Fossil fish are the most common fossil finds from the Fossil Butte Member (FBM). So far, 27 species of fish have been discovered in the FBM. The diversity of species and the abundance of fossils, together allow scientists to understand the ecosystem of Fossil Lake.
Stingrays - 2 Species Identified: Heliobatis radians & Asterotrygon maloneyi
There are almost 200 modern stingray species.
Paddlefish - Crossopholis magnicaudatusOrder Acipenseriformes, Family Polydontidae
C. magnicaudatus is often preserved with fish in the stomach, indicating this species was a predator. This fossil species is most commonly found in shallow-water deposits, but very few juveniles have been discovered. This could possibly indicate that C. magnicaudatus matured and spawned in connecting rivers before migrating to Fossil Lake as an adult.
This species' name comes from the thousands of tiny, fringed scales covering its body, crossopholis meaning 'fringed scale.'
The maximum known size of this fossil species is 4 feet.
Gars - 4 Species Identified: Lepisosteus bemisi & Atractosteus simplex & Atractosteus atrox & Masillosteus janeiOrder Lepisosteiformes, Family Lepisosteidae
Seven living gar species are found in freshwaters of North America, Central America, and Cuba. Of the 4 Fossil Lake gar species, all but one are very similar to modern gars.
M. janei lacked the long jaw and sharp teeth characteristic of modern gars. M janei. teeth were instead rounded and flat, ideal for crushing small invertebrates like snails and crayfish. This gar species is primarily found in association with these fossil invertebrates.
Outside of the FBM, gar scales are much more common fossils than complete skeletons. The gars' characteristic, diamond-shaped scales have historically been used by humans as arrowheads and on protective breastplates. There tough scales offer significant protection from would be predators.
Modern gar species often migrate up rivers to spawn. This is one explanation for the lack of juvenile gar fossils found in the FBM.
Bowfins - 2 Species Identified: Cyclurus gurleyi & Amia pattersoniOrder Amiiformes, Family Amiidae
The genus Cyclurus is not known to have survived past the Eocene Epoch, possibly dying out about 35 million years ago. The closely related Amia genus survives today with the North American A. calva species.
The long jaw and pointed teeth found on A. pattersoni specimens are indicators of a possible apex predator.
The crushing jaws found on C. gurleyi specimens suggest an invertebrate diet.
Ray-finned Fish - Diplomystus dentatusOrder Ellimmichthyiformes, Family Paraclupeidae
The last known species of the Ellimmichthyiformes order went extinct sometime in the middle Eocene. D. dentatus is a primitive relative of the modern day herring. The genus Diplomystus is also known from fossil deposits in China.
D. dentatus is the 2nd most common fossil fish found from Fossil Lake. Specimens ranging from embryonic size (about 0.7 inches) to full-grown adults (about 26 inches) are common. Smaller-sized specimens are more commonly found in mid-lake than near-shore deposits. This suggests that D. dentatus spawned in open water.
This species' upturned mouth indicates it fed at the surface of Fossil Lake. D. dentatus specimens are commonly found with other fish stuck in their mouths, including other D. dentatus specimens.
Herrings - 2 Species Identified: Knightia eocaena & Knightia altaOrder Clupeiformes, Family Clupeidae
The Clupeidae family has an estimated 50 modern freshwater species. Clupeidae species can lay as many as 200,000 eggs at once, allowing species to multiply quickly. Modern species are also prone to mass die offs.
K. eocaena is:
K. eocaena specimens of all sizes are found in mass mortality plates, indicating this species schooled as both a juvenile and adult. The average adult size of K. eocaena specimens is about 6 inches, though specimens as large as 10 inches have been found.
Beaked Sandfish - Notogoneus osculusOrder Gonorynchiformes, Family Gonorynchidae
N. osculus was the last survivor of the Gonorynchiformes order in North America. There are 5 modern species in the Gonorynchidae family. They inhabit tropical marine regions of the Indo-Pacific Oceans.
Very young juveniles and large adults are the only N. osculus specimens found from Fossil Lake. This could indicate that N. osculus was a migratory species. Their lifecycle may have consisted of:
Perches - 7 Species Identified: Mioplosus labracoides & Cockerellites liops & Priscacara serrata & 2 undescribed Priscacara species & Hypsiprisca hypsacantha & 1 undescribed Hypsiprisca species
Mystery Fish - Asineops squamifronsOrder Unknown, Family Asineopidae
Bony-Tongue Fish - 2 Species Identified: Phareodus encaustus & Phareodus testisOrder Osteoglossiformes, Family Osteoglossidae
Living members of the Osteoglossidae family:
Trout-Perch - Amphiplaga brachypteraOrder Percopsiformes, Family Percopsidae
The Percopsidae family has one modern genus with 2 species. They are restricted to freshwater rivers and lakes of North America.
A. brachyptera is the earliest known member of the Percopsidae family, and is known exclusively from Fossil Lake deposits.
Larval-size A. brachyptera specimens are almost completely absent from the FBM. This suggests that A. brachyptera spawned in rivers.
A. brachyptera is also never found in mass mortality plates, indicating this species was solitary and not a schooling fish.
Mooneye - Hiodon falcatusOrder Hiodontiformes, Family Hiodontidae
Living members of the Hiodon genus:
Last updated: November 17, 2022