stabilizes at this level. In particular, the KM5c interglacial during the Mid-Piacenzian Warm Period occurred during an orbital configuration close to the current situation, with similar geographical distribution of solar insolation. Climate of the Piacenzian would have started as a somewhat wet and warm period in North America occurring just after a brief cooling period of the Zanclean. Deposition of sediments and mollusks of the Piacenzian correspond with the rise in sea level creating the Tamiami Subsea and Jackson Subsea of Florida, Duplin Subsea generally of South Carolina, and Yorktown Subsea of the Outer Banks and inland North Carolina. Dates have been established on the basis of the genera and species of mollusks found. Origin of the genus Homo The late Piacenzian may be when the genus Homo developed out of the ancestral genus Australopithecus. While the oldest known fossils unambiguously identified as Homo habilis date to just after the end of the Piacenzian (2.58 Ma), a fossilized jawbone that exhibits traits that are transitional between Australopithecus and Homo habilis was discovered in the Afar Triangle in 2015. The find was made by Ethiopian student Chalachew Seyoum at a site called Ledi-Geraru between the Mille and Awash rivers, in Afar Regional State (near ). Based on geological evidence from the Afar region, the individual would have lived just after a major climate shift, during which forests and waterways were rapidly replaced by arid savanna. Regarding the Afar region, and as stated in the journal Science: "Vertebrate fossils record a faunal turnover indicative of more open and probable arid habitats than those reconstructed earlier in this region, in broad agreement with hypotheses addressing the role of environmental forcing in hominin evolution at this time." This interpretation is consistent with hypotheses that emphasize the savanna as the ancestral environment that shaped the evolution of early Homo and other hominins. References Notes Literature External links Neogene timescale, at the website of the subcommission for stratigraphic information of the ICS Neogene timescale at the website of the Norwegian network of offshore records of geology and stratigraphy Piacenzian Microfossils: images of Piacenzian Foraminifera 02 Geological ages