{{short description|Family of extinct mammals}} {{Automatic taxobox | fossil_range = Oligocene to early Pleistocene ~{{Fossil range|33.9|1.0}} {{Period fossil range|Cenozoic|33.9|1.0}} | image = Moropus.jpg | image_caption = ''Moropus elatus'' (Schizotheriinae) at the<br />National Museum of Natural History, <br />Washington, DC | image2 = Anisodon grande models.jpg | image2_caption = Life restoration of ''Anisodon'' (Chalicotheriinae) | taxon = Chalicotheriidae | authority = Gill, 1872<ref name="Gill, 1872"/> | type_genus = {{extinct}}''Chalicotherium'' | type_genus_authority = Kaup, 1833 | subdivision_ranks = Subfamilies | subdivision = *†Chalicotheriinae {{small|Gill, 1872}} **†''Anisodon'' **†''Chalicotherium'' **†''Iriritherium'' **†''Kalimantsia'' **†''Hesperotherium'' **†''Nestoritherium'' **†''Winamia'' *†Schizotheriinae {{small|Holland and Peterson, 1914}} **†''Ancylotherium'' **†''Borissiakia'' **†''Chemositia'' **†''Metaschizotherium'' **†''Moropus'' **†''Phyllotillon'' **†''Schizotherium'' **†''Tylocephalonyx'' }}
'''Chalicotheriidae''' (from Ancient Greek χάλιξ (''khálix''), meaning "gravel", and θηρίον (''theríon''), meaning "beast") is an extinct family of herbivorous, perissodactyl mammals. Unlike living odd-toed ungulates, '''chalicotheres''' bore large claws on their hands rather than hooves, thought to have been used for grasping vegetation, with their dentition being adapted for browsing. The family is known from the Oligocene to the Pleistocene, reached its greatest diversity in the Miocene, and is known from Asia, Europe, Africa and North America. Asia appears to have been the main centre of diversification for the group.<ref name="CoombsCote2010">{{cite book |last1=Coombs |first1=Margery C. |last2=Cote |first2=Susanne M. |chapter=Chalicotheriidae |title=Cenozoic Mammals of Africa |year=2010 |pages=659–668}}</ref><ref name="Kampouridis2023">{{cite journal |last1=Kampouridis |first1=Panagiotis |last2=Rățoi |first2=Bogdan Gabriel |last3=Ursachi |first3=Laurențiu |title=New evidence for the unique coexistence of two subfamilies of clawed perissodactyls (Mammalia, Chalicotheriidae) in the Upper Miocene of Romania and the Eastern Mediterranean |journal=Journal of Mammalian Evolution |year=2023 |volume=30 |pages=641–656 |doi=10.1007/s10914-023-09657-5}}</ref>
Chalicotheriids are usually divided into two subfamilies, '''Chalicotheriinae''' and '''Schizotheriinae''', which differed in the skull, teeth and limbs.<ref name="CoombsCote2010" /> Chalicotheriines generally had much longer forelimbs than hindlimbs and are usually interpreted as more specialised browsers of wooded habitats, whereas schizotheriines had more even limb proportions and appear to have occupied a broader range of environments. Derived schizotheriines also developed the distinctive fused phalanges known as the ''duplex bone''.<ref name="Kampouridis2023" />
Microwear and mesowear studies indicate that chalicotheriids were browsers rather than grazers, feeding mainly on leaves and also on tougher plant foods such as bark, twigs, and in some taxa fruit or other hard items. Their unusual claws are therefore generally interpreted as part of a specialised browsing adaptation rather than evidence of a primarily digging lifestyle.<ref name="Kampouridis2023" /><ref name="Semprebon2011">{{cite journal |last1=Semprebon |first1=Gina M. |last2=Sise |first2=Paul J. |last3=Coombs |first3=Margery C. |title=Potential Bark and Fruit Browsing as Revealed by Stereomicrowear Analysis of the Peculiar Clawed Herbivores Known as Chalicotheres (Perissodactyla, Chalicotherioidea) |journal=Journal of Mammalian Evolution |year=2011 |volume=18 |issue=1 |pages=33–55 |doi=10.1007/s10914-010-9149-3}}</ref><ref name="Tsoukala2022">{{cite book |last=Tsoukala |first=Evangelia |chapter=The Fossil Record of Chalicotheres (Mammalia: Perissodactyla: Chalicotheriidae) in Greece |editor-last=Vlachos |editor-first=Evangelos |title=Fossil Vertebrates of Greece Vol. 2 |publisher=Springer International Publishing |place=Cham |year=2022 |pages=501–517 |doi=10.1007/978-3-030-68442-6_15}}</ref>
== History of discovery ==
The history of chalicothere research began in the early nineteenth century with the discovery of ungual phalanges near Eppelsheim in Germany. In 1822, Georges Cuvier interpreted these unusual claw bones as belonging to a gigantic pangolin. Johann Jakob Kaup later described chalicothere teeth from the same locality as the new genus ''Chalicotherium'' in 1833, but did not recognise that the teeth and claws belonged to the same kind of animal.<ref name="Anquetin-2007">{{Cite journal |last1=Anquetin |first1=JéRéMy |last2=Antoine |first2=Pierre-Olivier |last3=Tassy |first3=Pascal |date=November 2007 |title=Middle Miocene Chalicotheriinae (Mammalia, Perissodactyla) from France, with a discussion on chalicotheriine phylogeny |url=https://academic.oup.com/zoolinnean/article-lookup/doi/10.1111/j.1096-3642.2007.00327.x |journal=Zoological Journal of the Linnean Society |language=en |volume=151 |issue=3 |pages=577–608 |doi=10.1111/j.1096-3642.2007.00327.x |issn=1096-3642}}</ref>
The Miocene locality of Sansan in southern France played a central role in clarifying the nature of chalicotheres. Fossils from Sansan included postcranial remains named ''Macrotherium'' by Édouard Lartet in 1837 and cranial remains later referred by de Blainville to ''Anoplotherium'' in the 1840s. It was only after the discovery and description of a more complete skeleton by Henri Filhol in 1890 that the skull, teeth and unusual limb bones were firmly recognised as belonging to the same animal.<ref name="Anquetin-2007" />
Later work helped to resolve the complicated nomenclature of the classic European material, including the status of ''Macrotherium'' and the use of the name ''Anisodon'' for the Sansan chalicotheriines.<ref name="Anquetin-2007" /> Because of their unusual combination of claws, browsing dentition and highly distinctive limb proportions, chalicotheres also became a notable case in the history of palaeontology, illustrating how difficult some fossil mammals were to reconstruct and compare with living animals.<ref name="Manias2018">{{cite journal |last=Manias |first=Chris |title=Reconstructing an incomparable organism: the Chalicothere in nineteenth- and early-twentieth century palaeontology |journal=History and Philosophy of the Life Sciences |year=2018 |volume=40 |issue=1 |page=22 |doi=10.1007/s40656-018-0187-0}}</ref>
== Description and functional morphology == [[Image:ChalicotheriumDB1.jpg|thumb|left|Life restoration of the chalicotheriine ''Anisodon grande'', formerly ''Chalicotherium grande''.]] Chalicotheriids were unusual among Perissodactyla in possessing large claws rather than hooves. Despite this, their dentition was that of browsing herbivores: the cheek teeth were low-crowned, and the lower incisors cropped vegetation against a toothless pad in the upper jaw.<ref name="Coombs1983">{{cite journal |last=Coombs |first=Margery C. |title=Large Mammalian Clawed Herbivores: A Comparative Study |journal=Transactions of the American Philosophical Society |year=1983 |volume=73 |issue=7 |pages=1–96 |doi=10.2307/3137420}}</ref><ref name="Li2022">{{cite journal |last1=Li |first1=Zhaoyu |last2=Mörs |first2=Thomas |last3=Zhang |first3=Yunxiang |last4=Xie |first4=Kun |last5=Li |first5=Yongxiang |title=New Material of Schizotheriine Chalicothere (Perissodactyla, Chalicotheriidae) from the Xianshuihe Formation (Early Miocene) of Lanzhou Basin, Northwest China |journal=Journal of Mammalian Evolution |year=2022 |volume=29 |pages=877–889 |doi=10.1007/s10914-022-09619-3}}</ref> Chalicotheriids ranged in size from small antelope-sized forms to animals comparable to large draft horses.<ref name="COOMBS-2013">{{Cite journal|last=Coombs|first=Margery C.| title=A Juvenile Mandible with Deciduous Teeth of Ancylotherium Pentelicum (Perissodactyla, Chalicotheriidae, Schizotheriinae), Collected by Barnum Brown from the Late Miocene of Samos (Greece) |date=2013|journal=Journal of Vertebrate Paleontology|volume=33|issue=1|pages=233–238| doi=10.1080/02724634.2012.710281 | jstor=23361086 |bibcode=2013JVPal..33..233C | s2cid=85723812 |issn=0272-4634}}</ref> The family is generally divided into two subfamilies, Chalicotheriinae and Schizotheriinae, which differ in the skull, teeth, and appendicular skeleton.<ref name="Li2022" /><ref name="Kampouridis2025">{{cite journal |last1=Kampouridis |first1=Panagiotis |last2=Coombs |first2=Margery C. |last3=Rössner |first3=Georg-D. |title=Unique pathological phalangeal fusion in the chalicothere subfamily Chalicotheriinae and the interphalangeal immobilization in chalicotheres |journal=Die Naturwissenschaften |year=2025 |volume=112 |issue=7 |page=49 |doi=10.1007/s00114-025-02011-0 |pmid=40824454}}</ref>
=== Skull and dentition ===
The skull and lower jaw differed noticeably between the two subfamilies. Schizotheriines generally had more slender mandibles, a tapered anterior horizontal ramus, and a relatively low symphysis, whereas chalicotheriines tended to have more robust jaws and, in at least some species, a longer diastema and a fuller complement of lower anterior teeth.<ref name="Li2022" /><ref name="LiuZhang2012">{{cite journal |last1=Liu |first1=Yan |last2=Zhang |first2=Zhaoqun |title=New materials of ''Chalicotherium brevirostris'' (Perissodactyla, Chalicotheriidae) from the Tunggur Formation, Inner Mongolia |journal=Geobios |year=2012 |volume=45 |issue=4 |pages=369–376 |doi=10.1016/j.geobios.2011.10.011}}</ref> New mandibular material of ''Chalicotherium brevirostris'' showed that this species had a long snout, a long diastema, and three lower incisors plus a canine, revising earlier assumptions based on more fragmentary material.<ref name="LiuZhang2012" />
=== Forelimbs, claws, and stance ===
The forelimbs were the most distinctive part of chalicothere anatomy. Coombs interpreted chalicotheres as a perissodactyl lineage specialised for browsing on higher vegetation, with the hook-like manual digits used to pull branches within reach of the mouth rather than primarily for digging.<ref name="Coombs1983" /> Schizotheriines retained more even limb proportions and were probably more typical quadrupedal browsers, although they also show adaptations consistent with rearing and branch-pulling.<ref name="Coombs1983" /> In derived schizotheriines, the proximal and middle phalanges of the second manual digit fused to form the distinctive duplex bone.<ref name="Kampouridis2025" /> This fusion immobilised the joint and is one of the clearest specialisations of the schizotheriine manus.<ref name="Kampouridis2025" /> Chalicotheriines were more specialised in the forelimb, with proportionally longer forelimbs and a more unusual manus. A knuckle-supported forelimb stance has often been reconstructed for forms such as ''Chalicotherium'', but this should be treated as an interpretation rather than an absolutely settled fact.<ref name="Coombs1983" /> Recent work has suggested that both chalicothere subfamilies evolved ways of limiting movement in the digits, but that schizotheriines did so through regular phalangeal fusion, whereas chalicotheriines achieved digit immobilisation through a different joint structure rather than formation of a true duplex bone.<ref name="Kampouridis2025" />
=== Hindlimbs and posture ===
The hindlimbs and pelvis also differed between the two subfamilies. Schizotheriines had powerful hindlimbs and a body plan compatible with rearing while feeding, whereas chalicotheriines combined their elongated forelimbs with a postcranial skeleton that has often been interpreted as supporting upright and possibly seated feeding postures.<ref name="Coombs1983" /> These reconstructions are based on comparative functional morphology and are best treated as well-supported interpretations rather than direct observations of behaviour.<ref name="Coombs1983" />
=== Subfamily contrasts ===
Taken together, the two chalicothere subfamilies represent different anatomical solutions to clawed browsing. Schizotheriines retained a more conventional quadrupedal stance and appear to have been functionally less specialised, while chalicotheriines evolved a more extreme forelimb-dominated body plan with greater emphasis on forelimb reach and branch manipulation.<ref name="Coombs1983" /><ref name="Li2022" /><ref name="Kampouridis2025" />
== Palaeobiology ==
=== Diet ===
Dental microwear and mesowear studies indicate that chalicotheriids were browsers rather than grazers, and that grass did not form a significant part of their diet.<ref name="Semprebon2011">{{cite journal |last1=Semprebon |first1=Gina M. |last2=Sise |first2=Paul J. |last3=Coombs |first3=Margery C. |title=Potential Bark and Fruit Browsing as Revealed by Stereomicrowear Analysis of the Peculiar Clawed Herbivores Known as Chalicotheres (Perissodactyla, Chalicotherioidea) |journal=Journal of Mammalian Evolution |year=2011 |volume=18 |issue=1 |pages=33–55 |doi=10.1007/s10914-010-9149-3}}</ref> The family as a whole appears to have fed mainly on leaves, but different genera also show evidence for tougher or more abrasive browse, including bark, twigs, and fruit with hard seeds or pits.<ref name="Semprebon2011" />
The two subfamilies do not seem to have been identical in diet. North American schizotheriines such as ''Moropus'' and ''Tylocephalonyx'' have microwear consistent mainly with leaf browsing, in some cases with a greater contribution from bark and twigs.<ref name="Semprebon2011" /> By contrast, several European chalicotheriines, especially ''Anisodon'' and ''Chalicotherium'', show unusually abrasive microwear for brachydont browsers, suggesting regular consumption of resistant browse or hard fruit items rather than especially soft vegetation.<ref name="Semprebon2011" /> This is important because it contradicts the older assumption that chalicotheriines necessarily had the softest diets in the family.<ref name="Semprebon2011" />
Diet could also vary within the family by genus and region. ''Metaschizotherium'' shows evidence of more fruit-browsing than ''Moropus'', while the late Miocene ''Anisodon'' from Dorn-Dürkheim most likely fed on leaves and fruit, with no indication of substantial grit, dust, or grass in the diet.<ref name="Semprebon2011" /><ref name="Fahlke2013">{{cite journal |last1=Fahlke |first1=Julia M. |last2=Coombs |first2=Margery C. |last3=Semprebon |first3=Gina M. |title=Anisodon sp. (Mammalia, Perissodactyla, Chalicotheriidae) from the Turolian of Dorn-Dürkheim 1 (Rheinhessen, Germany): morphology, phylogeny, and palaeoecology of the latest chalicothere in Central Europe |journal=Palaeobiodiversity and Palaeoenvironments |year=2013 |volume=93 |pages=151–170 |doi=10.1007/s12549-013-0119-7}}</ref>
=== Locomotion and feeding posture ===
Functional interpretations of the postcranial skeleton indicate that chalicotheriids used their claws primarily in feeding rather than as digging tools.<ref name="Coombs1983">{{cite journal |last=Coombs |first=Margery C. |title=Large Mammalian Clawed Herbivores: A Comparative Study |journal=Transactions of the American Philosophical Society |year=1983 |volume=73 |issue=7 |pages=1–96 |doi=10.2307/3137420}}</ref> Coombs interpreted the family as a lineage of specialised browsing perissodactyls in which the forelimbs and hooked claws were used to pull branches within reach of the mouth.<ref name="Coombs1983" />
Schizotheriines retained more even forelimb and hindlimb proportions and are generally interpreted as the less specialised of the two subfamilies.<ref name="Coombs1983" /><ref name="Li2022">{{cite journal |last1=Li |first1=Zhaoyu |last2=Mörs |first2=Thomas |last3=Zhang |first3=Yunxiang |last4=Xie |first4=Kun |last5=Li |first5=Yongxiang |title=New Material of Schizotheriine Chalicothere (Perissodactyla, Chalicotheriidae) from the Xianshuihe Formation (Early Miocene) of Lanzhou Basin, Northwest China |journal=Journal of Mammalian Evolution |year=2022 |volume=29 |pages=877–889 |doi=10.1007/s10914-022-09619-3}}</ref> Their powerful hindlimbs and pelvic morphology suggest that at least some could rear up while feeding, using the claws of the forelimbs to draw down branches.<ref name="Coombs1983" /> Chalicotheriines developed a more extreme body plan, with much longer forelimbs and more unusual forefoot mechanics. A knuckle-supported or otherwise specialised forelimb stance has often been reconstructed for forms such as ''Chalicotherium'', but this is best presented as a functional interpretation rather than a directly observed certainty.<ref name="Coombs1983" /><ref name="Kampouridis2024">{{cite journal |last1=Kampouridis |first1=Panagiotis |title=Disparate occurrences of a chalicotheriine and a schizotheriine chalicothere (Mammalia, Chalicotheriidae) at the Late Miocene hominid locality Hammerschmiede (Germany) |journal=PalZ |year=2024 |volume=98 |pages=313–329 |doi=10.1007/s12542-024-00685-x}}</ref>
=== Habitat ===
Chalicotheriids are generally associated with wooded habitats, but the family did not occupy a single environment throughout its history.<ref name="Coombs1983" /><ref name="Semprebon2011" /> Evidence from the early Miocene of the Lanzhou Basin suggests that schizotheriines such as ''Borissiakia'' lived in at least partly open woodland under relatively humid conditions.<ref name="Li2022" /> Other schizotheriines are associated with forest, woodland, or treed habitats, including more open settings than are usually reconstructed for chalicotheriines.<ref name="Kampouridis2024" />
Chalicotheriines are more often linked to denser or more closed habitats, but the evidence is more nuanced than the older claim that they lived only in moist closed-canopy forest.<ref name="Coombs1983" /><ref name="Chavasseau2010">{{cite journal |last1=Chavasseau |first1=Olivier |last2=Chaimanee |first2=Yaowalak |last3=Yamee |first3=Chotima |last4=Tun |first4=Soe Aung Naing |last5=Marandat |first5=Bernard |title=First Record of a Chalicothere from the Miocene of Myanmar |journal=Acta Palaeontologica Polonica |year=2010 |volume=55 |issue=1 |pages=13–22 |doi=10.4202/app.2009.0033}}</ref> A chalicotheriine from the Miocene of Myanmar has been used to support the presence of an important closed-habitat component in the local palaeoenvironment, while the latest Central European ''Anisodon'' from Dorn-Dürkheim comes from a tropical savannah-to-woodland setting rather than a dense forest sensu stricto.<ref name="Chavasseau2010" /><ref name="Fahlke2013" /> Recent work on Romanian and German localities has argued that the two chalicothere subfamilies probably differed in preferred environments, with schizotheriines plausibly more tolerant of open settings and chalicotheriines preferring denser, more wooded habitats.<ref name="Kampouridis2024" /><ref name="Kampouridis2023">{{cite journal |last1=Kampouridis |first1=Panagiotis |last2=Rățoi |first2=Bogdan Gabriel |last3=Ursachi |first3=Laurențiu |title=New evidence for the unique coexistence of two subfamilies of clawed perissodactyls (Mammalia, Chalicotheriidae) in the Upper Miocene of Romania and the Eastern Mediterranean |journal=Journal of Mammalian Evolution |year=2023 |volume=30 |pages=641–656 |doi=10.1007/s10914-023-09657-5}}</ref>
=== Possible behaviour ===
Direct evidence for chalicothere behaviour is limited, so most reconstructions are inferential.<ref name="Coombs1983" /> The best-supported behavioural interpretations are feeding-related: branch-pulling with the forelimbs, rearing in at least some schizotheriines, and more orthograde or specialised feeding postures in chalicotheriines.<ref name="Coombs1983" />
Evidence for social structure is much weaker. Chalicotheres are generally rare elements in many fossil assemblages, and some species show marked size variation that has been interpreted as sexual dimorphism; this is well documented in ''Moropus elatus'' and has also been discussed for other taxa.<ref name="Coombs1975">{{cite journal |last=Coombs |first=Margery C. |title=Sexual Dimorphism in Chalicotheres (Mammalia, Perissodactyla) |journal=Systematic Zoology |year=1975 |volume=24 |issue=1 |pages=55–62 |doi=10.2307/2412697}}</ref><ref name="Kampouridis2024" /> However, rarity in the fossil record does not by itself demonstrate solitary behaviour, and there is currently no secure basis for reconstructing detailed social systems across the family.<ref name="Kampouridis2024" />
== Systematics and taxonomy == Chalicotheres are part of the order Perissodactyla, which includes modern equines, rhinoceroses, and tapirs, as well as extinct relatives like brontotheres.<ref name="MamEv2">{{cite book |author1=Savage, RJG |url=https://archive.org/details/mammalevolutioni0000sava |title=Mammal Evolution: an illustrated guide |author2=Long, MR |publisher=Facts on File |year=1986 |isbn=0-8160-1194-X |location=New York |pages=[https://archive.org/details/mammalevolutioni0000sava/page/198 198–199] |url-access=registration}}</ref> As the early evolution of perissodactyls is still unresolved, their closest relatives among other perissodactyl groups is obscure.<ref>{{Cite journal |last1=Holbrook |first1=Luke T. |last2=Lucas |first2=Spencer G. |last3=Emry |first3=Robert J. |date=2004 |title=Skulls of the Eocene Perissodactyls (Mammalia) "Homogalax" and "Isectolophus" |journal=Journal of Vertebrate Paleontology |volume=24 |issue=4 |pages=951–956 |doi=10.1671/0272-4634(2004)024[0951:SOTEPM]2.0.CO;2 |issn=0272-4634 |jstor=4524789 |s2cid=86289060}}</ref> They are generally placed as part of the clade Ancylopoda alongside their close relatives Lophiodontidae. Many studies considered them as closer to Ceratomorpha (which includes tapirs and rhinoceroses) than Equoidea.<ref>{{Cite journal |last=Froehlich |first=David J. |date=1999 |title=Phylogenetic Systematics of Basal Perissodactyls |journal=Journal of Vertebrate Paleontology |volume=19 |issue=1 |pages=140–159 |bibcode=1999JVPal..19..140F |doi=10.1080/02724634.1999.10011129 |issn=0272-4634 |jstor=4523976}}</ref><ref>{{Citation |last=Tsoukala |first=Evangelia |title=The Fossil Record of Chalicotheres (Mammalia: Perissodactyla: Chalicotheriidae) in Greece |date=2022 |work=Fossil Vertebrates of Greece Vol. 2 |pages=501–517 |editor-last=Vlachos |editor-first=Evangelos |url=https://link.springer.com/10.1007/978-3-030-68442-6_15 |access-date=2024-08-22 |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/978-3-030-68442-6_15 |isbn=978-3-030-68441-9|url-access=subscription }}</ref> A 2004 cladistic study alternatively recovered Ancylopoda as sister to all modern perissodactyls (which includes Equoidea and Ceratomorpha), with the brontotheres as the most distantly related within the order Perissodactyla.<ref>{{Cite journal |last1=Hooker |first1=J. J. |last2=Dashzeveg |first2=D. |date=2004 |title=The origin of chalicotheres (Perissodactyla, Mammalia) |journal=Palaeontology |language=en |volume=47 |issue=6 |pages=1363–1386 |bibcode=2004Palgy..47.1363H |doi=10.1111/j.0031-0239.2004.00421.x |issn=1475-4983 |s2cid=83720739 |doi-access=free}}</ref>
Chalicotheriidae is the family that includes the Oligocene and later chalicotheres, and it is generally divided into two subfamilies, '''Chalicotheriinae''' and '''Schizotheriinae'''. This division is based chiefly on cranial, dental and postcranial characters. Chalicotheriines typically have more robust jaws, a longer mandibular symphysis, low-crowned cheek teeth and the retention of lower canines, whereas schizotheriines generally have more slender mandibles, a shorter symphysis and more derived cheek teeth.<ref name="Li2022">{{cite journal |last1=Li |first1=Zhaoyu |last2=Mörs |first2=Thomas |last3=Zhang |first3=Yunxiang |last4=Xie |first4=Kun |last5=Li |first5=Yongxiang |title=New Material of Schizotheriine Chalicothere (Perissodactyla, Chalicotheriidae) from the Xianshuihe Formation (Early Miocene) of Lanzhou Basin, Northwest China |journal=Journal of Mammalian Evolution |year=2022 |volume=29 |pages=877–889 |doi=10.1007/s10914-022-09619-3}}</ref><ref name="CoombsCote2010">{{cite book |last1=Coombs |first1=Margery C. |last2=Cote |first2=Susanne M. |chapter=Chalicotheriidae |title=Cenozoic Mammals of Africa |year=2010 |pages=659–668}}</ref>
Recent treatments place ''Winamia'', ''Chalicotherium'', ''Kalimantsia'', ''Anisodon'', ''Nestoritherium'' and ''Hesperotherium'' in the Chalicotheriinae.<ref name="Li2022" /> Classification within the subfamily has long been debated, however, and revisions have altered the status of several classic names. A nomenclatural review supported ''Anisodon'' as the appropriate genus for the Sansan species traditionally associated with ''Chalicotherium'' and ''Macrotherium'', and a cladistic analysis of middle and late Miocene chalicotheriines recovered two main clades while also noting that the relationships of the group remain unstable pending revision of earlier taxa and the addition of more postcranial data.<ref name="Anquetin2007">{{cite journal |last1=Anquetin |first1=Jérémy |last2=Antoine |first2=Pierre-Olivier |last3=Tassy |first3=Pascal |title=Middle Miocene Chalicotheriinae (Mammalia, Perissodactyla) from France, with a discussion on chalicotheriine phylogeny |journal=Zoological Journal of the Linnean Society |year=2007 |volume=151 |issue=3 |pages=577–608 |doi=10.1111/j.1096-3642.2007.00327.x}}</ref> Later work revalidated ''Nestoritherium'' and suggested that ''Hesperotherium'' may be nested within it.<ref name="Chen2012">{{cite journal |last1=Chen |first1=Shao-Kun |last2=Deng |first2=Tao |last3=He |first3=Wen |last4=Chen |first4=Shan-Qin |title=A new species of Chalicotheriinae (Perissodactyla, Mammalia) from the Late Miocene in the Linxia Basin of Gansu, China |journal=Vertebrata PalAsiatica |year=2012 |volume=50 |issue=1 |pages=53–73}}</ref>
Schizotheriinae includes ''Schizotherium'', ''Borissiakia'', ''Phyllotillon'', ''Moropus'', ''Tylocephalonyx'', ''Metaschizotherium'' and ''Ancylotherium''.<ref name="Li2022" /> Recent authors continue to follow the broad framework established by Margery Coombs for the diagnosis and internal relationships of the subfamily.<ref name="Li2022" /> Some names within the group remain problematic: for example, the taxonomy of ''Phyllotillon'' has been regarded as controversial because of the scarcity of material, and some authors have suggested restricting the genus to the Bugti collections of Pakistan until better fossils are available.<ref name="Li2022" />
The early African chalicotheriine formerly called ''Butleria rusingensis'' has been renamed ''Winamia rusingensis'' because ''Butleria'' was preoccupied.<ref name="Li2022" /> The generic placement of ''"Chalicotherium" pilgrimi'' remains unsettled in the literature, and some African late Neogene material has been referred to ''"Chemositia" tugenensis'' with caution rather than full confidence in the generic assignment.<ref name="CoombsCote2010" /> === Genera ===
{| class="wikitable sortable" ! Genus ! Subfamily ! Representative age ! Main region(s) ! Notes |- | ''Winamia'' | Chalicotheriinae | Early Miocene | East Africa | Replacement name for ''Butleria'', which is preoccupied; usually represented by ''W. rusingensis''.<ref name="Li2022" /> |- | ''Chalicotherium'' | Chalicotheriinae | Late Middle to early Late Miocene | Europe | In recent narrow usage, usually centred on ''C. goldfussi''; several species historically placed here have been reassigned elsewhere.<ref name="Anquetin2007" /><ref name="PalZ2024">{{cite journal |last1=Kampouridis |first1=Panagiotis |title=Disparate occurrences of a chalicotheriine and a schizotheriine chalicothere (Mammalia, Chalicotheriidae) at the Late Miocene hominid locality Hammerschmiede (Germany) |journal=PalZ |year=2024 |doi=10.1007/s12542-024-00685-x}}</ref> |- | ''Kalimantsia'' | Chalicotheriinae | Late Miocene (Turolian) | Balkans (especially Bulgaria) | Based on material from the Kalimantsi area of Bulgaria; a distinct late Miocene Balkan chalicotheriine.<ref name="Geraads2001">{{cite journal |last1=Geraads |first1=Denis |last2=Spassov |first2=Nikolaï |last3=Kovachev |first3=Dimitar |title=New Chalicotheriidae (Perissodactyla, Mammalia) from the Late Miocene of Bulgaria |journal=Journal of Vertebrate Paleontology |year=2001 |volume=21 |issue=3 |pages=596–606 |doi=10.1671/0272-4634(2001)021[0596:NCPMFT]2.0.CO;2}}</ref><ref name="Kampouridis2023" /> |- | ''Anisodon'' | Chalicotheriinae | Middle to Late Miocene | Europe and the Balkans | Re-established as distinct from ''Chalicotherium'' in modern treatments; includes the Sansan species and some southeastern European material.<ref name="Anquetin2007" /><ref name="CoombsGoehlich2019">{{cite journal |last1=Coombs |first1=Margery C. |last2=Göhlich |first2=Ursula B. |title=Anisodon (Perissodactyla, Chalicotheriinae) from the middle Miocene locality Gračanica (Bugojno Basin, Gornji Vakuf, Bosnia and Herzegovina) |journal=Palaeobiodiversity and Palaeoenvironments |year=2019 |doi=10.1007/s12549-018-0357-9}}</ref><ref name="Fahlke2013">{{cite journal |last1=Fahlke |first1=Julia M. |last2=Coombs |first2=Margery C. |last3=Semprebon |first3=Gina M. |title=Anisodon sp. (Mammalia, Perissodactyla, Chalicotheriidae) from the Turolian of Dorn-Dürkheim 1 (Rheinhessen, Germany): morphology, phylogeny, and palaeoecology of the latest chalicothere in Central Europe |journal=Palaeobiodiversity and Palaeoenvironments |year=2013 |volume=93 |pages=151–170 |doi=10.1007/s12549-013-0119-7}}</ref> |- | ''Nestoritherium'' | Chalicotheriinae | Late Miocene to Early Pleistocene | Asia | Revalidated by Chen et al. (2012); includes Chinese late Miocene material and species formerly referred to ''Chalicotherium''.<ref name="Chen2012" /><ref name="XueCoombs1985">{{cite journal |last1=Xue |first1=Xiang-Xu |last2=Coombs |first2=Margery C. |title=A new species of Chalicotherium from the Upper Miocene of Gansu Province, China |journal=Journal of Vertebrate Paleontology |year=1985 |volume=5 |issue=4 |pages=336–344 |doi=10.1080/02724634.1985.10011870}}</ref> |- | ''Hesperotherium'' | Chalicotheriinae | Early to Middle Pleistocene | China | Erected for the last known Chinese chalicotheres; Chen et al. (2012) suggested it may be nested within ''Nestoritherium''.<ref name="Qiu2002">{{cite journal |last1=Qiu |first1=Zhan-Xiang |title=Hesperotherium—A new genus of the last chalicotheres |journal=Vertebrata PalAsiatica |year=2002 |volume=40 |issue=4 |pages=317–325}}</ref><ref name="Chen2012" /> |- | ''Schizotherium'' | Schizotheriinae | Oligocene | Eurasia | Generally treated as the most primitive schizotheriine; best known from Oligocene Eurasian material.<ref name="Li2022" /> |- | ''Borissiakia'' | Schizotheriinae | Late Oligocene to Early Miocene | Asia | Best known from Kazakhstan; some early Miocene Chinese material has been compared with or referred to this genus.<ref name="Li2022" /> |- | ''Phyllotillon'' | Schizotheriinae | Early Miocene | Pakistan; possibly Europe | Taxonomically controversial; some authors restrict the genus to the Bugti material until better fossils are available.<ref name="Li2022" /> |- | ''Moropus'' | Schizotheriinae | Miocene | Mainly North America; also reported from Eurasia | The best-known North American schizotheriine; Li et al. (2022) note a primarily North American distribution but possible early Miocene Eurasian occurrences.<ref name="Li2022" /> |- | ''Metaschizotherium'' | Schizotheriinae | Early to Middle Miocene | Europe | A European schizotheriine; the status of some referred species remains under discussion.<ref name="Li2022" /> |- | ''Tylocephalonyx'' | Schizotheriinae | Miocene | North America | North American dome-skulled schizotheriine.<ref name="Li2022" /> |- | ''Ancylotherium'' | Schizotheriinae | Late Miocene to Pleistocene | Old World | The latest surviving schizotheriine; common in late Miocene Eastern Mediterranean faunas and persisting later in the Old World.<ref name="Li2022" /><ref name="Kampouridis2023" /> |}
== Evolution, biogeography and fossil record == The superfamily Chalicotherioidea first appeared in the Eocene in Asia, with the earliest chalicotheriids proper appearing during the following Oligocene.<ref name=":6">{{Cite book |last1=Cote|first1=Susanne|url=https://www.press.jhu.edu/books/title/11911/foot-himalayas|title=At the Foot of the Himalayas: Paleontology and Ecosystem Dynamics of the Siwalik Record|last2=Coombs|first2=Margery c.|date=2025|publisher=Johns Hopkins University Press|isbn=978-1-4214-5027-8|editor-last=Badgley|editor-first=Catherine|pages=|language=en|chapter=Siwalik Chalicotheriidae|editor-last2=Morgan|editor-first2=Michèle E.|editor-last3=Pilbeam|editor-first3=David}}</ref> By the late Oligocene, they had divided into schizotheriines and chalicotheriines.<ref name="COOMBS-2013" /> Chalicotheriids had a broad Old World distribution Asia, Europe, Africa and North American distribution.<ref name="CoombsCote2010">{{cite book |last1=Coombs |first1=Margery C. |last2=Cote |first2=Susanne M. |chapter=Chalicotheriidae |title=Cenozoic Mammals of Africa |year=2010 |pages=659–668}}</ref> The family reached its greatest diversity in the Miocene.<ref name="CoombsCote2010" />
Asia appears to have been the principal centre of diversification for the family.<ref name="CoombsCote2010" /> Early and middle Neogene records from China, Kazakhstan and surrounding regions show that both chalicotheriines and schizotheriines were well established there, and Asian records continue into the latest history of the group.<ref name="Li2022">{{cite journal |last1=Li |first1=Zhaoyu |last2=Mörs |first2=Thomas |last3=Zhang |first3=Yunxiang |last4=Xie |first4=Kun |last5=Li |first5=Yongxiang |title=New Material of Schizotheriine Chalicothere (Perissodactyla, Chalicotheriidae) from the Xianshuihe Formation (Early Miocene) of Lanzhou Basin, Northwest China |journal=Journal of Mammalian Evolution |year=2022 |volume=29 |pages=877–889 |doi=10.1007/s10914-022-09619-3}}</ref> The early Miocene Lanzhou Basin fauna, for example, preserves a schizotheriine close to ''Borissiakia'', while later Asian assemblages include advanced chalicotheriines such as ''Nestoritherium'' and ''Hesperotherium''.<ref name="Li2022" />
Europe preserves a particularly important Miocene record of the family, including classic middle Miocene localities such as Sansan and a long later Neogene history in Central and southeastern Europe.<ref name="Kampouridis2024">{{cite journal |last1=Kampouridis |first1=Panagiotis |title=Disparate occurrences of a chalicotheriine and a schizotheriine chalicothere (Mammalia, Chalicotheriidae) at the Late Miocene hominid locality Hammerschmiede (Germany) |journal=PalZ |year=2024 |volume=98 |pages=313–329 |doi=10.1007/s12542-024-00685-x}}</ref> Schizotheriines were widespread in Europe during the middle Miocene, especially in the genus ''Metaschizotherium'', whereas chalicotheriines such as ''Anisodon'' and later Balkan forms such as ''Kalimantsia'' are characteristic elements of later Miocene faunas.<ref name="Kampouridis2024" /><ref name="Kampouridis2023">{{cite journal |last1=Kampouridis |first1=Panagiotis |last2=Rățoi |first2=Bogdan Gabriel |last3=Ursachi |first3=Laurențiu |title=New evidence for the unique coexistence of two subfamilies of clawed perissodactyls (Mammalia, Chalicotheriidae) in the Upper Miocene of Romania and the Eastern Mediterranean |journal=Journal of Mammalian Evolution |year=2023 |volume=30 |pages=641–656 |doi=10.1007/s10914-023-09657-5}}</ref> Late Miocene localities in Romania and the Eastern Mediterranean are especially important because they document coexistence of the two subfamilies in the same broad region.<ref name="Kampouridis2023" />
African chalicotheriids are less diverse in the published record than those of Eurasia, but the continent preserves both early and late members of the family.<ref name="CoombsCote2010" /> Coombs and Cote noted early Miocene African chalicotheriines and later Neogene material assigned with varying degrees of confidence to chalicotheriines and schizotheriines, showing that Africa remained part of the family's range after the European record declined.<ref name="CoombsCote2010" /> North American records, by contrast, are dominated by schizotheriines, especially ''Moropus'' and ''Tylocephalonyx'', and indicate that the family dispersed successfully into the continent even though the chalicotheriine branch is not a characteristic part of the North American record.<ref name="CoombsCote2010" /> A Panamanian record also shows that small-bodied schizotheriines reached Central America during the early Miocene.<ref name="WoodRidgwell2015">{{cite journal |last1=Wood |first1=Aaron R. |last2=Ridgwell |first2=Nicole M. |title=The first Central American chalicothere (Mammalia, Perissodactyla) and the paleobiogeographic implications for small-bodied schizotheriines |journal=Journal of Vertebrate Paleontology |year=2015 |volume=35 |issue=3 |article-number=e923893 |doi=10.1080/02724634.2014.923893}}</ref>
The palaeobiogeographic history of the family also shows that the two subfamilies did not always share the same distribution or ecological settings.<ref name="Kampouridis2023" /><ref name="Kampouridis2024" /> Recent work has emphasised that confirmed coexistence of chalicotheriines and schizotheriines in the same localities is relatively uncommon, especially after the late Miocene, though members of the two families still occasionally co-existed even towards the end of their existence in the Early Pleistocene.<ref name="Kampouridis2023" />
Never common animals in the fossil record, the chalicotheres declined from the late Neogene onwards, disappearing from North America and Europe by end of the Miocene.<ref>{{Cite journal |last1=Wood |first1=Aaron R. |last2=Ridgwell |first2=Nicole M. |date=2015-05-04 |title=The first Central American chalicothere (Mammalia, Perissodactyla) and the paleobiogeographic implications for small-bodied schizotheriines |url=http://www.tandfonline.com/doi/full/10.1080/02724634.2014.923893 |journal=Journal of Vertebrate Paleontology |language=en |volume=35 |issue=3 |article-number=e923893 |doi=10.1080/02724634.2014.923893 |bibcode=2015JVPal..35E3893W |issn=0272-4634}}</ref><ref name="Kampouridis-2024">{{Cite journal |last1=Kampouridis |first1=Panagiotis |last2=Hartung |first2=Josephina |last3=Lechner |first3=Thomas S. |last4=Kargopoulos |first4=Nikolaos |last5=Böhme |first5=Madelaine |date=June 2024 |title=Disparate occurrences of a chalicotheriine and a schizotheriine chalicothere (Mammalia, Chalicotheriidae) at the Late Miocene hominid locality Hammerschmiede (Germany) |url=https://link.springer.com/10.1007/s12542-024-00685-x |journal=PalZ |language=en |volume=98 |issue=2 |pages=313–329 |doi=10.1007/s12542-024-00685-x |bibcode=2024PalZ...98..313K |issn=0031-0220|doi-access=free }}</ref> The youngest chalicotheres are the chalicotheriines ''Hesperotherium'' from the Early Pleistocene of China,<ref>{{Cite journal |last=Tong |first=HaoWen |date=September 2007 |title=Occurrences of warm-adapted mammals in north China over the Quaternary Period and their paleo-environmental significance |url=http://link.springer.com/10.1007/s11430-007-0096-7 |journal=Science in China Series D: Earth Sciences |language=en |volume=50 |issue=9 |pages=1327–1340 |doi=10.1007/s11430-007-0096-7 |bibcode=2007ScChD..50.1327T |issn=1006-9313|url-access=subscription }}</ref> ''Nestoritherium'' from the Early Pleistocene of Myanmar,<ref>T. Tsubamoto, Zin-Maung-Maung-Thein, Thaung-Htike, N. Egi, Chit-Sein, Maung-Maung, M. Takai Discovery of chalicothere and ''Dorcabune'' from the upper part (lower Pleistocene) of the Irrawaddy Formation, Myanmar Asian Paleoprimatology, 4 (2006), pp. 137–142</ref> as well as the schizotheriine ''Ancylotherium'' from the Early Pleistocene of Eastern and Southern Africa,<ref>{{Cite journal |last1=Handa |first1=Naoto |last2=Nakatsukasa |first2=Masato |last3=Kunimatsu |first3=Yutaka |last4=Tsubamoto |first4=Takehisa |last5=Nakaya |first5=Hideo |date=2021-12-02 |title=The Chalicotheriidae (Mammalia, Perissodactyla) from the upper Miocene Nakali Formation, Kenya |url=https://www.tandfonline.com/doi/full/10.1080/08912963.2021.1876042 |journal=Historical Biology |language=en |volume=33 |issue=12 |pages=3522–3529 |doi=10.1080/08912963.2021.1876042 |bibcode=2021HBio...33.3522H |issn=0891-2963|url-access=subscription }}</ref> also possibly known from the Early Pleistocene of China.<ref>{{Cite journal |last1=Chen |first1=Shao-kun |last2=Deng |first2=Tao |last3=Pang |first3=Li-bo |last4=He |first4=Wen |last5=Chen |first5=Shan-qin |date=November 2012 |title=A juvenile skull of Ancylotherium (Mammalia, Perissodactyla, Chalicotheriidae) from the Pliocene of China |url=https://linkinghub.elsevier.com/retrieve/pii/S0016699512000848 |journal=Geobios |language=en |volume=45 |issue=6 |pages=527–534 |doi=10.1016/j.geobios.2012.06.002|bibcode=2012Geobi..45..527C |url-access=subscription }}</ref> In China, ''Hesperotherium'' is suggested to have survived until near the end of the Early Pleistocene, around 1 million years ago.<ref>{{Cite journal |last=Hu |first=Haiqian |last2=Tong |first2=Haowen |last3=Han |first3=Fei |last4=Dai |first4=Hui |last5=Huang |first5=Wanbo |last6=Jiangzuo |first6=Qigao |last7=Rummy |first7=Paul |last8=Wang |first8=Xunqian |last9=Lin |first9=Yu |last10=Wei |first10=Guangbiao |date=March 2025 |title=Chronological and palaeoecological insights into the Dayakou fauna in Yanjinggou, Chongqing, China: Responses of large mammals to the Early-Middle Pleistocene Climate Transition |url=https://linkinghub.elsevier.com/retrieve/pii/S0277379125000198 |journal=Quaternary Science Reviews |language=en |volume=352 |article-number=109199 |doi=10.1016/j.quascirev.2025.109199}}</ref><ref>{{Cite journal |last=Shaokun |first=Chen |last2=Libo |first2=Pang |last3=Xin |first3=Hu |last4=Guangbiao |first4=Wei |last5=Yun |first5=Chen |last6=Runqing |first6=Ge |date=2017-01-30 |title=New remains of Hesperotherium(Chalicotheriidae, Perissodactyla) from Yanjinggou, Wanzhou District, Chongqing |url=http://www.dsjyj.com.cn//en/article/doi/10.11928/j.issn.1001-7410.2017.01.15 |journal=Quaternary Sciences |language=zh |volume=37 |issue=1 |pages=166–173 |doi=10.11928/j.issn.1001-7410.2017.01.15 |issn=1001-7410}}</ref>
==References== {{Reflist|refs= <ref name="Gill, 1872">{{cite book|last1=Gill|first1=Theodore|title=Arrangement of the Families of Mammals|date=1872|publisher=Smithsonian|location=Washington|pages=8, 71, 76|url=https://biodiversitylibrary.org/page/1336697|series=Smithsonian Miscellaneous Collections|volume=230}}</ref> }}
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Category:Chalicotheres Category:Prehistoric mammal families Category:Piacenzian extinctions Category:Clawed herbivores Category:Eocene first appearances Category:Taxa named by Theodore Gill