Pigments of a Fossil Echinoderm

Abstract

SEVERAL years ago, I described¹ the discovery of crystallized organic pigments (‘fringelite’) in a fossil crinoid (Millericrinus) of upper Jurassic age. Additional specimens have now been collected at the two original locations (Fringeli and Liesberg, both in north-western Switzerland). The pigments are isolated by solvent extraction and separated by repetitive chromatography and fractional crystallization. Six pigments (fringelite A–F) have been isolated : additional pigments remaining in the fossil after exhaustive extraction with pyridine can be dissolved in concentrated sulphuric acid in which they exhibit an absorption spectrum similar to that of the more soluble fringelites. All these pigments are similar in respect to their absorption spectra, the colour of their solutions (red in organic solvents, green in sulphuric acid), the formation of green, insoluble sodium salts and the ease with which acetyl- and benzoyl-derivatives are formed. In all these properties the fringelites strongly resemble extended quinones of the type of aphin² or hypericin³. They even give the characteristic aphin-reaction, a blue(-violet) colour, on treatment with acetic anhydride containing a small amount of sulphuric acid.