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Megaterídeos (Mammalia, Xenarthra) do Quaternário de Caçapava do Sul, Rio Grande do Sul, com considerações sobre a flora associada

2002; Volume: 27; Linguagem: Inglês

ISSN

2357-3767

Autores

Édison Vicente Oliveira, Tânia Lindner Dutra, Flora Zeltzer,

Tópico(s)

Fish biology, ecology, and behavior

Resumo

Are identified Megatherium americanum and Eremotherium laurillardi for the Passo do Megaterio locality, in the Arroio Pessegueiro, Cacapava do SuI. The deposit is characterized by conglomerate sandstones, sandy siltstones and pelites, and the mammals are from the base of finning upward in the lower part of the profile. For the identification of Megatherium is suggested the exclusion of ambiguous characters such as relatively deep mandibular body, and transversely expanded proximally and distally, and that these genera could be distinguished, between other elements, on the basis of unique character combinations from femur and mandible. Derived characters in Megatherium are (1) symphysis extending to distal margin of m2; (2) depth of dentary, from alveolar margin of m3 to lowest point of ventral margin, higher than 195 mm; (3) medial femoral border prominently convex and, (4) patellar trochlea not medially extended. Derived characters in Eremotherium are: (1) symphysis extending to m1 or between m1 and m2; (2) depth of dentary, from alveolar margin of m3 to lowest point of ventral margin, lesser than 195 mm; (3) medial femoral border nearly rectilinear and, (4) patellar trochlea medially extended approxi- mately until to the level of the medial margin of the internal tibial condyle. It is possible that some species from south South America such as Megatherium medinae and Megatherium lundi (or M seijoi) could belong to Eremotherium rather than Megatherium. The presence of Megatherium americanum suggests a medial Pleistocene (Bonaerian) age for the Rio Grande do Sul site. Thus, caution must be held in the use of Eremotherium laurillardi as representing latest Pleistocene times, mainly as support to biogeographic inferences.

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