Heteronectes chaneti

Heteronectes is a fossil fish which has been identified as a primitive flatfish, dating to the early Eocene (Lutetian stage) of France. The genus contains a single species H. chaneti.

Heteronectes is reported to be a transitional fossil. In a typical modern flatfish, the head is asymmetric with both eyes on one side of the head. In Heteronectes, the transition from the typical symmetric head of a vertebrate is incomplete, with one eye positioned near the top of the head, very similar (but less so) to its Italian relative Amphistium. The rest of the skeleton also has some primitive features in common with other Percomorph groups, but absent in living flatfishes.