Proterotheriidae

Proterotheriidae Temporal range: Eocene–Late Pleistocene PreꞒ Ꞓ O S D C P T J K Pg N
Skeleton of Thoatherium
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	†Litopterna
Suborder:	† Lopholipterna
Superfamily:	†Proterotherioidea
Family:	†Proterotheriidae Ameghino 1887
Synonyms
Anisolambdidae Soria, 2001

Proterotheriidae is an extinct family of litoptern ungulates known from the Eocene-Late Pleistocene of South America. Members of the group were small-medium sized cursorial herbivores with brachydont teeth, with their toes showing progressive reduction, with later members of the group bearing weight on a single large toe similar to living horses.^[1]

Description

Two subfamilies and 18 genera of Proterotheriidae are known. All forms were small or medium-sized. Typical is a reduction of the number of toes and brachydont or mesodont teeth. The family is recorded since the late Palaeocene. Various fossils are known from many parts of the South American continent. The diversity decreased in the Miocene to Pliocene and it has been assumed for a long time that they entirely disappeared in the late Pliocene. However, fossils found in Argentina, Brazil and Uruguay show that one member of the group, Neolicaphrium recens survived into the Late Pleistocene.^[2][3][4]

Better known genera of the family include Diadiaphorus and Thoatherium from the Miocene.^[2]

Taxonomy

• Proterotheriidae^[5][6]
  • Anisolambda
  • Anisolophus
  • Brachytherium
  • Diadiaphorus
  • Diplasiotherium
  • Eoauchenia
  • Eolicaphrium
  • Epecuenia
  • Epitherium
  • Guilielmofloweria
  • Heteroglyphis
  • Lambdaconus
  • Lambdaconops
  • Mesolicaphrium
  • Neobrachytherium
  • Neodolodus
  • Neolicaphrium
  • Olisanophus
  • Paramacrauchenia
  • Paranisolambda
  • Picturotherium
  • Prolicaphrium
  • Promylophis^[7]
  • Proterotherium
  • Protheosodon
  • Pseudobrachytherium^[8]
  • Tetramerorhinus
  • Thoatherium
  • Thoatheriopsis
  • Villarroelia
  • Uruguayodon
  • Wainka
  • Xesmodon
  • Megadolodinae
    • Bounodus
    • Megadolodus
  • Indaleciidae
    • Adiantoides
    • Indalecia

Proterotheriidae is traditionally considered to include two subfamilies, Anisolambdinae and Proterotheriinae. Anisolambdinae (also called Anisolambdidae in some studies) was proposed to unite the primitive and earlier forms

Proterotheriidae was redefined by McGrath and colleagues in 2019 to be all taxa closer to Tetramerorhinus than Macrauchenia, Tricoelodus or Protolipterna.^[5] The cladogram below shows the modified results of their phylogenetic analysis, where incomplete taxa were placed based on morphology. The unrelated genera of the polyphyletic taxon Anisolambdinae or Anisolambdidae is highlighted in pink.^[6]

Proterotheriidae

Megadolodinae Megadolodus Bounodus Indaleciidae Indalecia Adiantoides Paramacrauchenia Anisolambda Lambdaconus suinus Lambdaconus inaequifacies Lambdaconus lacerum Paranisolambda Picturotherium Neodolodus Protheosodon Anisolophus floweri Anisolophus australis Anisolophus minusculus Prolicaphrium Olisanophus Mesolicaphrium Diplasiotherium Villarroelia Tetramerorhinus fleaglei Tetramerorhinus prosistens Tetramerorhinus cingulatum Tetramerorhinus lucarius Tetramerorhinus mixtum Diadiaphorus Thoatherium Brachytherium Thoatheriopsis Proterotherium Neobrachytherium ameghinoi Eoauchenia Neobrachytherium ullumense Neobrachytherium morenoi Neobrachytherium intermedium Neolicaphrium Epitherium Uruguayodon

References

Wikimedia Commons has media related to Proterotheriidae.

1. S2CID 261638835
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   doi:10.4072/rbp.2009.3.06
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3. S2CID 84000052
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4. hdl:11336/56638
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   S2CID 204142828
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   S2CID 216236954
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7. S2CID 256355550
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8. S2CID 219425197
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