Homo erectus paleoenvironments in the early Pleistocene Denizli Basin: an integrated paleontological, sedimentological and geochemical approach

The early Pleistocene travertines from the Denizli Basin (Turkey) that host the only one known Homo erectus from Anatolia (Kocabaş) are laterally interfingering with a succession of shallow, alkaline lake deposits. We studied the sedimentary succession, micro- and macropaleontology of the deposits and stable isotope compositions (δ¹⁸O and δ¹³C) of the mollusc shells in order to reconstruct paleoenvironments for these early hominins and explore the opportunities and limiting landscapes providing their life. Three units are defined in the upper part of the Quaternary succession which consists of a partially coeval succession of shallow lake carbonates, bedded fine-grained carbonates and travertines. The age of the studied fossiliferous travertine units is constrained by a variety of approaches between 1.2 and 1.6 Ma. The vertebrate fossils (Archidiskodon meridionalis, Palaeotragus, Metacervoceros, Cervalces, Stephanorhinus and two species of Equus) including Homo erectus derive from the uppermost travertines that formed at the shore of a shallow alkaline lake. The ostracods derived from the underlying lake deposits are abundant and well preserved. The assemblage consists of a mixture of brackish or strongly alkaline taxa (e.g. Cyprideis, Tyrrhenocythere, Loxoconcha and Amnicythere) together with fresh water ostracods (e.g. Candona, Pseudocandona, Eucypris, Lineocypris). The molluscs from the shore zone deposits experienced diagenetic alterations, probably caused by the travertine forming process, resulting in a unique recrystallization. Both ostracod and mollusc associations suggest the presence of an anomalohaline (or strongly alkaline) lake setting, constraining the habitat of the Homo erectus. The presence of travertine terraces next to the alkaline lake may have posed challenges on hominin occurrences, their habitat and landscape adaption.