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Title:More Than Meets the Eye: Cathodoluminescence Analysis of a Fossil Tooth
Author(s):Larmon, Jean
Contributor(s):Ambrose, Stanley; Fried, Glenn; Fouke, Bruce; McDonald, Greg; Lucero, Lisa
Abstract:Cathodoluminescence microscopy employs an X-ray electron beam to stimulate visible light where distinct minerals are concentrated within a material. It is often used to understand fossilization processes and identify uncontaminated specimens suitable for biogeochemical analyses. Pictured here is a cross-section of an extinct giant sloth (Eremotherium laurillardi) tooth recovered from a cenote (water-filled sinkhole) in central Belize. The reflected light image (left) shows a thick layer of vasodentine (top), a thin layer of dense orthodentine (middle), and porous cementum (bottom). Bright orange areas (right) appear where the tooth has been invaded by calcium carbonate (calcite); blue indicates silicification. Orthodentine is uncontaminated, except for cracks filled with calcite crystals. Uncontaminated orthodentine can be used for dating and stable isotopic analysis. Stable carbon and oxygen isotope ratios of 20 orthodentine microsamples along the growth axis show moderate seasonal variation in climate, reflecting variation in water stress of the C3 plants that the sloth consumed. At the end of the last Ice Age, when many megafauna went extinct, this gigantic sloth, standing six meters tall, likely descended into the steep sided cenote for a drink during a dry season and became trapped; Its remains were recovered by divers thousands of years later.
Issue Date:2016-04
Rights Information:Copyright 2016 Jean Larmon
Date Available in IDEALS:2016-04-14

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