10-Million-Year-Old Fossils in Turkey Challenge What We Thought We Knew About Mammal Evolution

A groundbreaking study published in the Proceedings of the National Academy of Sciences has redefined the evolutionary timeline of mammals and possibly early human ancestors. Thanks to the precise application of argon-argon dating, a team led by Ferhat Kaya from the University of Oulu has pinpointed the ages of fossil-rich volcanic sediments in central Türkiye to between 7 and 10 million years old. The findings suggest that Anatolia may have played a far more central role in mammalian and primate evolution than previously assumed.

Volcanic Glass Turns Central Anatolia Into a Precise Evolutionary Clock

The fossil beds in central Anatolia, long known to researchers but poorly dated, have been tied to precise geological ages through advanced argon-argon dating. This method converts microscopic grains of volcanic glass into high-resolution time capsules, measuring isotope ratios that indicate when the volcanic material cooled and locked in argon gas. Unlike older comparative methods based on morphological similarities with fossils in other regions, which often came with error margins of two to three million years, Kaya’s team reduced this margin dramatically.

Their approach involved drilling directly through fossil-rich sediment layers to reach underlying pumice and lapilli—volcanic rocks formed from ancient eruptions. These materials contain feldspar crystals, which are ideal for isotope analysis. In many cases, bones lay within just two inches of the datable tuff, allowing extremely narrow age brackets. Kaya stated, “While radioisotopic methods are not new in determining the age of fossils, this represents a significant paradigm shift in dating volcanic sedimentary layers that contain mammal fossils.”

This new high-precision dataset gives researchers at least five reference points across the stratigraphy of the site, firmly anchoring over 2,600 fossil specimens to a highly reliable geochronological framework.

Anatolia’s Crossroads: Where Continents—And Species—Collided

The Central Anatolian Volcanic Province holds a uniquely strategic position between Africa, Asia, and Europe, serving as a corridor for animal migrations during Miocene climatic shifts. Every change in sea level or global temperature transformed the region into a convergence zone, where species from three continents met, mingled, and adapted. This makes it an unparalleled site to study faunal transitions over geological timescales.

Some of the most notable finds in this region include fossils of the large Miocene ape Ouranopithecus, long debated as a possible close relative—or even an early member—of the hominine lineage. The updated chronology places these apes in a bracket between 7.5 and 8.2 million years ago, a range that overlaps with the 8.7-million-year-old Anadoluvius skull found in Çankırı, just a few hundred kilometers away. This temporal overlap forces a reevaluation of assumptions about where and when hominines first emerged.

The revised dates suggest that eastern Mediterranean apes like Ouranopithecus and Anadoluvius could have coexisted with or even preceded early African hominines, challenging the long-held narrative that hominines exclusively evolved in sub-Saharan Africa.

Climate Shifts and Evolving Ecosystems Etched in Ash

Beyond evolutionary implications, the site paints a vivid picture of ecological change. Around 9.5 million years ago, the local environment was dominated by dense woodlands, favoring browsers such as ancient three-toed horses and early saber-toothed cats. But by 7.4 million years ago, the ecosystem had transformed into open grasslands, paralleling a global cooling trend recorded in deep-sea sediment cores.

The fossil record in Anatolia reflects this shift: herbivore communities transition from browsers to grazers, matching worldwide changes in vegetation and climate. The argon-argon dated horizons act as both biological censuses and climatic gauges, revealing how rising plateau elevations and falling temperatures forced mammalian species to adapt, migrate, or disappear.

Kaya’s study suggests that these volcanic ash layers provide “bulletproof ages” that link regional faunal transitions to global climate dynamics, a connection rarely so clearly established in paleontological data.

Rethinking the Origin Story of Early Humans

The implications for primate evolution are particularly provocative. The recalibrated ages for Ouranopithecus and Anadoluvius invite renewed debate over the geographic origins of the hominine clade, the group that includes modern humans, chimpanzees, and their extinct ancestors. A 2023 study had already proposed that eastern Mediterranean apes may represent the first radiation of hominines, predating African examples like Sahelanthropus.

If these apes evolved outside of Africa, it could suggest a southward migration of early hominines, reversing the traditionally accepted northward narrative. The updated dates provide the temporal resolution necessary to evaluate such claims rigorously. With further excavation and dating, the Anatolian fossil corridor may emerge as the epicenter of an alternative model for human origins.

A Blueprint for Rewriting Evolutionary History Worldwide

Kaya’s team believes this breakthrough is only the beginning. The methodology they applied in central Anatolia could be replicated in other volcanic regions where ash-filled gullies preserve fossil records. Locations such as the Andes, Java, or East African Rift—places where volcanic activity coincided with faunal evolution—could benefit from this high-resolution dating approach.

The team is now expanding its efforts, guided by remote sensing tools to locate more buried ash layers and fossiliferous strata across the Central Anatolian Volcanic Province. Every new volcanic glass shard offers another opportunity to pin down the stories of species migration, adaptation, and extinction with unprecedented precision.