Taphonomy and Paleoecological Significance of a Living Fossil: The Lingulid Brachiopod Glottidia palmeri

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Flessa 9417054 The taphonomy and ecology of a living fossil, the lingulid brachiopod Glottidia palmeri, will be examined. Lingulid brachiopods are common and paleoecologically significant fossils in nearshore deposits ranging from the Cambrian to the Recent. Their occurrence is often taken to indicate shallow--water, variable salinity environments. Large populations of the lingulid Glottidia inhabit the intertidal flats of the Colorado River delta. These populations present a rare opportunity to examine the environmental factors controlling this species, the significance of growth--banding in the shell, and the post-mortem processes that affect the preservation and paleoenvironmental interpretation of lingulid fossils. Samples will be collected from along two shore-perpendicular transects: one from mudflats, the other from sandflats. These data will be used to estimate the correspondence between live populations and their shelly remains, and the effects of substrate on morphology and taphonomy. Taphonomic analysis will reveal the extent to which taphonomic features can be used as paleoenvironmental indicators. Field and laboratory experiments will assess the patterns and rates of post-mortem alteration during burial and transport. The environmental significance of disturbance--rings in the shells will be evaluated both by monitoring individual growth and through correlating banding patterns with meteorological and tidal records. Patterns of seasonality or predation recorded in lingulid growth--banding can prove useful in studies of fossil lingulids. This study will be the first comprehensive study of the taphonomy of a representative of this common and geologically useful group. Our results will affect existing interpretations of lingulid--bearing rocks and will greatly enhance the paleoenvironmental utility of fossils of this long-ranging order.