Omomyidae is a group of early primates that radiated during the Eocene epoch between about 55 to 34 million years ago (mya). Fossil omomyids are found in North America, Europe & Asia making it one of two groups of Eocene primates with a geographic distribution spanning holarctic continents, the other being the adapids. Early representatives of the Omomyidae and Adapidae appear suddenly at the beginning of the Eocene in North America, Europe, and Asia, and are the earliest known crown primates.
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.
Uintatherium is an extinct genus of herbivorous mammal that lived during the Eocene epoch. Two species are currently recognized: U. anceps from the United States during the Early to Middle Eocene and U. insperatus of Middle to Late Eocene China.
Plesiadapis is one of the oldest known primate-like mammal genera which existed about 55–58 million years ago in North America and Europe. Plesiadapis means "near-Adapis", which is a reference to the adapiform primate of the Eocene period, Adapis. Plesiadapis tricuspidens, the type specimen, is named after the three cusps present on its upper incisors.
Eosimias is a genus of early primates, first discovered and identified in 1999 from fossils collected in the Shanghuang fissure-fillings of Liyang, the southern city of Jiangsu Province, China. It is a part of the family Eosimiidae, and includes three known species: Eosimias sinensis, Eosimias centennicus, and Eosimias dawsonae. It provides us with a glimpse of a primate skeleton similar to that of the common ancestor of the Haplorhini. The name Eosimias is designed to mean "dawn monkey", from Greek eos "dawn" and Latin simius "monkey".
Megistotherium is an extinct genus of hyaenodontid, the only known species of which is Megistotherium osteothlastes. It is possibly a junior synonym of Hyainailouros sulzeri.
Pronycticebus was a genus of adapiformes primates that lived during the middle to middle late Eocene. It is represented by two species, Pronycticebus gaudryi and Pronycticebus neglectus, of which an almost complete specimen was found in Germany, and the Quercy Phosphorites Formation of France.
Miacis is a genus of extinct carnivorous mammals that appeared in the late Paleocene and continued through the Eocene. The genus Miacis is not monophyletic but a diverse collection of species that belong to the stemgroup within the Carnivoramorpha. As such, most Miacis species belong to the group of early carnivores that represent the ancestors of the modern order, the crown-group Carnivora. However, the species Miacis cognitus is placed not in the stem-group but among the Caniformia, one of the two suborders of the crown-group Carnivora.
Smilodectes is a genus of adapiform primate that lived in North America during the middle Eocene. It possesses a post-orbital bar and grasping thumbs and toes. Smilodectes has a small cranium size and the foramen magnum was located at the back of the skull, on the occipital bone.
Altanius is a genus of extinct primates found in the early Eocene of Mongolia. Though its phylogenetic relationship is questionable, many have placed it as either a primitive omomyid or as a member of the sister group to both adapoids and omomyids. The genus is represented by one species, Altanius orlovi, estimated to weigh about 10–30g from relatively well-known and complete dental and facial characteristics.
A toothcomb is a dental structure found in some mammals, comprising a group of front teeth arranged in a manner that facilitates grooming, similar to a hair comb. The toothcomb occurs in lemuriform primates, treeshrews, colugos, hyraxes, and some African antelopes. The structures evolved independently in different types of mammals through convergent evolution and varies both in dental composition and structure. In most mammals the comb is formed by a group of teeth with fine spaces between them. The toothcombs in most mammals include incisors only, while in lemuriform primates they include incisors and canine teeth that tilt forward at the front of the lower jaw, followed by a canine-shaped first premolar. The toothcombs of colugos and hyraxes take a different form with the individual incisors being serrated, providing multiple tines per tooth.
Dinopithecus is an extinct genus of very large primate closely related to the baboon that lived during the Pliocene to the Pleistocene epoch of South Africa. It was named by Scottish paleontologist Robert Broom in 1937. The only species currently recognized is Dinopithecus ingens, as D. quadratirostris has been reassigned to the genus Soromandrillus. It is known from several infilled cave sites in South Africa, all of early Pleistocene age, including Skurweberg, Swartkrans, and Sterkfontein.
Biretia is an extinct genus of Old World monkey belonging to the extinct family Parapithecidae. Fossils are found from Late Eocene strata in Egypt.
Sinopa is a genus of hyaenodontid that lived in North America and Asia during the early to middle Eocene.
Anaptomorphinae is a pre-historic group of primates known from Eocene fossils in North America and Europe and later periods of Paleocene Asia, and are a sub-family of omomyids. The anaptomorphines is a paraphyletic group consisting of the two tribes Trogolemurini and Anaptomorphini. Anaptomorphine radiation in Wyoming, one of the most detailed records of changes within populations and between species in the fossil record, has provided remarkable evidence of transitional fossils.
Afrotarsius is a primate found in the Paleogene of Africa.
The Wasatch Formation (Tw) is an extensive highly fossiliferous geologic formation stretching across several basins in Idaho, Montana Wyoming, Utah and western Colorado. It preserves fossils dating back to the Early Eocene period. The formation defines the Wasatchian or Lostcabinian, a period of time used within the NALMA classification, but the formation ranges in age from the Clarkforkian to Bridgerian.
The Bridger Formation is a geologic formation in southwestern Wyoming. It preserves fossils dating back to the Ypresian Epoch of the Paleogene Period. The formation was named by American geologist Ferdinand Vandeveer Hayden for Fort Bridger, which had itself been named for mountain man Jim Bridger. The Bridger Wilderness covers much of the Bridger Formation's area.
David Tab Rasmussen, also known as D. Tab Rasmussen, was an American biological anthropologist. Specializing in both paleontology and behavioral ecology with interests in Paleogene mammals, early primate evolution, prosimians, and birds, he synthesized multiple fields of study in order to better understand evolutionary processes. His field research spanned the western United States as well as internationally in Africa and the Neotropics. He published over 85 research articles.
Uintaceras is an extinct genus of medium-sized rhinoceros that lived in North America during the Middle Eocene, with only the type species U. radinskyi, named in 1997, currently contained within the genus. Uintaceras is the oldest and most primitive species of the Rhinocerotidae known to date, although it may have belonged to its own, currently unknown, separate family. The dubious species Forstercooperia (Hyrachyus) grandis is also possibly the same animal as Uintaceras, although the Asian material of F. grandis was assignable to Forstercooperia confluens.
