Fish Fossil Finishes Mystery

By Margaret Lyons in News on Jul 9, 2008 9:48PM

2008_7_9.fish.jpg
Behold the wonk-eyed Amphistium fossils.

U of C grad student Matt Friedman has discovered a new species and reclassified two previously discovered fossils, thus helping clear up a centuries-long confusion about the evolution of flatfish, those bad boys with both peepers on one side of their heads.

The flatfish has always been regarded as an oddity. Although the immature fish has eyes on opposite sides of its head, one of the eyes migrates around its skull before it reaches maturity. Yet there was no evidence for this development process in the fossil record.

Some evolutionary biologists, including Darwin, have argued that the trait evolved gradually over many generations of flatfish. If true, intermediate flatfish with partially offset eyes would once have lived — but no such fossils have ever been identified, giving succour to both creationists and those arguing for sudden jumps in evolution.

Friedman, who studies evolutionary biology, found three "transitional forms," aka fossils with lopsided eyes, which gives credit to the theory that the asymmetrical eyes evolved gradually, rather than through a "hopeful monster" process. [Nature, MSNBC, U of C's release]


Also, this is a terrific opportunity for one of my favorite kid jokes!

Q: What do you call a fish with no eyes?
A: Fsh.