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Titolo:
Specialized knee joints in some extinct, endemic, South American herbivores
Autore:
Shockey, BJ;
Indirizzi:
New Jersey City Univ, Dept Biol, Jersey City, NJ 07305 USA New Jersey CityUniv Jersey City NJ USA 07305 , Jersey City, NJ 07305 USA
Titolo Testata:
ACTA PALAEONTOLOGICA POLONICA
fascicolo: 2, volume: 46, anno: 2001,
pagine: 277 - 288
SICI:
0567-7920(200106)46:2<277:SKJISE>2.0.ZU;2-G
Fonte:
ISI
Lingua:
ENG
Soggetto:
FUNCTIONAL-MORPHOLOGY; NICHE DIFFERENTIATION; LATE OLIGOCENE; BOLIVIA; EVOLUTIONARY; EQUIDAE; ECOLOGY; HORSES; SALLA;
Keywords:
herbivores; Notoungulata; Litopterna; Glyptodontoidea; knee; passive stay;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
27
Recensione:
Indirizzi per estratti:
Indirizzo: Shockey, BJ New Jersey City Univ, Dept Biol, 2039 Kennedy Blvd, Jersey City, NJ 07305 USA New Jersey City Univ 2039 Kennedy Blvd Jersey City NJ USA 07305
Citazione:
B.J. Shockey, "Specialized knee joints in some extinct, endemic, South American herbivores", ACT PAL POL, 46(2), 2001, pp. 277-288

Abstract

Distal femora of some extinct, endemic, South American herbivores are shown to have modifications related to knee extension. Toxodon (Order Notoungulata) had an enlarged medial trochlear ridge (MTR) similar to those seen in horses. The MTR of horses serves to 'lock' the patella and ligaments in theproximal position and it likely function the same for Toxodon. The patellaof Toxodon has a medial process that would have locked by wrapping around the MTR. Macraucheniid and proterotheriid litopterns may also have had kneelocks, but with a different mechanism. The femora of these litopterns havedeep suprapatellar fossae in which the patellae could have become lodged. Indeed, the distal end of the patella of cf. Eoauchenia (Proterotheriidae) conforms to and is supported within the suprapatellar fossa. Several glyptodontids (Order Xenarthra) have conical MTRs that would have impeded the medial patellar ligaments during the initiation of extension. This would have caused patellar rotation and resulted in a complex knee extension. These glyptodonts also had suprapatellar fossae, suggesting that the ligaments slidover the MTR and 'locked' during hyperextension. Locking knees in these diverse animals implies that they stood for long periods of time and did not engage in intermittent, 'bout feeding as seen in modern ruminants.

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Documento generato il 19/01/20 alle ore 00:32:18