Building better biochronology: New fossils and 40Ar/39Ar radioisotopic dates from Central Anatolia

Abstract

Türkiye's geographic position between Europe, Asia, and Africa gives it pivotal importance for understanding the local, interregional, and intercontinental dynamics of Neogene vertebrate evolution. Although rich in vertebrate fossil deposits spanning the Middle and Late Miocene, associated geochronology has been limited by the lack of available volcanic materials that allow radioisotopic dating and geochemical correlation. As a result, calibrating mammalian evolution has been largely restricted to the semicircular application of paleomagnetic inferences combined with temporally ill-constrained and geographically remote biochronological deductions. For example, fossils from three Greek localities and one Anatolian locality assigned to the primate genus Ouranopithecus lack datable samples, leaving its ages poorly constrained. Chronological calibration based on the ⁴⁰Ar/³⁹Ar results reported here demonstrates how a fauna-focused, precision geochronology can enhance a better understanding of evolving species lineages and the ecosystems they comprise.

Keywords: Miocene; Türkiye; biochronology; geochronology; paleontology.

Fig. 1.

Spatial and stratigraphic positions of fossils and ⁴⁰Ar/³⁹Ar dates. (A) Topographic map of Anatolia and Greece highlighting Miocene hominoid primate occurrences shown in blue (Ouranopithecus) and (other Miocene primate genera) in orange. The topographic map is made with GeoMapApp (www.geomapapp.org) under a CC BY license and topographic map color code is shown with the color-scale. The Central Anatolian Volcanic Province (CAVP), shown in the yellow box in the satellite imagery to the Right (Google Earth). Newly dated paleontological localities are marked by three-letter abbreviations in yellow. The cities of Kayseri and Nevşehir are marked in magenta. (B) Stratigraphic positions of the new ⁴⁰Ar/³⁹Ar dates calibrating the nearest fossil horizons in each study area. Additional details are provided in Fig. 2 and SI Appendix.

Fig. 2.

(A) Excavation of the vertebrate paleontology locality at YYA. Fossils were first encountered during road construction. (B) The stratigraphy visible in the roadcut, showing the positioning of the newly dated volcanic horizons and the bone bed just below. (C–E) Vertebrate fossils excavated in situ, showing the concentrated nature of the remains. (F) A panoramic view of the YYA large mammal fossils thus far recovered and cleaned. Bovids to the Left, horses in foreground, rhinos center, and proboscideans to the Right.