The fossils we have collected for this study are mostly bits and pieces of eggshells rather than bones or teeth. If you look hard enough in sand dune areas, you can find 1 cm. sized pieces laying on the top of the sand. After we collect them and they are returned to the lab at the University of Colorado, they are cleaned by dissolving the outer coat in an acid solution. Eggshells are made mostly of carbonate, so they fizz for a minute, before we rinse them in distilled water to stop the fizzing.
After this step, we use a grinding tool to take off the outer eggshell layers. At this point, the eggshell is a nice pale beige color and you can barely see the little pores on the surface. Three types of analysis are done next: 1) A little tiny piece is sent to a special Radiocarbon laboratory to determine its age; 2) A 2nd piece is dissolved in acid and dated by amino acid racemization dating; 3) A 3rd piece is sent to the Lab at the Carnegie Institution in Washington, D.C. to analyze the stable isotopes with a mass spectrometer. When all the data has been collected, a data table is made with the location of where we found it, a sample code, a radiocarbon age, an amino acid date, and the stable isotope measurements.
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