Eobothus is an extinct genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 of flatfish

Flatfish

The flatfish are an order of ray-finned fish, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the head, one or the other migrating through and around the head during development...

 from the Eocene

Eocene

The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...

 period of China, India and Europe.

Eobothus is significant as one of the earliest genera of flatfish, one of the last major fish groups to evolve. It closely resembled modern flatfish, with an oval-shaped body about 10 centimetres (3.9 in) long, surrounded by elongated dorsal

Dorsal fin

A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

 and anal fins. In the adult, the eyes were both located on the left side of the head, as in modern species, and the fish would have lain flat against the seafloor on its right side. This was an evolutionary advance from still earlier flatfish, such as Heteronectes

Heteronectes

Heteronectes is a fossil fish which has been identified as an early relative of the Flatfish, and as a Transitional fossil. In a typical modern flatfish, the head is asymmetric with both eyes on one side of the head...

, in which the eyes only partially migrated.