Hiodon rosei

Hiodon rosei Hussakof 1916

Eocene

Lutetian

Kamloop

Tranquille shale

Cache Creek

British Columbia

Canada

Today, the family Hiodontiadae is represented by two species and a single genus (Hiodon) restricted to North America. They are large-eyed, fork-tailed fish that physically resemble shads.

The "goldeye", Hiodon alosoides, is widespread across Nord America. It prefers turbid slower-moving waters of lakes and rivers.

The mooneye, Hiodon tergisus, is also widespread across North America, living in the clear waters of lakes, ponds, and rivers.

Hiodontids feed mainly on insects, insect larvae, and a few small fish.

The fossil genus Eohiodon was set up by Cavender in 1966 based on a review of Leuciscus rosei by Hussakof. Since then, three additional species have been included in this genus: Eohiodon rosei is the type species and known from the Tranquille beds near Kamloops, the Horsefly beds near Horsefly, British Columbia, Canada and the Allenby Formation near Princeton.

Eohiodon woodruffi Wilson 1978 is known from the Klondike Mountain Formation near Republic, Washington and the Horsefly beds near Horsefly, British Columbia.

Eohiodon falcatus Grande 1978 has been found from the Fossil Butte Member of the Green River Formation, Lincoln County, Wyoming, USA.

Recent study by Li, Wilson, and Grande, 1997 of new specimen of both Eohiodon falcatus and Eohiodon woodruffi indicates that the two specimen are indistinguishable in the vast majority of characters; Eohiodon falcatus should be treated as a junior synonym of Eohiodon woodruffi.

In their 2008 paper Grande & Hilton reassessed the Hiodontidae and concluded: " After correcting the descriptions of the fossil taxa, we could find no valid synapomorphies to separate the genus †Eohiodon from the genus Hiodon. Therefore, we conclude that †Eohiodon should be regarded as a synonym of Hiodon."

Grande, L. 1979. Eohiodon falcatus, a new species of hiodontid (Pisces) from the late early Eocene Green River Formation of Wyoming. Journal of Paleontology, 53:103-111.

Wilson, M. V. H. 1978. Eohiodon woodruffi n. sp. (Teleostei, Hiodontidae) from the middle Eocene Klondike Mountain Formation near Republic, Washington. Canadian Journal of Earth Sciences, 15:679-686.

Cavender, T. 1966. Systematic position of the North American Eocene fish, "Leuciscus" rosei Hussakof. Copeia, 1966:311-320.