Gars are an ancient group of ray-finned fish in the family Lepisosteidae. They comprise seven living species of fish in two genera that inhabit fresh, brackish, and occasionally marine waters of eastern North America, Central America and Cuba in the Caribbean, though extinct members of the family were more widespread. They are the only surviving members of the Ginglymodi, a clade of fish which first appeared during the Triassic period, over 240 million years ago, and are one of only two surviving groups of holosteian fish, alongside the bowfins, which have a similar distribution.
Lepisosteus is a genus of gars in the family Lepisosteidae. It contains four extant species, found throughout eastern and central North America. It is one of two extant gar genera alongside Atractosteus.
The Green River Formation is an Eocene geologic formation that records the sedimentation in a group of intermountain lakes in three basins along the present-day Green River in Colorado, Wyoming, and Utah. The sediments are deposited in very fine layers, a dark layer during the growing season and a light-hue inorganic layer in the dry season. Each pair of layers is called a varve and represents one year. The sediments of the Green River Formation present a continuous record of six million years. The mean thickness of a varve here is 0.18 mm, with a minimum thickness of 0.014 mm and maximum of 9.8 mm.
Knightia is an extinct genus of clupeid bony fish that lived in the freshwater lakes and rivers of North America and Asia during the Eocene epoch. The genus was erected by David Starr Jordan in 1907, in honor of the late University of Wyoming professor Wilbur Clinton Knight, "an indefatigable student of the paleontology of the Rocky Mountains." It is the official state fossil of Wyoming, and the most commonly excavated fossil fish in the world.
Fossil Butte National Monument is a United States National Monument managed by the National Park Service, located 15 miles (24 km) west of Kemmerer, Wyoming, United States. It centers on an assemblage of Eocene Epoch animal and plant fossils associated with Fossil Lake—the smallest lake of the three great lakes which were then present in what are now Wyoming, Utah, and Colorado. The other two lakes were Lake Gosiute and Lake Uinta. Fossil Butte National Monument was established as a national monument on October 23, 1972.
Heliobatis is an extinct genus of stingray in the Myliobatiformes family Dasyatidae. At present the genus contains the single species Heliobatis radians.
Diplomystus is an extinct genus of freshwater and marine clupeomorph fish distantly related to modern-day extant herrings, anchovies, and sardines. It is known from the United States, China, and Lebanon from the Late Cretaceous to the middle Eocene. Many other clupeomorph species from around the world were also formerly placed in the genus, due to it being a former wastebasket taxon. It was among the last surviving members of the formerly-diverse order Ellimmichthyiformes, with only its close relative Guiclupea living for longer.
Asineops is an enigmatic genus of extinct freshwater ray-finned fish from the Eocene. It is the only member of the family Asineopidae and contains a single species, A. squamifrons, from the famous Green River Formation of Colorado, Wyoming, and Utah. It was described by Edward Drinker Cope in 1870. The name comes from the Greek for "donkey-faced".
Atractosteus is a genus of gars in the family Lepisosteidae, with three extant species. It is one of two surviving gar genera alongside Lepisosteus.
Asterotrygon is an extinct genus of stingray from the Eocene Green River Formation in Wyoming. Several complete skeletons representing juveniles, adults, males and females have been uncovered from the late early Eocene Fossil Butte Member of the formation. The type and only species, A. maloneyi, was named in 2004 on the basis of these fossils. Another stingray, Heliobatis, is also known from the formation. Asterotrygon is a primitive stingray closely related to the living family Urolophidae whose ancestors likely originated in the Indo-Pacific. It lived in Fossil Lake, a body of water that existed in a subtropical mountainous region for only about 2 million years.
Bahndwivici is an extinct genus of lizard known from a nearly complete and articulated skeleton discovered in rocks of the Green River Formation of Wyoming, United States. The skeleton is very similar to that of the modern Chinese crocodile lizard, Shinisaurus.
Afairiguana avius is an extinct iguanid lizard known from a nearly complete and articulated skeleton discovered in rocks of the Early Eocene-aged Green River Formation of Wyoming, United States. As of the initial description, the skeleton represents the oldest complete iguanian from the Western Hemisphere, and is the oldest representative of the extant iguanid family of anoles, Polychrotidae.
Roger Lansing Grande, more commonly known as Lance Grande, is an evolutionary biologist and curatorial scientist. His research and work is focused on Paleontology, Ichthyology, Systematics and Evolution. He is well known for his work on the paleontology of the Green River Formation and for his detailed monographs on the comparative anatomy and evolution of ray-finned fishes. He has also published books on broader issues, engaging larger audiences on the importance of the natural and the social sciences.
Morsoravis is an extinct genus of neoavian bird from the Early Eocene Fur Formation of Denmark. It contains a single named species, Morsoravis sedilis. Fossils of Morsoravis have also been found in the Green River Formation of Wyoming and possibly the Nanjemoy Formation of Virginia.
Atractosteus grandei is an extinct species of gar in the family Lepisosteidae. Remains have been found in Lower Paleogene sediments from North Dakota. A. grandei belonged to the genus Atractosteus which includes modern day species of gars such as the giant alligator gar and the tropical gar. It is named after paleontologist and ichthyologist Lance Grande.
Cuneatus is an extinct genus of gar that inhabited western North America during the early Paleogene. As the genus name suggests, they are distinguishable from modern gar by their cuneate (wedge-shaped) heads, with a significantly shortened snout. Three species are known: C. cuneatus, C. maximus, and C. wileyi.
Masillosteus is an extinct genus of gar that inhabited western North America and Europe during the Eocene. It is known from two species, each from a famous freshwater lagerstätte: M. kelleri from the Messel pit in the Messel Formation of Germany, and M. janeae from Fossil Butte in the Green River Formation of Wyoming. They are known from only a few specimens from both localities, and may have not been permanent inhabitants of the fossil lakes where they were preserved.
Erismatopterus is an extinct genus of percopsiform fish which lived during the early to middle Eocene epoch and containing the single species Erismatopterus levatus. A report of the genus in sediments of similar age in Washington State have been discredited. Erismatopterus is treated as part of the family Percopsidae, but formerly was the type genus of the extinct family Erismatopteridae. The genus is closely related to Amphiplaga of related lake sediments. Shoaling behavior has been reported from a mass mortality fossil of E. levatus and attributed as a predator-evasion response behavior.
Cyclurus is an extinct genus of freshwater amiid ray-finned fish known from the Late Cretaceous to the Early Oligocene across much of the Northern Hemisphere. It is thought to be the closest relative of the extant bowfins in the genus Amia, although species of Cyclurus were significantly smaller in size compared to Amia.
Atractosteus atrox, the Green River atrox gar, is an extinct species of gar from the Early Eocene of western North America. It is known from many well-preserved specimens found in the famous Fossil Butte deposits of the Green River Formation in Wyoming, US, in addition to a possible vertebra from the Bridger Formation.
