''Amia''? ''hesperia'' 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
bowfin
The bowfin (''Amia calva'') is a bony fish, native to North America. Common names include mudfish, mud pike, dogfish, grindle, grinnel, swamp trout, and choupique. It is regarded as a relict, being the sole surviving species of the Halecomorphi ...
family,
Amiidae. 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 southeastern
British Columbia
British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...
. The species is one of eight fish species identified in the
Eocene Okanagan Highlands paleofauna.
The species has been suggested to possibly belong to either ''Amia'' or the extinct genus ''
Cyclurus''.
Distribution and paleoenvironment
''Amia''? ''hesperia'' fossils have been recovered from two locations in the
Eocene Okanagan Highlands, the
Allenby Formation of the Princeton, British Columbia region
and as isolated scales from 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. 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 of Eastern North America and Eastern Asia. Based on the fossil
biotas the lakes were higher and cooler than the