ScienceShot: The Flatfish's Wandering Eye  25 June 2012 3:07 pm
Matt Friedman  Halibut, sole, and flounder may be renowned in
culinary circles, but they're also famous among evolutionary
biologists. Unlike most vertebrates, the flatfish is profoundly
asymmetrical, with both eyes on one side of its head. Scientists
think the asymmetry arose as an adaptation to living on the sea
floor, with one side of the body constantly exposed to potential
predators. But how it happened has stumped researchers for
decades. Did a single severe mutation misplace an eye, or did
one eye migrate gradually over time? The answer may lie with
Heteronectes, a 50-million-year-old fossilized flatfish (inset)
whose discovery is reported online today in the Journal of
Vertebrate Paleontology. Heteronectes has one eye on one side of
its head (right), and the other near the top of its skull on the
other side (left). Along with Amphistium, a contemporary of
Heteronectes with a similar intermediately placed eye,
Heteronectes seems to repres