Implications for chloro- and pheopigment synthesis and preservation from combined compound-specific δ&amp;lt;sup&amp;gt;13&amp;lt;/sup&amp;gt;C, δ&amp;lt;sup&amp;gt;15&amp;lt;/sup&amp;gt;N, and Δ&amp;lt;sup&amp;gt;14&amp;lt;/sup&amp;gt;C analysis