status = Fossil

image_width = 250px
image_caption = "Macrauchenia"
name = Litopterna
regnum = Animalia
phylum = Chordata
classis = Mammalia
infraclassis = Eutheria
superordo = †Meridiungulata
ordo = †Litopterna
ordo_authority = Ameghino, 1889
The Litopterna ("Simple Ankles") is an order of fossil hoofed mammals (ungulates) from the Tertiary period that displays toe reduction. Three-toed, and even a one-toed horselike form were developed.

This order, known only from South America, was common and varied in early faunas and persisted, in decreasing variety, into the Pleistocene. Early forms are near the condylarths, to such an extent that the litopterns might be considered merely as surviving and diversely specialized condylarths. They are suspected of being descended from South American condylarths, and therefore to have the same source as the latter. However, there is a growing number of scientists who believes the Litopterna (together with other South-American ungulates) originated completely independent from the other ungulates, thus are unrelated to the condylarths. They proposed a new clade to contain these groups: the Meridiungulata. "Macrauchenia" was the youngest genus of litopterns, and was the only litoptern group to survive the Great American Interchange; it died out during the Pleistocene.

The Litopterna, like the notoungulates and pyrotheres, are examples of ungulate mammals that arose relatively independently in "splendid isolation" on the island continent of South America. Like Australia, South America was isolated from all other continents following the breakup of Gondwana. During this period of isolation, unique mammals evolved to fill ecological niches similar to other mammals elsewhere. The Litopterna occupied ecological roles as browsers and grazers similar to horses and camels in Laurasia.

Families of Litopterns

*Order Litopterna - Litopterans (all members of the order extinct South American forms)
**Family Protolipternidae - "incertae sedis"
**Superfamily Macrauchenioidea
***Family Macraucheniidae
***Family Notonychopidae
***Family Adianthidae
**Superfamily Proterotherrioidea
***Family Proterotheriidae

Proposed ancestry

This tree shows a proposed ancestry of several mammals including the Litopterna:


*McKenna, M. C, and S. K. Bell. 1997. Classification of Mammals Above the Species Level. Columbia University Press, New York, 631 pp.

External links

* [ artist's rendition] of a Macrauchenia, a representative genus of the Litopterna. Retrieved from the Red Académica Uruguaya [ megafauna page] .

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Look at other dictionaries:

  • Litopterna — Macrauchenia Zeitraum Eozän bis Pleistozän 55 bis 0,01 Mio. Jahre Fundorte Südamerika Antarktis …   Deutsch Wikipedia

  • Litopterna —   Litopterna Escala temporal: Eoceno Pleistoceno …   Wikipedia Español

  • Litopterna — Macrauchenia sp …   Wikipédia en Français

  • litopterna — li·top·ter·na …   English syllables

  • litopterna — ˌ ̷ ̷(ˌ) ̷ ̷ˈtərnə noun plural Usage: capitalized Etymology: New Latin, from Greek litos plain, smooth + pterna heel : an order of extinct So. American Cenozoic ungulates with one or three functional toes …   Useful english dictionary

  • Notonychopidae —   Notonychopidae …   Wikipedia Español

  • Litopterne — Litopterna …   Wikipédia en Français

  • Macrauchenia — Zeichnerische Lebendrekonstruktion von Macrauchenia Zeitraum Miozän bis Pleistozän 9 Mio. Jahre bis 11.000 Jahre Fundorte …   Deutsch Wikipedia

  • Meridiungulata — Südamerikanische Huftiere Macrauchenia Zeitraum Paläozän bis Pleistozän 60 bis 1 Mio. Jahre Fossilfundorte Südamerika …   Deutsch Wikipedia

  • Südhuftiere — Südamerikanische Huftiere Macrauchenia Zeitraum Paläozän bis Pleistozän 60 bis 1 Mio. Jahre Fossilfundorte Südamerika …   Deutsch Wikipedia

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