranges of ambient current velocities, which also tended to separate them ecologically. Crinoids having narrow food grooves were restricted to feeding on small food particles but they caught food items over a wide range of current velocities; the converse is also true, which suggests an evolutionary or behavioral tradeoff. As in most Ordovician crinoid communities, predation was comparatively low. Regenerated arms in crinoids reflect predation on about 1.8% of the individuals in the fauna and the most likely fossilized culprits are trilobites and straight nautiloids. Competition for space and attachment sites within and between species of the Walcott-Rust Quarry crinoid and rhombiferan assemblages does not seem to have been significant in regulating their ecological structure. Comparison with shallow-water crinoid assemblages of roughly the same age demonstrates that the Walcott-Rust Quarry faunas were less diverse and less complex. This could be caused by one or more of the following conditions that affected the Walcott-Rust fauna: lower average current velocities, the episodic sedimentological disturbances, higher suspended sediment content in the water, and softer substrates.

Paleoecology of echinoderm assemblages from the Upper Ordovician (Katian) Dunleith Formation of northern Iowa and southern Minnesota

2013 ◽  
Vol 87 (1) ◽  
pp. 16-43 ◽  
Author(s):  
James C. Brower
Keyword(s):  
New York ◽  
Carbonate Platform ◽  
Upper Ordovician ◽  
Benthic Assemblages ◽  
Frequency Distributions ◽  
Attachment Structures ◽  
Ecological Complexity ◽  
Food Particles ◽  
Deposit Feeding ◽  
Distal Stem

The Dunleith Formation echinoderms lived on a shallow water carbonate platform (Benthic Assemblages outer 2 and 3 during the latter part of the Dunleith Regressive Cycle). The echinoderms were buried rapidly by storms or a volcanic ash bed in one example. The presence of complete specimens, entire crowns, attachment structures, and excellent preservation strongly suggests that these assemblages reflect in situ communities on the seafloor that have not been significantly mixed, transported, or concentrated in time. Most taxa are suspension feeders, namely 21 crinoids, one glyptocystitid rhombiferan, a paracrinoid, and two edrioasteroids, but a deposit feeding pleurocystitid rhombiferan is also common. Three assemblages are recognized and defined by their dominant taxa; in order of increasing depth, these are theCotylacrinna sandra,Pleurocystites strimplei, andCupulocrinus crossmaniassemblages. Substrates ranged from hard- or firm-ground carbonates to soft carbonate and siliciclastic muds. Diverse attachment structures are recognized: the recumbent stems of calceocrinids, lichenocrinids on shells, small distal stem tips, and round to lobate calcite pads cemented to shells or the substrate, open distal stem coils directly on the seabed or coiled around soft objects thereon, and large conical and highly modified cirrus holdfasts on hard- or firm-grounds. The echinoderms were located at levels ranging from the seafloor to almost a meter above, with maximum diversity at about 50 mm above the seafloor. The size frequency distributions of food particles and the ranges of ambient current velocities for successful feeding by the juveniles and adults of the common crinoids are modeled using filtration theory. The food particle size distributions and the current velocities for feeding are correlated with the arm or filtration fan morphology of the crinoids. Differences between these parameters tend to partially separate the feeding ecologies of species located at the same elevation. Nevertheless, considerable overlap remains between species for small sized food particles and the lower ranges of ambient current velocities for feeding. Except for theCotylacrinna sandraAssemblage, competition for space does not seem to have been important in regulating the ecological structure of the Dunleith crinoids. However, the deposit feeding pleurocystitids possibly competed for food and space in one example. The Dunleith assemblages are much more diverse with greater ecological complexity than seen in the relatively deep water fauna from the Upper Ordovician Trenton Group of the Walcott-Rust Quarry in New York (Benthic Assemblage 5).

Cupulocrinid crinoids from the Middle Ordovician (Galena Group, Dunleith Formation) of northern Iowa and southern Minnesota

1992 ◽  
Vol 66 (1) ◽  
pp. 99-128 ◽  
Author(s):  
James C. Brower
Keyword(s):  
Niche Differentiation ◽  
Upper Ordovician ◽  
Average Width ◽  
Positive Allometry ◽  
Middle Ordovician ◽  
Surrogate Variable ◽  
Crown Volume ◽  
Food Particles ◽  
Anal Sac ◽  
Food Groove

Two cupulocrinids,Cupulocrinus crossmanin. sp. andPraecupulocrinus conjugans(Billings) n. gen., are known from the Middle Ordovician (Galena Group, Dunleith Formation) of northern Iowa and southern Minnesota. Various morphologic and ontogenetic features demonstrate thatPraecupulocrinusis more primitive thanCupulocrinus. The two species commonly occur together. In addition, both taxa coexisted at similar levels with stem lengths ranging from about 1.5 cm in juveniles to 15 cm in adults. Relatively complete growth sequences illustrate growth and variation and show how two related crinoids subdivided feeding niches. The crown volume provides a satisfactory surrogate variable for the size of the animal. The food-gathering system of the cupulocrinids is mainly augmented by the addition of new plates at the ends of the arms. The number of plates in the arms and the arm length exhibit positive allometry relative to crown volume, largely due to development of new branches at the arm tips. The food-gathering capacity equals the number of food-catching tube-feet multiplied by the average width of the food grooves. Food-gathering capacity is also positively allometric with respect to crown volume and the amount of tissue that must be supplied with food. Consequently, the ratio of food-gathering capacity:crown volume is either constant or declines slightly with increasing size and age. The food groove width increases throughout ontogeny so adult crinoids ate larger food particles than juveniles.Praecupulocrinus conjugans(Billings) n. gen. has more narrow food grooves thanCupulocrinus crossmanin. sp. of comparable size and age, which suggests niche differentiation based on food-particle size. The arm and tube-foot geometry indicates that both cupulocrinids utilized the same type of suspension feeding.The morphology of the anal sac and the lack of “patelloid” processes in the arms indicate thatCupulocrinus sepulchrumRamsbottom from the Upper Ordovician of Scotland belongs toDendrocrinus.

The application of filtration theory to food gathering in Ordovician crinoids

2007 ◽  
Vol 81 (6) ◽  
pp. 1284-1300 ◽  
Author(s):  
James C. Brower
Keyword(s):  
Behavioral Changes ◽  
Filtration Theory ◽  
Upper Ordovician ◽  
Nutrient Contents ◽  
Particle Distributions ◽  
Wide Range ◽  
Ecological Patterns ◽  
Food Particles ◽  
Mean Size ◽  
Tube Feet

Food gathering of some adult Upper Ordovician crinoids was modeled by means of filtration theory. The arm-branching patterns of the 13 species examined range from nonpinnulate isotomous arms to uniserial and biserial arms with numerous pinnules. Most taxa are roughly equivalent with respect to ambient current velocities and the nutrient contents needed from seawater. Two species with extensively branched arms have markedly higher nutritional requirements at any one ambient current velocity. The results are somewhat correlated with environment in the form of differential current velocities, water flow patterns, and food abundance and composition. The data are generally compatible with filtration theory and the environmental distributions of many Ordovician and other Paleozoic crinoids, and they reveal that Upper Ordovician crinoids had at least partially developed the ecological patterns seen in later Paleozoic crinoids. Various morphological, physiological, and behavioral changes can be employed by crinoids to alter their nutritional balance. The size distributions of food particles that are caught by the crinoids are modeled. These food particle distributions for the Ordovician fossils resemble those of modern crinoids. Relative to the population of food items, the distributions of particles that are trapped are shifted towards larger items because the crinoid filtration nets are more efficient at catching larger particles. Crinoids with relatively open filtration nets and large food-catching tube feet are generalized and feed on a wide range of food particles of a relatively large mean size. The more specialized taxa with extensively branched arms bearing small and closely packed food-catching tube feet are restricted to a more narrow range of smaller food particles.

Charles Olson and American Modernism

2018 ◽  
Author(s):  
Mark Byers
Keyword(s):  
New York ◽  
Political Action ◽  
The Self ◽  
Instrumental Reason ◽  
Charles Olson ◽  
American Modernism ◽  
Avant Garde ◽  
Wide Range ◽  
American Poet ◽  
Mark Rothko

The Practice of the Self situates the work of American poet Charles Olson (1910–70) at the centre of the early postwar American avant-garde. It shows Olson to have been one of the major advocates and theorists of American modernism in the late 1940s and early 1950s; a poet who responded fully and variously to the political, ethical, and aesthetic urgencies driving innovation across contemporary American art. Reading Olson’s work alongside that of contemporaries associated with the New York Schools of painting and music (as well as the exiled Frankfurt School), the book draws on Olson’s published and unpublished writings to establish an original account of early postwar American modernism. The development of Olson’s work is seen to illustrate two primary drivers of formal innovation in the period: the evolution of a new model of political action pivoting around the radical individual and, relatedly, a powerful new critique of instrumental reason and the Enlightenment tradition. Drawing on extensive archival research and featuring readings of a wide range of artists—including, prominently, Barnett Newman, Mark Rothko, David Smith, Wolfgang Paalen, and John Cage—The Practice of the Self offers a new reading of a major American poet and an original account of the emergence of postwar American modernism.

scholarly journals Dialogic & Critical Pedagogies: An Interview with Ira Shor

2017 ◽  
Vol 5 ◽  
Author(s):  
Ira Shor ◽  
Eugene Matusov ◽  
Ana Marjanovic-Shane ◽  
James Cresswell
Keyword(s):  
New York ◽  
Critical Pedagogy ◽  
Critical Literacy ◽  
Paulo Freire ◽  
Central Feature ◽  
Community Members ◽  
Dialogic Pedagogy ◽  
Language And Thought ◽  
Wide Range ◽  
Critical Pedagogies

In 2016, the Main Editors of Dialogic Pedagogy Journal issued a call for papers and contributions to a wide range of dialogic pedagogy scholars and practitioners. One of the scholars who responded to our call is famous American educator Ira Shor, a professor at the College of Staten Island, City University of New York. Shor has been influenced by Paulo Freire with whom he published, among other books, “A Pedagogy for Liberation” (1986), the very first “talking book” Freire did with a collaborator. His work in education is about empowering and liberating practice, which is why it has become a central feature of critical pedagogy.Shor’s work has touched on themes that resonate with Dialogic Pedagogy (DP). He emphasises the importance of students becoming empowered by ensuring that their experiences are brought to bear. We were excited when Shor responded to our call for papers with an interesting proposal: an interview that could be published in DPJ, and we enthusiastically accepted his offer. The DPJ Main Editors contacted the DPJ community members and asked them to submit questions for Ira. The result is an exciting in-depth interview with him that revolved around six topics: (1) Social Justice; (2) Dialogism; (3) Democratic Higher Education; (4) Critical Literacy versus Traditional Literacy; (5) Paulo Freire and Critical Pedagogy; and (6) Language and Thought. Following the interview, we reflect on complimentary themes and tensions that emerge between Shor’s approach to critical pedagogy and DP.

Maturation thermique et histoire de l'enfouissement et de la génération des hydrocarbures du bassin de l'archipel de Mingan et de l'île d'Anticosti, Canada

1990 ◽  
Vol 27 (6) ◽  
pp. 731-741 ◽  
Author(s):  
Rudolf Bertrand
Keyword(s):  
Carbonate Platform ◽  
Burial History ◽  
Upper Ordovician ◽  
Southeastern Part ◽  
Middle Ordovician ◽  
Oil Generation ◽  
Wide Range ◽  
History Of ◽  
Anticosti Island ◽  
Depth Of Burial

Carbonate platform sequences of Anticosti Island and the Mingan Archipelago are Early Ordovician to Early Silurian in age. With the exception of the Macasty Formation, the sequences are impoverished in dispersed organic matter, which is chiefly composed of zooclasts. Zooclast reflectances suggest that the Upper Ordovician and Silurian sequences outcropping on Anticosti Island are entirely in the oil window but that the Lower to Middle Ordovician beds of the Mingan Archipelago and their stratigraphic equivalents in the subsurface of most of Anticosti Island belong to the condensate zone. Only the deeper sequences of the southwestern sector of Anticosti Island are in the diagenetic dry-gas zone. The maximum depth of burial of sequences below now-eroded Silurian to Devonian strata increases from 2.3 km on southwestern Anticosti Island to 4.5 km in the Mingan Archipelago. A late upwarp of the Precambrian basement likely allowed deeper erosion of the Paleozoic strata in the vicinity of the Mingan Archipelago than on Anticosti Island. Differential erosion resulted in a southwestern tilting of equal maturation surfaces. The Macasty Formation, the only source rock of the basin (total organic carbon generally > 3.5%, shows a wide range of thermal maturation levels (potential oil window to diagenetic dry gas). It can be inferred from the burial history of Anticosti Island sequences that oil generation began later but continued for a longer period of geologic time in the northeastern part than in the southeastern part of the island. Oil generation was entirely pre-Acadian in the southern and western parts of Anticosti Island, but pre- and post-Acadian in the northern and eastern parts.

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