Late quaternary alluvial stratigraphy of a low-order tributary in central Texas, USA and its response to climate and sediment supply

A paleomegafauna site from central Amazonia with exceptional preservation of mastodons and ground sloths allows for the first time a precise age control based on ¹⁴C analysis, which, together with sedimentological and δ¹³C isotope data, provided the basis to discuss habitat evolution within the context of climate change during the past 15,000 yr. The fossil-bearing deposits, trapped within a depression in the Paleozoic basement, record three episodes of sedimentation formed on floodplains, with an intermediate unit recording a catastrophic deposition through debris flows, probably favored during fast floodings. The integrated approach presented herein supports a change in humidity in central Amazonia through the past 15,000 yr, with a shift from drier to arboreal savanna at 11,340 (±50) ¹⁴C yr B.P. and then to a dense forest like we see today at 4620 (±60) ¹⁴C yr B.P.