''Eobothus'' ('Dawn

flounder Flounders are a group of flatfish species. They are demersal fish, found at the bottom of oceans around the world; some species will also enter estuaries. Taxonomy The name "flounder" is used for several only distantly related species, thou ...

') is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

flatfish A flatfish is a member of the Ray-finned fish, ray-finned demersal fish order (biology), order Pleuronectiformes, also called the Heterosomata, sometimes classified as a suborder of Perciformes. In many species, both eyes lie on one side of the ...

from the

Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...

epoch 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 long, surrounded by elongated dorsal and

anal fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as se ...

s. 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 chaneti'' is a fossil fish which has been identified as a primitive flatfish, dating to the early Eocene (Lutetian stage) of France. ''Heteronectes'' is reported to be a transitional fossil. In a typical modern flatfish, the head ...

'', in which the eyes only partially migrated.

References

Eocene fish of Asia Eocene fish of Europe Pleuronectiformes Prehistoric ray-finned fish genera {{Pleuronectiformes-stub