Litopterna
Temporal range: Paleocene–Holocene
Skeleton of Macrauchenia (Macraucheniidae)
Skeleton of Diadiaphorus (Proterotheriidae)
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Clade: Panperissodactyla
Order: †Litopterna
Ameghino 1889
Subgroups

Litopterna (from Ancient Greek: λῑτή πτέρνα "smooth heel") is an extinct order of South American native ungulates that lived from the Paleocene to the end of the Pleistocene-early Holocene around 63 million-12,000 years ago, and were also present in Antarctica during the Eocene. They represent the second most diverse group of South American ungulates after Notoungulata.[1] It is divided into nine families, with Proterotheriidae and Macraucheniidae being the most diverse and last surviving families.[2]

Diversity

Skeleton of Theosodon (Macraucheniidae)
Historic life restoration of Thoatherium (Proterotheriidae)

The body forms of many litopterns, notably in the limb and skull structure, are broadly similar to those of living ungulates, unlike other South American native ungulate groups, which are often strongly divergent from living ungulates.[3] Paleocene and Eocene litopterns generally had small body masses, with Protolipterna (Protolipternidae) estimated to have had a body mass of 0.5–1.5 kilograms (1.1–3.3 lb), though the Eocene sparnotheriodontids were considerably larger, with estimated body masses of around 400 kilograms (880 lb). Most proterotheriids had body masses of around 15 to 80 kilograms (33 to 176 lb) while many macraucheniids had body masses of around 80–120 kilograms (180–260 lb). Some of the last macraucheniids like Macrauchenia were considerably larger, with body masses around a ton.[1] Adianthidae generally had small body masses, with members of the genus Adianthus estimated to weigh 7.4–20 kilograms (16–44 lb). Members of the proterotheriid subfamily Megadolodinae are noted for having bunodont (rounded cusp) molar teeth, which is largely unique to litopterns among South American native ungulates.[2][1] Litopterns of the mid-late Cenozoic had hinge-like limb joints and hooves similar to those of modern ungulates, with the weight being supported on three toes in macraucheniids and one in proterotheriids, with the protherotheriid Thoatherium developing greater toe reduction than that present in living horses.[1] Macraucheniids had long necks and limbs.[4] Members of the macraucheniid subfamily Macraucheniinae saw the progressive migration of the nasal opening to the top of the skull,[5] which was often historically suggested to indicate the presence of a trunk, though other authors have suggested that a moose-like prehensile lip is more likely.[6]

Ecology

Litopterns were likely hindgut fermenters.[3] At least some macraucheniids like Macrauchenia are suggested to have been mixed feeders feeding on both browse and grass.[7] Sparnotheriodontids are suggested to have been browsers.[8] Some proterotheriids are suggested to have been browsers,[9] while some members proterotheriid subfamily Megadolodinae like Megadolodus have been suggested to have been omnivorous with at least part of their diet consisting of hard fruit.[2]

Evolutionary history

Litopterna, like other "South American native ungulates" is thought to have originated from groups of archaic "condylarths" that migrated from North America.[1] Sequencing of the collagen proteome and mitochondrial genome of Macrauchenia has revealed that litopterns are true ungulates, sharing a common ancestor with Notoungulata, and with their closest living relatives being Perissodactyla (the group containing living equines, rhinoceros and tapirs) as part of the clade Panperissodactyla, with the split from Perissodactyla being estimated at around 66 million years ago.[10][11] The relationship of Litopterna to other South American native ungulate groups is uncertain, though it may be closely related to the "condylarth" group Didolodontidae. The earliest litopterns appeared during the early Paleocene, around 63 million years ago.[1]

Aside from South America, sparnotheriodontids are also known from the Eocene aged La Meseta Formation in the Antarctic Peninsula, representing the only record of litopterns on the Antarctic continent. Litopterns declined during the Pliocene and Pleistocene, likely as a result climatic change and competition with recently immigrated North American ungulates who arrived as part of the Great American interchange, following the connection of the previously isolated North and South America via the Isthmus of Panama.[1] Macrauchenia, Macraucheniopsis, Xenorhinotherium (Macraucheniidae) and Neolicaphrium (Protherotheriidae) were the last surviving genera of litopterns. All four became extinct at the end of the Late Pleistocene around 12,000 years ago as part of the Quaternary extinction event, along with most other large mammals in the Americas, co-inciding with the arrival of the first humans to the continent. It is possible that hunting had a causal role in their extinction.[12][13][14][1]

Classification

This section relies largely or entirely on a single source. Relevant discussion may be found on the talk page. Please help improve this article by introducing citations to additional sources.Find sources: "Litopterna" – news · newspapers · books · scholar · JSTOR (April 2022)

References

  1. ^ a b c d e f g h Croft, Darin A.; Gelfo, Javier N.; López, Guillermo M. (2020-05-30). "Splendid Innovation: The Extinct South American Native Ungulates". Annual Review of Earth and Planetary Sciences. 48 (1): 259–290. Bibcode:2020AREPS..48..259C. doi:10.1146/annurev-earth-072619-060126. ISSN 0084-6597. S2CID 213737574.
  2. ^ a b c Carrillo, Juan D.; Suarez, Catalina; Benites-Palomino, Aldo Marcelo; Vanegas, Andrés; Link, Andrés; Rincón, Aldo F.; Luque, Javier; Cooke, Siobhán B.; Tallman, Melissa; Billet, Guillaume (2023-08-31). "New remains of Neotropical bunodont litopterns and the systematics of Megadolodinae (Mammalia: Litopterna)". Geodiversitas. 45 (15). doi:10.5252/geodiversitas2023v45a15. ISSN 1280-9659. S2CID 261638835.
  3. ^ a b Croft, Darin A.; Lorente, Malena (2021-08-17). Smith, Thierry (ed.). "No evidence for parallel evolution of cursorial limb adaptations among Neogene South American native ungulates (SANUs)". PLOS ONE. 16 (8): e0256371. doi:10.1371/journal.pone.0256371. ISSN 1932-6203. PMC 8370646. PMID 34403434.
  4. ^ Schmidt, Gabriela I.; Ferrero, Brenda S. (2014-07-29). "Taxonomic reinterpretation of Theosodon hystatus Cabrera and Kraglievich, 1931 (Litopterna, Macraucheniidae ) and phylogenetic relationships of the family". Journal of Vertebrate Paleontology. 34 (5): 1231–1238. Bibcode:2014JVPal..34.1231S. doi:10.1080/02724634.2014.837393. hdl:11336/18953. ISSN 0272-4634. S2CID 86091386.
  5. ^ Forasiepi, Analía M.; MacPhee, Ross D. E.; Del Pino, Santiago Hernández; Schmidt, Gabriela I.; Amson, Eli; Grohé, Camille (2016-06-22). "Exceptional Skull of Huayqueriana (Mammalia, Litopterna, Macraucheniidae) From the Late Miocene of Argentina: Anatomy, Systematics, and Paleobiological Implications". Bulletin of the American Museum of Natural History. 404: 1–76. doi:10.1206/0003-0090-404.1.1. ISSN 0003-0090. S2CID 89219979.
  6. ^ Moyano, Silvana Rocio; Giannini, Norberto Pedro (November 2018). "Cranial characters associated with the proboscis postnatal-development in Tapirus (Perissodactyla: Tapiridae) and comparisons with other extant and fossil hoofed mammals". Zoologischer Anzeiger. 277: 143–147. doi:10.1016/j.jcz.2018.08.005. S2CID 92143497.
  7. ^ de Oliveira, Karoliny; Asevedo, Lidiane; Calegari, Marcia R.; Gelfo, Javier N.; Mothé, Dimila; Avilla, Leonardo (August 2021). "From oral pathology to feeding ecology: The first dental calculus paleodiet study of a South American native megamammal". Journal of South American Earth Sciences. 109: 103281. Bibcode:2021JSAES.10903281D. doi:10.1016/j.jsames.2021.103281. S2CID 233678648.
  8. ^ Bond, M.; Reguero, M. A.; Vizcaíno, S. F.; Marenssi, S. A. (January 2006). "A new 'South American ungulate' (Mammalia: Litopterna) from the Eocene of the Antarctic Peninsula". Geological Society, London, Special Publications. 258 (1): 163–176. doi:10.1144/GSL.SP.2006.258.01.12. ISSN 0305-8719.
  9. ^ Morosi, Elizabeth; Ubilla, Martin (2019-02-07). "Dietary and palaeoenvironmental inferences in Neolicaphrium recens Frenguelli, 1921 (Litopterna, Proterotheriidae) using carbon and oxygen stable isotopes (Late Pleistocene; Uruguay)". Historical Biology. 31 (2): 196–202. doi:10.1080/08912963.2017.1355914. ISSN 0891-2963. S2CID 133673644.
  10. ^ Welker, Frido; Collins, Matthew J.; Thomas, Jessica A.; Wadsley, Marc; Brace, Selina; Cappellini, Enrico; Turvey, Samuel T.; Reguero, Marcelo; Gelfo, Javier N. (March 18, 2015). "Ancient proteins resolve the evolutionary history of Darwin/'s South American ungulates". Nature. 522 (7554): 81–84. Bibcode:2015Natur.522...81W. doi:10.1038/nature14249. hdl:11336/14769. ISSN 1476-4687. PMID 25799987. S2CID 4467386.
  11. ^ Westbury, Michael; Baleka, Sina; Barlow, Axel; Hartmann, Stefanie; Paijmans, Johanna L.A.; Kramarz, Alejandro; Forasiepi, Analía M; Bond, Mariano; Gelfo, Javier N.; Reguero, Marcelo A.; López-Mendoza, Patricio; Taglioretti, Matias; Scaglia, Fernando; Rinderknecht, Andrés; Jones, Washington (2017-06-27). "A mitogenomic timetree for Darwin's enigmatic South American mammal Macrauchenia patachonica". Nature Communications. 8 (1): 15951. Bibcode:2017NatCo...815951W. doi:10.1038/ncomms15951. ISSN 2041-1723. PMC 5490259. PMID 28654082.
  12. ^ Webb, S. D. (1976). "Mammalian Faunal Dynamics of the Great American Interchange". Paleobiology. 2 (3): 220–234. Bibcode:1976Pbio....2..220W. doi:10.1017/S0094837300004802. JSTOR 2400220. S2CID 251050063.
  13. ^ Marshall, L. G.; Cifelli, R. L. (1990). "Analysis of changing diversity patterns in Cenozoic land mammal age faunas, South America". Palaeovertebrata. 19: 169–210. Retrieved 2018-10-08.
  14. ^ Webb, S. D. (1991). "Ecogeography and the Great American Interchange". Paleobiology. 17 (3): 266–280. Bibcode:1991Pbio...17..266W. doi:10.1017/S0094837300010605. JSTOR 2400869. S2CID 88305955.
  15. ^ "PBDB". paleobiodb.org. Retrieved 2022-04-29.

Further reading

External links

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Genera of South American native ungulates
Taxon identifiers
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