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Pleistocene, , Chile central, Stable isotopes
Abstract:
Limited pollen and limnogeological evidence show that central Chile (31°S–36° S) had a more temperate climate during the Late Pleistocene. Questions remain, however, regarding the extent of the mediterranean sclerophyllous forest currently found in this region and its postglacial dynamics. The extinct Notiomastodon platensis was the only proboscidean species that inhabited central Chile and ranged across a broad latitudinal range (31°S–42°S) during the Pleistocene. Although this species was a mixed-feeder, we reconstructed past ecosystems when these animals were alive using stable isotope evidence from dental root collagen (δ13C and δ15N) of N. platensis specimens collected from present-day semi-arid and mediterranean ecosystems in central Chile (31°S–36°S). Compared to modern vegetation isotope baselines, we expected the isotopic value of the Estimated Consumed Diet (ECD) (the probable diet of N. platensis) to be similar to the isotopic signal (low values) from vegetation adapted to temperate rainforests. However, elevated δ15NECD values indicate a paleo-vegetation more similar to a xerophyte scrub influenced by a semi-arid paleoclimate. δ13CECD values reflect a wooded/forested environment but adapted to more arid conditions. Although high δ15N values could be influenced by other non-climatic factors (e.g., grazing effect), our combined evidence suggests that these gomphotheres roamed through ecosystem very similar to those found today in central Chile. Our results show the need for multiproxy reconstructions of past environmental change in Mediterranean regions where the abundance of entomophilous species can lead to biased pollen reconstructions.
