Mesonychia is an extinct taxon of small- to large-sized carnivorous ungulates related to artiodactyls. Mesonychians first appeared in the early Paleocene, went into a sharp decline at the end of the Eocene, and died out entirely when the last genus, Mongolestes, became extinct in the early Oligocene. In Asia, the record of their history suggests they grew gradually larger and more predatory over time, then shifted to scavenging and bone-crushing lifestyles before the group became extinct.
Anthracotherium is an extinct genus of artiodactyls characterized by having 44 teeth, with five semi-crescentic cusps on the crowns of the upper molars. The genus ranged from the middle Eocene period until the early Miocene, having a distribution throughout Eurasia. Material subjectively assigned to Anthracotherium from Pakistan suggests the last species died out soon after the start of the Miocene.
Dinictis is a genus of the Nimravidae, an extinct family of feliform mammalian carnivores, also known as "false saber-toothed cats". Assigned to the subfamily Nimravinae, Dinictis was endemic to North America from the Late Eocene to Early Miocene epochs, existing for about 16.8 million years.
Archaeotherium is an extinct genus of entelodont artiodactyl endemic to North America during the Eocene and Oligocene epochs. Archaeotherium fossils are most common in the White River Formation of the Great Plains, but they have also been found in the John Day Basin of Oregon and the Trans-Pecos area of Texas. Archaeotherium's fossils come from North America, between the Priabonian and Rupelian stages of the Eocene and Oligocene. Up to fifteen species of Archaeotherium have been identified, which are divided into three subgenera. One contains the type species, A. mortoni, among others; another contains very large taxa formerly named Megachoerus and Pelonax; and the last contains A. calkinsi.
Pristichampsus is a non-diagnostic and potentially dubious extinct genus of crocodylian from France and possibly also Kazakhstan that is part of the monotypic Pristichampsidae family. As the type species, Pristichampsus rollinatii, was based on insufficient material when described in 1831 and 1853, the taxonomic status of the genus is in doubt, and other species have been referred to other genera, primarily Boverisuchus.
Merycoidodon is an extinct genus of herbivorous artiodactyl of the family Merycoidodontidae, more popularly known by the name Oreodon. It was endemic to North America during the Middle Eocene to Middle Miocene existing for approximately 30 million years.
Elomeryx is an extinct genus of artiodactyl ungulate, and is among the earliest known anthracotheres. The genus was extremely widespread, first being found in Asia in the middle Eocene, in Europe during the latest Eocene, and having spread to North America by the early Oligocene. The closest living relatives of the Elomeryx are bovids, suids, and cetaceans.
Daphoenus is an extinct genus of amphicyonids. Daphoenus inhabited North America from the Late Eocene to the Middle Miocene, 37.2—16.0 Mya, existing for approximately 21 million years.
Anthracotheriidae is a paraphyletic family of extinct, hippopotamus-like artiodactyl ungulates related to hippopotamuses and whales. The oldest genus, Elomeryx, first appeared during the middle Eocene in Asia. They thrived in Africa and Eurasia, with a few species ultimately entering North America during the Oligocene. They died out in Europe and Africa during the Miocene, possibly due to a combination of climatic changes and competition with other artiodactyls, including pigs and true hippopotamuses. The youngest genus, Merycopotamus, died out in Asia during the late Pliocene, possibly for the same reasons. The family is named after the first genus discovered, Anthracotherium, which means "coal beast", as the first fossils of it were found in Paleogene-aged coal beds in France. Fossil remains of the anthracothere genus were discovered by the Harvard University and Geological Survey of Pakistan joint research project (Y-GSP) in the well-dated middle and late Miocene deposits of the Pothohar Plateau in northern Pakistan.
Anthracokeryx is a genus of extinct artiodactyl ungulate mammal belonging to Anthracotheriidae that lived in Asia during the middle to late Eocene.
Leidyosuchus is an extinct genus of alligatoroid from the Late Cretaceous of Alberta. It was named in 1907 by Lawrence Lambe, and the type species is L. canadensis. It is known from a number of specimens from the middle Campanian age Dinosaur Park Formation. It was a medium-sized alligatoroid, with a maximum skull length greater than 40 centimeters (16 in).
Herpetotherium is an extinct genus of metatherian mammal, belonging to the possibly paraphyletic family Herpetotheriidae. Native to North America from the Eocene to Early Miocene, fossils have been found in California, Oregon, Texas, Florida, Montana, Wyoming, Colorado, North and South Dakota, Nebraska, and Saskatchewan. The oldest species, H. knighti, is dated to around 50.3 mya, and the most recent, an unnamed species, may be as recent as 15.97 mya. A morphological analysis of marsupials and basal metatherians conducted in 2007 found Herpetotherium to be the sister group to extant marsupials. It is the youngest known metatherian from North America until the migration of the Virginia opossum from South America within the last 2 million years.
Artiocetus is an extinct genus of early whales belonging to the family Protocetidae. It was a close relative to Rodhocetus and its tarsals indicate it resembled an artiodactyl.
Cylindracanthus is an extinct, enigmatic genus of marine ray-finned fish with fossils known throughout North America, Europe, Asia and Africa from the Late Cretaceous to the late Eocene, with potential Oligocene records and a possible Miocene record also known. It is exclusively known from its distinctive partial remains, which are long cylindrical bony spines that are usually considered rostrum fragments, as well as some associated teeth. These spines are abundant & widespread throughout this timespan, and are useful indicators of a nearshore marine environment, but the taxonomic identity of the fish is still highly uncertain and debated.
Boavus is an extinct genus of boa known primarily from Eocene-aged strata of North America. At least three species are known from the Middle Eocene Green River lagerstätte in Wyoming, two species from Eocene strata of Uinta County, and at least one species is known from the middle to late Eocene-aged Sespe Formation of California. Boavus was a small snake measuring between 1 and 2 metres long.
Sinopa is an extinct genus of placental mammals from extinct family Sinopidae within extinct order Hyaenodonta, that lived in North America and Asia from the early to middle Eocene.
Agriochoerus is an extinct genus of scansorial herbivore of the tylopod family Agriochoeridae, endemic to North America. Agriochoerus and other agriochoerids possessed claws, which is rare within Artiodactyla, as well as likely being scansorial. Agriochoerus was first described in 1869.
Microbunodon was a genus of extinct artiodactyl mammals in the family Anthracotheriidae. It lived between the upper Eocene and the lower Pliocene. Its fossil remains have been found in Europe and Asia.
Helohyidae were a group of artiodactyl mammals. They were most prominent in the mid-to-upper Eocene.
The anthracotheriines are an extinct subfamily of anthracotheres that comprised Paleogene to early Neogene North American and Eurasian artiodactyls. The group contained the genera Anthracotherium, Heptacodon, and Paenanthracotherium, as well as possibly Myaingtherium and Siamotherium. They were small to large sized anthracotheres, and when compared to the other two subfamilies, Microbunodontinae and Bothriodontinae, anthracotheriines are found to occupy a primitive, basal position in the family.
