Graecopithecus May Have Been Partially Bipedal, New Fossil Suggests

A 7.2 million-year-old femur discovered at the Azmaka fossil site in southern Bulgaria displays a mosaic of features suggesting a unique combination of locomotor abilities, including aspects of quadrupedalism and terrestrial bipedalism, according to a research team led by Professor Madelaine Böhme of the Senckenberg Center for Human Evolution and the Paleoenvironment at the University of Tübingen. Paleoanthropologists have tentatively attributed the fossil to Graecopithecusa species of fossil ape known from fragmentary remains in the Balkans and sometimes proposed as the earliest hominid.

Graecopithecus freybergi lived 7.2 million years ago in the dusty savannah of the Athens Basin. This view of Graecopithecus freybergiplace of discovery of Pyrgos Vassilissis, to the south-east on the plain of Athens and under a reddish cloud of dust from the Sahara; in the background: Mount Hymettos and Mount Lykabettos. Image credit: Velizar Simeonovski.

Graecopithecus is a controversial fossil ape from the Late Miocene, dated to approximately 7.2 million years ago.

Some researchers have proposed that it could be the first hominid – perhaps even older than the fossils traditionally linked to early hominids in Africa.

Until now, Graecopithecus was known from only two fossils: a partial lower jaw with teeth, discovered in 1944 near Athens, Greece; and an isolated upper premolar from Azmaka, Bulgaria, described in the 2010s.

“At 7.2 million years old, this ancestor, which we classify as belonging to the genus Graecopithecuscould be the oldest known human,” said Professor David Begun of the University of Toronto, co-author of the new study.

In the study, researchers examined a nearly complete femur (thigh bone) of Graecopithecus from the Azmaka website.

The new fossil was discovered in 2016 in floodplain deposits dating to around 7.2 million years ago.

The Azmaka bone has a spherical femoral head clearly clear of the neck and an elongated, obliquely ascending medial margin of the neck – a configuration characteristic of hominoids.

However, the specimen does not show the full set of specializations seen in later bipeds.

The neck-shaft angle is in the lower range of modern humans and approaches estimates from early hominids such as Orrorinbut below the higher angles typical of suspensory apes like orangutans.

According to the team, the combination of traits indicates a transitional form of bipedalism: neither a specialized suspensory climber, nor a fully engaged terrestrial biped.

Body mass estimates derived from femoral head and shaft dimensions suggest a Graecopithecus individual weighing approximately 23 to 24 kg, comparable to a small chimpanzee.

“A number of external and internal morphological features, such as the elongated and upward-pointing neck between the femur shaft and the head, the special attachment points for the gluteal muscles and the thickness of the outer bone layer, show similarities with bipedal fossil human ancestors and humans,” said Professor Nikolai Spassov, a researcher at the Bulgarian National Museum of Natural History.

“That’s where they differ from the thighs of arboreal monkeys.”

“However, Graecopithecus didn’t really move like modern humans do.

Azmaka’s environment, reconstructed as a bush and forest savannah near a braided river system, suggests that early terrestrial bipedalism may have emerged outside of dense forests.

The authors hypothesize that descendants of this population may have dispersed from Eurasia to Africa amid climatic and environmental changes that occurred in the eastern Mediterranean during the Late Miocene, potentially contributing to the ancestry of later African apes and hominids.

Whether the Azmaka femur will ultimately reshape the geographic narrative of human origins will depend on further discoveries.

But for now, it provides a rare glimpse into how and where upright walking first took hold – in a landscape of seasonal rivers and open forests, millions of years before the first widely accepted members of the human lineage appeared in Africa.

“Graecopithecus represents a stage in human evolution between our arboreal and terrestrial ancestors, such as the nearly 12 million year old species. Danuvius guggenmosi from the Hammerschmiede site in southern Germany and more recent discoveries in East Africa,” said Professor Begun.

“It could certainly be described as a missing link. Graecopithecus most likely descended from eight- to nine-million-year-old Balkan-Anatolian apes, such as Ouranopithecus And Anadoluviuswhich in turn evolved from Western and Central European ancestors.

“We know that large-scale climate changes in the eastern Mediterranean and western Asia led to the periodic emergence of vast semi-deserts and deserts eight to six million years ago. »

“This triggered several waves of dispersal of Eurasian mammals to Africa and laid the foundation for the current mammal fauna of African savannas,” concluded Professor Böhme.

The team’s results were published in November 2025 in the journal Paleobiodiversity and paleoenvironments.

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N. Spassov and others. An early form of terrestrial hominin bipedalism in the late Miocene of Bulgaria. Paleobio Paleoenvironmentpublished online November 13, 2025; doi: 10.1007/s12549-025-00691-0