Palaeotheriidae

{{Short description|Extinct family of mammals}} {{More citations needed|date=July 2023}} {{Automatic taxobox | fossil_range = {{Fossil range|55|28}}Early Eocene to early Oligocene | image = Palaeotherium_magnum_skeleton_reconstruction_1922.png | image_caption = ''Palaeotherium magnum'' skeleton | image2 = Plagiolophus_1.JPG | image2_caption = Fossil of ''Plagiolophus'' | taxon = Palaeotheriidae | authority = Bonaparte, 1850 | subdivision_ranks = Genera | subdivision = * '''Pachynolophinae''' ** ''Anchilophus'' ** ''Bepitherium'' ** ''Eurohippus'' ** ''Hyracotherium'' ** ''Lijiangia'' ** ''Lophiohippus'' ** ''Lophiotherium'' ** ''Metanchilophus'' ** ''Orolophus'' ** ''Pachynolophus'' ** ''Paranchilophus'' ** ''Propalaeotherium''<ref>{{cite journal|last1=Remy|first1=Jean A.|last2=Krasovec|first2=Gabriel|last3=Marandat|first3=Bernard|year=2016|title=A new species of Propalaeotherium (Palaeotheriidae, Perissodactyla, Mammalia) from the Middle Eocene locality of Aumelas (Hérault, France)|journal=Palaeovertebrata|volume=40|issue=2|article-number=e1 |doi=10.18563/pv.40.2.e1}}</ref> ** ''Qianohippus'' * '''Palaeotheriinae''' ** ''Cantabrotherium'' ** ''Iberolophus'' ** ''Idiodontherium''<ref name="Perales-Gogenola2023">{{cite journal |last1=Perales-Gogenola |first1=L. |last2=Badiola |first2=A. |last3=Gómez-Olivencia |first3=A. |last4=Pereda-Suberbiola |first4=X. |title=A remarkable new paleotheriid (Mammalia) in the endemic Iberian Eocene perissodactyl fauna |journal=Journal of Vertebrate Paleontology |date=2023 |volume=42 |issue=4 |article-number=e2189447 |doi=10.1080/02724634.2023.2189447|bibcode=2022JVPal..42E9447P |s2cid=258663753 }}</ref> ** ''Leptolophus'' ** ''Mekodontherium'' ** ''Metaplagiolophus'' ** ''Palaeotherium'' ** ''Paraplagiolophus'' ** ''Plagiolophus'' ** ''Pseudopalaeotherium'' | synonyms = Pachynolophidae <small>Pavlow, 1888</small> }}

'''Palaeotheriidae''' is an extinct family of herbivorous perissodactyl mammals that inhabited Europe, with less abundant remains also known from Asia,<ref name="Bai-2017">{{Cite journal |last=Bai |first=Bin |date=November 2017 |editor-last=Hautier |editor-first=Lionel |title=Eocene Pachynolophinae (Perissodactyla, Palaeotheriidae) from China, and their palaeobiogeographical implications |journal=Palaeontology |language=en |volume=60 |issue=6 |pages=837–852 |doi=10.1111/pala.12319 |issn=0031-0239|doi-access=free |bibcode=2017Palgy..60..837B }}</ref> from the mid-Eocene to the early Oligocene. They are classified in Equoidea, along with the living family Equidae (which includes zebras, horses and asses).<ref>{{Cite journal |last1=Perales-Gogenola |first1=Leire |last2=Badiola |first2=Ainara |last3=Gómez-Olivencia |first3=Asier |last4=Pereda-Suberbiola |first4=Xabier |date=2021-01-02 |title=New Leptolophus (Palaeotheriidae) species from the Iberian Peninsula and early evidence of hypsodonty in an Eocene perissodactyl |url=https://www.tandfonline.com/doi/full/10.1080/02724634.2021.1912061 |journal=Journal of Vertebrate Paleontology |language=en |volume=41 |issue=1 |article-number=e1912061 |doi=10.1080/02724634.2021.1912061 |bibcode=2021JVPal..41E2061P |issn=0272-4634|url-access=subscription }}</ref>

==Morphology== [[File:Paleotherium magnum.jpg|left|thumb|Life restoration of ''Palaeotherium magnum'']] [[File:Palaeotherium size comparison.png|left|thumb|Size comparison show the range of size of various species of ''Palaeotherium'']] Palaeotheres ranged widely in size, from small species like ''Palaeotherium lautricense,'' which is estimated to have only weighed {{cvt|36|kg}}<ref name="robiac">{{cite journal |last=Remy |first=Jean-Albert |year=2015 |title=Les Périssodactyles (Mammalia) du gisement Bartonien supérieur de Robiac (Éocène moyen du Gard, Sud de la France) |journal=Palaeovertebrata |volume=39 |pages=1–98 |doi=10.18563/pv.39.1.e3 |number=1}}</ref> to large species like ''Palaeotherium magnum'', which are comparable in size to living equines, with body masses over {{cvt|200|kg}}.<ref name="forelimb">{{cite journal |last1=MacLaren |first1=Jamie A. |last2=Nauwelaerts |first2=Sandra |year=2020 |title=Modern tapirs as morphofunctional analogues for locomotion in endemic Eocene European perissodactyls |url=https://www.researchgate.net/publication/331178250 |journal=Journal of Mammalian Evolution |volume=27 |issue=2 |pages=245–263 |doi=10.1007/s10914-019-09460-1}}</ref> Their teeth are brachydont (low crowned).<ref name="Engels-2019">{{Cite journal |last1=Engels |first1=Sandra |last2=Schultz |first2=Julia A. |date=June 2019 |title=Evolution of the power stroke in early Equoidea (Perissodactyla, Mammalia) |url=http://link.springer.com/10.1007/s12549-018-0341-4 |journal=Palaeobiodiversity and Palaeoenvironments |language=en |volume=99 |issue=2 |pages=271–291 |doi=10.1007/s12549-018-0341-4 |bibcode=2019PdPe...99..271E |issn=1867-1594|url-access=subscription }}</ref> According to Danilo et al. 2013., paleotheriids are distinguished from other equoids by one unambiguous synapomorphy "the nasal notch opening distally to the canine, above the postcanine diastema" and two unambiguous character state changes "an average metaconule on [the fourth premolar]" and "an oblique metastyle on [the first and second molars]".<ref name="Danilo-2013">{{Cite journal |last1=Danilo |first1=Laure |last2=Remy |first2=Jean A. |last3=Vianey-Liaud |first3=Monique |last4=Marandat |first4=Bernard |last5=Sudre |first5=Jean |last6=Lihoreau |first6=Fabrice |date=January 2013 |title=A new Eocene locality in southern France sheds light on the basal radiation of Palaeotheriidae (Mammalia, Perissodactyla, Equoidea) |url=http://www.tandfonline.com/doi/abs/10.1080/02724634.2012.711404 |journal=Journal of Vertebrate Paleontology |language=en |volume=33 |issue=1 |pages=195–215 |doi=10.1080/02724634.2012.711404 |bibcode=2013JVPal..33..195D |issn=0272-4634|url-access=subscription }}</ref>

== 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.<ref name="Bai-2017" /> 'Pachylophinae', along with the genus ''Pachynolophus'' has been argued to be a paraphyletic group that is ancestral to Palaeotheriinae.<ref name="Danilo-2013" /><ref name="Bai-2017" />

== Ecology == Early members of the family are suggested to have been frugivores, with later, larger members suggested to be browsers.<ref name="Engels-2019" />

==Extinction==

Evidence suggests that palaeotheriids went extinct in Eurasia during the Early Oligocene, approximately 33 Ma, as part of a faunal turnover event known as the Grande Coupure. 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 groups such as Palaeotheriidae and Anoplotheriidae. In the Hampshire Basin of southern England the last record of Palaeotheriidae is from the Lower Hamstead Mbr. of the Bouldnor Formation, dating to approximately 33.6 Ma.

==Fossil distribution== *Creechbarrow Hill Site, Dorset, England *Geiseltal, Mittelkohle, Zone III, Saxony-Anhalt, Germany *Egerkingen, Alpha & Beta fissures, Baselland, Switzerland *La Debruge, Provence-Alpes-Côte d'Azur Region, France *The Caucasus Mountains in Georgia

==See also== * Evolution of the horse

==References== {{Reflist}}

Category:Palaeotheriidae Category:Prehistoric horses Category:Eocene first appearances Category:Oligocene extinctions Category:Prehistoric mammal families Category:Fossil taxa described in 1850