Hiodontiformes

A 48.5 million years old fossil of Hiodon woodruffi from the Klondike Mountain Formation in Washington (USA).

• North America
• China

The Hiodontiformes are one of the genuine bony fish ( Teleostei ) the east only by two species from the rivers and lakes of North America's Rocky Mountains is represented today in the Cretaceous and the Tertiary, however, had a wider distribution over the northern hemisphere, and in western North America, and occurred in East Asia.

Features

The recent Hiodontiformes are herring -like fish that are about half a meter long. All Hiodontiformes show the following diagnostic synapomorphies:

The hyomandibular is two-headed. A special skin bones ( " dermosphenotic bone" ), which lies on top of the head behind the eye sockets, is Y -shaped. The operculum ( gill cover bone ) has the shape of an irregular parallelogram. The upper arm of the Posttemporale is more than twice as long as the bottom. The pelvic fins are templated by seven fin rays.

Genera

• † Plesiolycoptera (early Cretaceous, northeastern China)
• † Yanbiania ( Lower Cretaceous, northeastern China)
• Family Hiodontidae Hiodon (late Eocene to the present day, north-western, central and eastern North America) Gold eye ( Hiodon alosoides )
• Moon eye ( Hiodon tergisus )