Eocene extinctions

Brontotheriidae (or Titanotheriidae), is a family of extinct mammals belonging to the order Perissodactyla, the order that includes horses, rhinoceroses, and tapirs from the Eocene epoch. Brontotheres had a Holarctic distribution, with the exception of Western Europe: their fossils have been found in North America and Asia, with a few also known from Eastern Europe. In larger and often better-known genera of the group, a paired or battering-ram-like horn was present on the snout above the eye socket, made of bone, unlike the horns of rhinoceroses. However, this feature is not present in all me

Plesiadapiformes ("Adapid-like" or "near Adapiformes") is an extinct basal pan-primates group, as sister to the rest of the pan-primates. The pan-primates together with the Dermoptera form the Primatomorpha. Purgatorius may not be a primate as an extinct sister to the rest of the Dermoptera or a separate, more basal stem pan-primate branch. Even with Purgatorius removed, the crown primates may even have emerged in this group. left|thumb|The plesiadapiform Plesiadapis|Plesiadapis cookei (right), compared to [[Notharctus tenebrosus (left), an early crown primate. Both come from Eocene Wyoming, t

Pteridosperms, also known as seed ferns, are a polyphyletic grouping of extinct seed-producing plants. The earliest fossil evidence for plants of this type are the lyginopterids of late Devonian age. They flourished particularly during the Carboniferous and Permian periods. Pteridosperms declined during the Mesozoic Era and had mostly disappeared by the end of the Cretaceous Period, though Komlopteris seem to have survived into Eocene times, based on fossil finds in Tasmania.

Pakicetidae ("Pakistani whales") is an extinct family of early whales that lived during the Early Eocene in northern South Asia. Unlike modern cetaceans, they had well-developed limbs and were capable of walking. The species included were fox to wolf-sized.

Dinocerata, from Ancient Greek (), "terrible", and (), "horn", or Uintatheria, is an extinct order of large herbivorous hoofed mammals with horns and protuberant canine teeth, known from the Paleocene and Eocene of Asia and North America. With body masses ranging up to they represent some of the earliest known large mammals.

Hyaenodontidae ("hyena teeth") is a family of placental mammals in the extinct superfamily Hyaenodontoidea. Hyaenodontids arose during the early Eocene and persisted well into the early Miocene. Fossils of this group have been found in Asia, North America and Europe.

Ambulocetidae is a family of early cetaceans from northern South Asia. The genus Ambulocetus, after which the family is named, is by far the most complete and well-known ambulocetid genus due to the excavation of an 80% complete specimen of Ambulocetus natans. The other two genera in the family, Gandakasia and Himalayacetus, are known only from teeth and mandibular fragments. Retaining large hindlimbs, it was once thought that they could walk on land—indeed, their name means "walking whales"—, but recent research suggests they may have been fully aquatic like modern cetaceans, though the resea

Remingtonocetidae is a diverse family of early aquatic mammals of the order Cetacea. The family is named after paleocetologist Remington Kellogg.

Protocetidae, the protocetids, form a paraphyletic, diverse and heterogeneous group of extinct cetaceans known from Asia, Europe, Africa, South America, and North America.

Xenungulata ("strange ungulates") is an order of extinct and primitive South American hoofed mammals that lived from the Late Paleocene to Early Eocene (Itaboraian to Casamayoran in the SALMA classification). Fossils of the order are known from deposits in Brazil, Argentina, Peru, and Colombia. The best known member of this enigmatic order is the genus Carodnia, a tapir-like and -sized animal with a gait similar to living African elephants.

Arctocyonidae (from Ancient Greek ἄρκτος (árktos), meaning "bear", and κύων (kúon), meaning "dog", and thus, "bear-dog") is an extinct, possibly polyphyletic family of placental mammals which lived from the late Cretaceous to the early Eocene. They were initially regarded as creodonts, though have since been reassigned to an order of their own, the Arctocyonia. Some have suggested that arctocyonids are ancestral to modern-day artiodactyls, or that they form a sister group. However, more recent phylogenetic analyses suggest that arctocyonids may represent an artificial grouping of extinct ungul

Adapidae is a family of extinct primates that primarily radiated during the Eocene epoch between about 55 and 34 million years ago.

mass extinction

Tillodontia is an extinct suborder of eutherian mammals known from the Early Paleocene to Late Eocene of China, the Late Paleocene to Middle Eocene of North America where they display their maximum species diversity, the Middle Eocene of Pakistan, and the Early Eocene of Europe. Leaving no descendants, they are most closely related to the pantodonts, another extinct group. The tillodonts were medium- to large-sized animals that probably fed on roots and tubers in temperate to subtropical habitats.

Raoellidae () is a family of extinct semiaquatic artiodactyls from the middle Eocene (early Lutetian) closely related to cetaceans. They are known primarily from northern India and Pakistan, especially in the Subathu Group of India, although potential remains of the raoellid Khirtharia have been found in northern China. They are relatively small animals; on average, raoellids were the size of a red fox. However, Khirtharia major, at about twice the size of an average-sized raoellid, would have been approximately the size of a coyote. Meanwhile, the smallest raoellid, Metkatius, was roughly the

Dyrosauridae is a family of extinct neosuchian crocodyliforms that lived from the Campanian to the Eocene. Dyrosaurid fossils are globally distributed, having been found in Africa, Asia, Europe, North America and South America. Over a dozen species are currently known, varying greatly in overall size and cranial shape. A majority were aquatic, some terrestrial and others fully marine (see locomotion below), with species inhabiting both freshwater and marine environments. Ocean-dwelling dyrosaurids were among the few marine reptiles to survive the Cretaceous–Paleogene extinction event.

Viverravidae ("ancestors of viverrids") is an extinct monophyletic family of mammals from extinct superfamily Viverravoidea within the clade Carnivoramorpha, that lived from the early Palaeocene to the late Eocene in North America, Europe and Asia. They were once thought to be the earliest carnivorans and ancestral to extant ones, but now are placed outside the order Carnivora based on cranial morphology as relatives (a plesion-group) to extant carnivorans.

Epihippus is an extinct genus of the modern horse family Equidae that lived in the Eocene, from 46 to 38 million years ago.

thumb|Pezosiren portelli cast skeleton Prorastomidae is a family of extinct sirenians from Jamaica, related to the extant manatees and dugong. The family includes the oldest known fossils of Sirenians, represented in two genera: Pezosiren Pezosiren comprises one known species, Pezosiren portelli, that was discovered in modern-day Jamaica. One of the earliest true Sirenian species, P. portelli is distinct from extant Sirenians due to its quadrupedal stature. The species is estimated to have lived 50 million years ago during the Mid Eocene, and the skeletal elements suggest that P. portelli was

Phenacodontidae is an extinct family of large herbivorous mammals traditionally placed in the "wastebasket taxon" Condylarthra, which may instead represent early-stage perissodactyls. They lived from the late early Paleocene to early middle Eocene (about 60–50 million years ago) and their fossil remains have been found in North America and Europe. The only unequivocal Asian phenacodontid is Lophocion asiaticus.

Hapalodectidae (literal translation 'soft biters': ('soft, tender'), ('biter')) is an extinct family of relatively small-bodied () mesonychian placental mammals from the Paleocene and Eocene of North America and Asia. Hapalodectids differ from the larger and better-known mesonychids by having teeth specialized for cutting (presumably meat), while the teeth of other mesonychids, such as Mesonyx or Sinonyx, are more specialized for crushing bones. Hapalodectids were once considered a subfamily of the Mesonychidae, but the discovery of a skull of Hapalodectes hetangensis showed additional differe

Cimolodonta is a clade of multituberculate mammals that lived from the Cretaceous to the Eocene. They probably lived something of a rodent-like existence until their ecological niche was assumed by true rodents. The more basal multituberculates are found in a different suborder, "Plagiaulacida", a paraphyletic group containing all non cimolodontan multituberculates.

Formiciinae is an extinct subfamily of ants known from Eocene deposits in Europe and North America.

Hyopsodontidae is an extinct family of primitive mammals, initially assigned to the order Condylarthra, living from the Paleocene to the Eocene in North America and Eurasia. Condylarthra is now thought to be a wastebasket taxon; hyopsodontids have occasionally been speculated to be related to Afrotheria, but the most recent consensus is that they are related to Perissodactyla. Analysis of the inner ear shows shared characteristics with the Equoidea (horses and paleotheres); they may be a basal ungulate group near to perissodactyls.

Palaeoryctidae ("ancient diggers") is an extinct family of non-specialized eutherian mammals from extinct order Palaeoryctida, that lived in North America, Europe, Asia and Africa from the late Cretaceous to the middle Eocene.

Triisodontidae is an extinct, probably paraphyletic, or possibly invalid family of mesonychian placental mammals. Most triisodontid genera lived during the Paleocene in North America, but the genus Andrewsarchus (if it is a mesonychian, and not an artiodactyl) is known from the middle Eocene of Asia. Triisodontids were the first relatively large predatory mammals to appear in North America following the extinction of the non-bird dinosaurs. They differ from other mesonychian families in having less highly modified teeth.

Coryphodontidae is an extinct family of pantodont mammals known from the Late Paleocene to the Middle Eocene of Eurasia and North America.

Notharctidae is an extinct family of adapiform primates found primarily in North America and Europe.

Didolodontidae is a possibly paraphyletic family of "condylarth" mammals known from the Paleogene of South America, with most specimens known from Argentina. They were generally small-medium in body size, and had a bunodont dentition. A close relationship with litopterns has been suggested by some studies. They range in age from the early Paleocene (Selandian/Peligran) to late Eocene (Priabonian/Mustersan). The attribution of Salladolodus deuterotheroides from the Late Oligocene of Bolivia to the family is doubtful.

Numidotheriidae is an extinct family of primitive proboscideans that lived from the late Paleocene to the early Oligocene periods of North Africa.

Cercamoniinae is a subfamily within the extinct primate family Notharctidae primarily found in Europe, although a few genera have been found in North America and Africa.

Archaeopithecidae is an extinct family comprising two genera of notoungulate mammals, Teratopithecus and Archaeopithecus, both known from the Eocene of Argentina.

Oromerycidae is a small (both in size and diversity), extinct family of artiodactyls (even-toed hoofed mammals) closely related to living camels, known from the early to late Eocene of western North America.

Baenidae is an extinct family of paracryptodiran turtles known from the Early Cretaceous to Eocene of North America. While during the Early Cretaceous they are found across North America, during the Late Cretaceous they are only found in Laramidia, having disappeared from Appalachia. Most lineages survived the K-Pg Extinction, but the family was extinct by the latest Eocene. The name of the type genus, Baena, appears to be of Native American origin, likely from the Arapaho be’enoo. They are primarily found in freshwater deposits, and are considered to be aquatic, with a largely generalist habi

Planocraniidae is an extinct family of eusuchian crocodyliforms known from the Paleogene of Asia, Europe and North America. The family was coined by Li in 1976, and contains three genera, Boverisuchus, Duerosuchus and Planocrania. Planocraniids were highly specialized crocodyliforms that were adapted to living on land. They had extensive body armor, long legs, and blunt claws resembling hooves, and are sometimes informally called "hoofed crocodiles".

Ptilodontoidea is a group of extinct mammals from the Northern Hemisphere. They were generally small, somewhat rodent-like creatures of the extinct order Multituberculata.

The Sophiornithidae (literally "wisdom birds") are an extinct family of chicken-sized predatory birds that lived from the Paleocene to the Eocene periods of the Cenozoic, and were found primarily in Europe, and are thought to be primitive owls (hence, the name wisdom bird). They were also possibly related to Strigiformes.

Notharctinae is an extinct subfamily of primates that were common in North America during the early and middle Eocene (55-34 million years ago). The six genera that make up the group (Cantius, Pelycodus, Copelemur, Hesperolemur, Notharctus, and Smilodectes) contain species that are among the most primitive of the adapiform group, which is one of the most primitive groups of primates. The evolutionary history of this subfamily has been comparatively well documented and has been used to argue for evolutionary gradualism. Though it is generally accepted that adapiforms gave rise to modern day lem

Adapisoriculidae is an extinct family of non-placental eutherian mammals which was present during the Paleogene and possibly the Late Cretaceous. They were once thought to be members of the order Erinaceomorpha, closely related to the hedgehog family (Erinaceidae), because of their similar dentition, or to be basal Euarchontans. They were also thought to be marsupials at one point. Most recent studies show them to be non-placental eutherians, however.

Alagomyidae is a family of rodents known from the late Paleocene and early Eocene of Asia and North America (McKenna and Bell, 1997). Alagomyids have been identified as the most basal rodents, lying outside the common ancestry of living forms (Meng et al., 1994). Because of their phylogenetic position and their conservative dental morphology, alagomyids have played a key role in investigations of the origins and relationships of rodents (Meng et al., 1994; Meng and Wyss, 2001).

Eurymylidae is a family of extinct simplicidentates. Most authorities consider them to be basal to all modern rodents and suggest they may have been the ancestral stock from which the most recent common ancestor of all modern rodents (crown rodents) arose. However, the better-known eurymylids, including Eurymylus, Heomys, Matutinia, and Rhombomylus, appear to represent a monophyletic side branch that is that is that is not directly ancestral to rodents (Meng et al., 2003). Huang et al. (2004) have argued that Hanomys, Matutinia, and Rhombomylus form a clade characterized by distinctive feature

Basilosaurinae is a subfamily of cetaceans archaeocetes containing two genera: Basilosaurus and Basiloterus. They were characterized by elongated distal thoracic vertebrae, lumbar, and proximal sacrococcygeal. All known members of the subfamily are larger than their relatives of the Dorudontinae subfamily except Cynthiacetus.

thumb|left|Restoration of Haplohippus (middle right) and other animals of the Hancock Mammal Quarry Haplohippus is an extinct genus of the modern horse family Equidae, that lived in the Eocene, from 42 to 38 million years ago. Fossil remains of Haplohippus have been found in the Clarno Formation, part of the John Day Fossil Beds National Monument of the Northwestern United States. While Haplohippus is quite similar to Orohippus, it is considered more primitive in character than Epihippus.

Palaeoamasiidae or Palaeoamasinae is an extinct taxon of embrithopod mammals that have been found in Romania and Anatolia where they lived on the shores of the Tethys Ocean.

Andinichthyidae is a prehistoric family of basal catfishes from the Cretaceous to Eocene of South America.

Oldfieldthomasiidae is an extinct family of notoungulate mammals known from the Late Paleocene to Late Eocene of South America. The family was classified by George Gaylord Simpson in 1945 and a synonym is Acoelodidae, defined by Florentino Ameghino in 1901.

thumb|right|upright|Dinopanorpa megarche holotype Dinopanorpidae is a small family of extinct insects in the order Mecoptera (scorpionflies) that contains two genera and seven species.

Adapinae is a subfamily within the extinct primate family Adapidae, primarily found in Europe until the end of the Eocene. They are thought to have originated in Asia.

Palaeochiropterygidae is a family of extinct bats. It was originally erected by the Swiss naturalist Pierre Revilliod in 1917 after discoveries of Palaeochiropteryx fossils from the Messel Pit of Germany. Palaeochiropterygidae was merged into Archaeonycteridae by Kurten and Anderson in 1980, but modern authorities specializing in bat fossils maintain the distinction between the two. It was classified to the unranked clade Microchiropteramorpha by Smith et al. in 2007.

Palaeophiidae is an extinct family of marine snake within the infraorder Alethinophidia.

Eucosmodontidae is a poorly preserved family of fossil mammals within the extinct order Multituberculata. Representatives are known from strata dating from the Upper Cretaceous through the Lower Eocene of North America, as well as the Paleocene to Eocene of Europe. The family is part of the suborder of Cimolodonta. They might be related with the Djadochtatherioidea but without further finds, this remains unclear. Other than a partial snout, fossil evidence is limited to teeth. A 2021 study vindicates this relationship.