''Hiodon woodruffi'' is an
extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of
bony fish
Osteichthyes (), popularly referred to as the bony fish, is a diverse superclass of fish that have skeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes, which have skeletons primarily composed of cartilag ...
in the
mooneye
Hiodontidae, commonly called mooneyes, is a family of ray-finned fish with a single included genus ''Hiodon''. The genus comprise two living species native to North America and three to five extinct species recorded from Paleocene to Eocene age ...
family,
Hiodontidae
Hiodontidae, commonly called mooneyes, is a family of ray-finned fish with a single included genus ''Hiodon''. The genus comprise two living species native to North America and three to five extinct species recorded from Paleocene to Eocene age ...
. The species is known from
fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
s found in the early
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' ...
deposits of northern
Washington state
Washington (), officially the State of Washington, is a state in the Pacific Northwest region of the Western United States. Named for George Washington—the first U.S. president—the state was formed from the western part of the Washington ...
in the United States and late Eocene deposits in northwestern Montana. The species was first described as ''Eohiodon woodruffi''. ''H. woodruffi'' is one of two Eocene
Okanagan Highlands
The Okanagan Highland is an elevated hilly plateau area in British Columbia, Canada, and the U.S. state of Washington (where it is spelled Okanogan Highlands). Rounded mountains with elevations up to above sea level and deep, narrow valleys are ...
mooneye species, and one of five fish identified in the Klondike Mountain Formation.
Distribution and paleoenvironment
''Hiodon woodruffi'' fossils have been recovered from two locations in the Okanagan highlands, the
Horsefly shale near
Horsefly, British Columbia
Horsefly is an unincorporated community on the northwest shore of the Horsefly River, in the Cariboo region of central British Columbia. The location, via BC Highway 97, Likely Rd, and Horsefly Rd, is about northeast of Williams Lake, and by ro ...
and the several exposures of the
Klondike Mountain Formation
The Klondike Mountain Formation is an Early Eocene (Ypresian) geological formation located in the northeast central area of Washington state. The formation, named for the type location designated in 1962, Klondike Mountain north of Republic, Wash ...
in northern
Ferry County, Washington
Ferry County is a county located on the northern border of the U.S. state of Washington. As of the 2020 census, the population was 7,178, making it the fourth-least populous county in Washington. The county seat and largest city is Republic. Th ...
. Both sites represent upland lake systems that were surrounded by a warm temperate ecosystem with nearby volcanism.
The highlands likely had a
mesic upper microthermal to
lower mesothermal climate, in which winter temperatures rarely dropped low enough for snow, and which were seasonably equitable.
The Okanagan highlands paleoforest surrounding the lakes have been described as precursors to the modern
temperate broadleaf and mixed forests
Temperate broadleaf and mixed forest is a temperate climate terrestrial habitat type defined by the World Wide Fund for Nature, with broadleaf tree ecoregions, and with conifer and broadleaf tree mixed coniferous forest ecoregions.
These fo ...
of Eastern North America and Eastern Asia. Based on the fossil
biotas the lakes were higher and cooler then the