Paleobiology of Santacrucian native ungulates (Meridiungulata: Astrapotheria, Litopterna, and Notoungulata)

CASSINI, G.H.; CERDEÑO, E; VILLAFAÑE, A.L.; MUÑOZ, N.A.

Early Miocene paleobiology in Patagonia: High-latitude paleocommunities of the Santa Cruz Formation

Cambridge University Press

Lugar: Cambridge; Año: 2012; p. 243 - 286

A paleobiological study of Santacrucian native ungulates ispresented in this chapter. Seven families are recorded:Hegetotheriidae, Interatheriidae, Toxodontidae, and Homalodotheriidae(Notoungulata); Proterotheriidae andMacraucheniidae (Litopterna); and Astrapotheriidae(Astrapotheria); however, a detailed systematic revision isstill pending. A broad body size range is recorded.Typotheres (Hegetotheriidae þ Interatheriidae) vary from2 to 10 kg, proterotheriids vary from20 to 100 kg, toxodontsand macraucheniids surpass 100 kg, and astrapotheres reach1000 kg. The highest taxonomic richness corresponds to therange between 20 and 100 kg. Locomotor behavior is interpretedas mostly cursorial. Typotheres might have engagedin occasional digging, but this group also includes the mostagile and fastest forms, more so than proterotheriids. Onlytwo taxa in the sample (Interatherium and Astrapotherium)show evidence of swimming capabilities and potentialaquatic habits. In contrast, feeding behavior presents lessvariation, which agrees with previous interpretations:notoungulates inhabited open habitats and fed mainly ongrass, while litopterns and astrapotheres inhabited closedhabitats and were mainly browsers. We infer that notoungulateshad exceptional chemical digestion capabilitieswhereas litopterns may have relied on long periods ofchewing to process their food.