Contemporary crinoids

Today I admit to a glaring gap in my knowledge about fossils! I have always had a particular affinity for crinoids, since I used to find pieces of them in the schoolyard as a child (see Petrified wood). My eye was caught yesterday by this article about them, in which researchers have isolated the oldest biological molecules from complete fossils. "These molecules are not DNA, and they'll never be as good as DNA as a means to define evolutionary relationships, but they could still be useful. We suspect that there's some kind of biological signal there—we just need to figure out how specific it is before we can use it as a means to track different species," said William Ausich, geologist at Ohio State University. The crinoids from which they extracted the biomarkers are 350 million years old, but the caption for the photograph in the article (reproduced above) describes doctoral student Christina O'Malley holding a modern crinoid. Sure enough, these marine creatures never went extinct – there are 540 species of them in existence! The sea is full of "sea lilies"...

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