Martina Bennick, 2019 EGGS alumni and current biology graduate student, was selected as one of two student poster presentation winners in the Geobiology and Geomicrobiology Division at the Geological Society of America 2019 annual meeting in Phoenix, Arizona.
Her poster, entitled “Determining The Origin Of Intracameral Deposits In The Orthocerid Genus Arionoceras” presented research she conducted with Dr. Cindy Venn and Dr. Adrian Van Rythoven of the EGGS department, which was an outgrowth of a senior research project supervised by Dr. Alan Gishlick, also of the EGGS department.
Martina’s project focused on determining to what extent intracameral deposits were formed through biomineralization versus post-mortem diagenetic alteration. She first sliced the specimens longitudinally and treated one half with dilute acid to differentiate the internal layering, clearly visible under a high powered dissecting microscope. She then made a thin section of one of the specimens to examine with a cathodoluminoscope to establish chemical differences between the layers. Another etched specimen was examined using a portable scanning electron microscope. Two distinct internal layers were observed: an outer complex layer that she inferred to be from biodeposition during life, and an internal layer of sparry calcite consistent with what would be expected from chamber filling after burial.
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