Preservation of hypericin and related polycyclic quinone pigments in fossil crinoids

The fringelite pigments, a group of phenanthroperylene quinones discovered in purple coloured specimens of the Upper Jurassic crinoid Liliocrinus, demonstrate exceptional preservation of organic compounds in macrofossils. Here we report the finding of hypericin and related phenanthroperylene quinones in Liliocrinus munsterianus from the original ‘Fringeli’ locality and in the Middle Triassic crinoid Carnallicrinus carnalli. Our results show that fringelites in fact consist of hypericin and closely related derivatives and that the stratigraphic range of phenanthroperylene quinones is much wider than previously known. The fossil occurrence of hypericin indicates a polyketide biosynthesis of hypericin-type pigments in Mesozoic crinoids analogous to similar polyketides, which occur in living crinoids. The common presence of a characteristic distribution pattern of the fossil pigments and related polycyclic aromatic hydrocarbons further suggests that this assemblage is the result of a stepwise degradation of hypericin via a general diagenetic pathway

Origins of radial symmetry identified in an echinoderm during adult development and the inferred axes of ancestral bilateral symmetry

How the radial body plan of echinoderms is related to the bilateral body plan of their deuterostome relatives, the hemichordates and the chordates, has been a long-standing problem. Now, using direct development in a sea urchin, I show that the first radially arranged structures, the five primary podia, form from a dorsal and a ventral hydrocoele at the oral end of the archenteron. There is a bilateral plane of symmetry through the podia, the mouth, the archenteron and the blastopore. This adult bilateral plane is thus homologous with the bilateral plane of bilateral metazoans and a relationship between the radial and bilateral body plans is identified. I conclude that echinoderms retain and use the bilateral patterning genes of the common deuterostome ancestor. Homologies with the early echinoderms of the Cambrian era and between the dorsal hydrocoele, the chordate notochord and the proboscis coelom of hemichordates become evident