Radiocarbon Dating of Fossil Eggshell

Controlled feeding experiments demonstrate that the 14 C content of the carbonate fraction of fossil avian eggshell should reliably reflect the 14 C activity of feed and contemporary atmospheric CO 2 regardless of amounts of 14 C depleted scratch injested. Consideration of biochemical pathways and exchange rates across lung membranes leads to the possibility that the carbonate fraction may, in some instances, be slightly 14 C depleted. 14 C dates on eggshell carbonate should require little or no correction. As with marine shell carbonate, normal soil-forming processes may alter the surficial carbon isotopes in eggshell carbonate. 14 C dates on the protein fraction should be even more reliable than those on the carbonate fraction, but only if special precautions or separation techniques exclude non-indigenous carbon from the sample. Original protein contents are likely to be too low for conventional 14 C dating techniques.