2006 Philadelphia Annual Meeting (2225 October 2006)
Paper No. 178-8
Presentation Time: 1:30 PM-5:30 PM


FELDMAN, Howard R., Division of Paleontology (Invertebrates), American Museum of Natural History, New York, NY 10024, feldspar4@optonline.net, BOUCOT, Arthur J., Department of Zoology, Oregon State Univ, Corvallis, OR 97331, SMOLIGA, John A., 9 Chickadee Lane, Brookfield, CT 06804, and WILSON, Mark A., Department of Geology, The College of Wooster, Wooster, OH 44691

An exposure of the Middle to Upper Ordovician Martinsburg Formation in a shale pit on the Mohonk Preserve, southeastern New York, consists of predominantly dark gray shales and siltstones interbedded with fine grained graywacke beds, occasional prominent pyrite layers and disseminated sphalerite, chalcopyrite and galena. Carbonaceous material occurs mostly as fine-grained patches throughout the matrix. The studied section is tectonically stressed with shiny quartz slickensided surfaces, parallel cross-laminated strata and ripple marks. Crinoid stems, some slightly disarticulated, and free columnals occur on different bedding surfaces indicating a possible change in current regime. Scattered linear to sinusoidal horizontal burrow structures ranging in diameter from .5-3 cm are found on the silty beds. Some of the burrows are infilled with coarse quartz grains. The faunal constituents include brachiopods (93%), crinoids (3%), bivalves (3%), ostracodes (<1%), corals (<1%) and unidentified burrowers (<1%). The brachiopods are represented by a low diversity assemblage of dalmanellids and what appears to be a new species of Sowerbyella. The fauna can be classified into distinct trophic groups: (1) high-level suspensions feeders (crinoids, corals); (2) low-level suspension feeders (brachiopods, bivalves); (3) animals that collect food from the sediment surface (ostracodes); and (4) animals that feed within the sediment (burrowers). This partition of feeding niches leads to a reduced competitive trophic structure and therefore increased community stability.

2006 Philadelphia Annual Meeting (2225 October 2006)
General Information for this Meeting
Session No. 178--Booth# 150
Fossil Behavior (Posters): In Honor of Adolf Seilacher
Pennsylvania Convention Center: Exhibit Hall C
1:30 PM-5:30 PM, Tuesday, 24 October 2006

Geological Society of America Abstracts with Programs, Vol. 38, No. 7, p. 436

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