Palaeotheriidae is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

herbivorous A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...

perissodactyl Perissodactyla (, ), or odd-toed ungulates, is an order of Ungulate, ungulates. The order includes about 17 living species divided into three Family (biology), families: Equidae (wild horse, horses, Asinus, asses, and zebras), Rhinocerotidae ( ...

mammals that inhabited Europe, with less abundant remains also known from Asia, from the mid-Eocene to the early Oligocene. They are classified in

Equoidea Equoidea is a superfamily of hippomorph perissodactyls containing the Equidae, Palaeotheriidae, and other basal equoids of unclear affinities, of which members of the genus '' Equus'' are the only extant species. The earliest fossil record of ...

, along with the living family

Equidae Equidae (commonly known as the horse family) is the Taxonomy (biology), taxonomic Family (biology), family of Wild horse, horses and related animals, including Asinus, asses, zebra, zebras, and many extinct species known only from fossils. The fa ...

(which includes zebras, horses and asses).

Morphology

Palaeotheres ranged widely in size, from small species like '' Palaeotherium lautricense,'' which is estimated to have only weighed to large species like '' Palaeotherium magnum'', which are comparable in size to living equines, with body masses over . Their teeth are brachydont (low crowned). According to Danilo et al. 2013., paleotheriids are distinguished from other equoids by one unambiguous

synapomorphy In phylogenetics, an apomorphy (or derived trait) is a novel Phenotypic trait, character or character state that has evolution, evolved from its ancestral form (or Plesiomorphy and symplesiomorphy, plesiomorphy). A synapomorphy is an apomorphy sh ...

"the nasal notch opening distally to the canine, above the postcanine

diastema A diastema (: diastemata, from Greek , 'space') is a space or gap between two teeth. Many species of mammals have diastemata as a normal feature, most commonly between the incisors and molars. More colloquially, the condition may be referred to ...

" and two unambiguous character state changes "an average metaconule on he fourth premolar and "an oblique metastyle on he first and second molars.

Taxonomy

Palaeotheriidae is generally divided into the subfamilies Palaeotheriinae and 'Pachynolophinae'. The two groups are distinguished by the morphology of their upper molars, with mesostyles being at least moderately developed in those Palaeotheriinae, but generally weakly developed or absent in those of 'Pachylophinae'. 'Pachylophinae' is controversial with regards to its definition and phylogenetic placement. 'Pachylophinae', along with the genus '' Pachynolophus'' has been argued to be a

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

group that is ancestral to Palaeotheriinae.

Ecology

Early members of the family are suggested to have been

frugivore A frugivore ( ) is an animal that thrives mostly on raw fruits or succulent fruit-like produce of plants such as roots, shoots, nuts and seeds. Approximately 20% of mammalian herbivores eat fruit. Frugivores are highly dependent on the abundance ...

s, with later, larger members suggested to be

browsers Browse, browser, or browsing may refer to: Computing *Browser service, a feature of Microsoft Windows to browse shared network resources *Code browser, a program for navigating source code *File browser or file manager, a program used to manage f ...

Extinction

Evidence suggests that palaeotheriids went extinct in

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

during the Early Oligocene, approximately 33 Ma, as part of a faunal turnover event known as the

Grande Coupure Grande means "large" or "great" in many of the Romance languages. It may also refer to: Places * Grande, Germany, a municipality in Germany * Grande Communications, a telecommunications firm based in Texas * Grande-Rivière (disambiguation) * Ar ...

. The Eocene-Oligocene transition marked a significant global cooling event caused by the onset of Antarctic glaciation. This resulted in drier and more open habitats dominating the early Oligocene, and the loss of the dense forests that characterised the Eocene epoch. This environmental change, coupled with the arrival of new and better-adapted mammalian groups from Asia, triggered a decline in endemic European

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

groups such as Palaeotheriidae and Anoplotheriidae. In the

Hampshire Basin The Hampshire Basin is a geological basin of Palaeogene age in southern England, underlying parts of Hampshire, the Isle of Wight, Dorset, and Sussex. Like the London Basin to the northeast, it is filled with sands and clays of Paleocene and ...

of southern England the last record of Palaeotheriidae is from the Lower Hamstead Mbr. of the

Bouldnor Formation The Bouldnor Formation is a geological formation in the Hampshire Basin of southern England. It is the youngest formation of the Solent Group and was deposited during the uppermost Eocene and lower Oligocene. Stratotype and occurrence The Bo ...

, dating to approximately 33.6 Ma.

Fossil distribution

* Creechbarrow Hill Site,

Dorset Dorset ( ; Archaism, archaically: Dorsetshire , ) is a Ceremonial counties of England, ceremonial county in South West England. It is bordered by Somerset to the north-west, Wiltshire to the north and the north-east, Hampshire to the east, t ...

, England * Geiseltal, Mittelkohle, Zone III,

Saxony-Anhalt Saxony-Anhalt ( ; ) is a States of Germany, state of Germany, bordering the states of Brandenburg, Saxony, Thuringia and Lower Saxony. It covers an area of and has a population of 2.17 million inhabitants, making it the List of German states ...

, Germany *Egerkingen, Alpha & Beta fissures,

Baselland Canton of Basel-Landschaft or Basel-Country, informally known as Baselland or Baselbiet (; ; ; ; ), is one of the 26 cantons forming the Swiss Confederation. It is composed of five districts and its capital city is Liestal. It is traditional ...

, Switzerland *La Debruge,

Provence-Alpes-Côte d'Azur Provence-Alpes-Côte d'Azur (commonly shortened to PACA), also known as Région Sud, is one of the eighteen Regions of France, administrative regions of France, located at the far southeastern point of the Metropolitan France, mainland. The main P ...

Region,

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

*The

Caucasus Mountains The Caucasus Mountains * * Azerbaijani: , * * * * * * * * * * * is a mountain range at the intersection of Asia and Europe. Stretching between the Black Sea and the Caspian Sea, they are surrounded by the Caucasus region ...

Georgia Georgia most commonly refers to: * Georgia (country), a country in the South Caucasus * Georgia (U.S. state), a state in the southeastern United States Georgia may also refer to: People and fictional characters * Georgia (name), a list of pe ...

References