Reassesment of the Pliocene-Pleistocene continental time scale of Southern South America. Correlation of the type Chapadmalalan with Bolivian sections

Recently MacFadden et al. (1993) described undiferentiated Montehermosan-Chapadmalalan sections at Inchasi in Bolivia. The supposed failure to correlate more accurately the Inchasi sections with the standard time scale points up the drawbacks of “Land-mammal ages” view as discussed by Cione and Tonni (in press). Ongoing research in the pampean region permits the proposal of a relatively reliable local biostratigraphic scale for the Pliocene-Pleistocene. The previous Montehermosan faunal lists (e.g. Marshall et al., 1983) actually are a mix of Montehermosan and Chapadmalalan taxa. s paper, Montehermosan and Chapadmalalan are confirmed as distinct stages-ages, supported by diagnostic guide fossils. The Inchasi sections are correlated with the Chapadmalalan on the basis of mammal evidence. The magnetostratigraphic studies at Inchasi confirm that at least part of the Chapadmalalan is older than previously supposed. Our studies show that Chapadmalalan rocks appear to be more widespread than previously envisioned.