Ancient sea-star lenses found

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Tiny lenses that could have allowed sea stars and brittle stars to respond to light may have evolved at least 57 million years earlier than previously thought.

Some sea and brittle stars living today have an array of lenses on their skeletons that are thought to be sensitive to light. Przemysław Gorzelak at the Polish Academy of Sciences in Warsaw, Mariusz Salamon at the University of Silesia in Sosnowiec, Poland, and their colleagues used microscopy and imaging techniques to identify and describe microlenses in fossilized brittle stars (members of the Ophiuroidea) and sea stars (Asteroidea) dating to 136 million years ago. The lenses resemble those found in modern species. Until now, the earliest examples of fossil stars with such lenses were about 79 million years old.

The microlenses evolved long after the brittle- and sea-star lineages diverged, so may have emerged independently in the two groups from shared structures, the authors suggest.

Evol. Biol. http://doi.org/b2tf (2017)

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